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  • 1985-1989  (626)
  • 1925-1929
  • 1986  (626)
  • Biochemistry and Biotechnology  (519)
  • Life Sciences  (107)
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1310-1317 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two instruments were developed to mechanize the handling of anaerobic microorganisms for microbial mutant isolation. The instruments automatically dispense liquid or agar medium to large and small 96-well platesand petridishes. Protocols were developed for inoculating different microorganisms, and calibration curves of number of areas or wells inoculated versus cell concentration were prepared for bacteria, yeast and fungi (spores). Experiments with yeast auxotrophic mutants and fungal spores showed that microbe inoculation follows Poisson statistics in distributing a single microorganism per inoculation point. The isolation and identification of Yarrowia lipolytica auxotrophic, morphological, and temperature-sensitive or tolerant mutants demonstrated the use of the instruments for microbial screening.
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  • 102
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1289-1293 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Spherical beads of κ-carrageenan containing entrapped cells were prepared in a two-step process. First, the beads were formed by dispersing a warm carrageenan cell suspension into stirring oil. After cooling (gelation) the beads were cured by treatment with amines. Ten amines of various sizes and structures were tested. We evaluated the mechanical strength and the applicability of aminetreated gels as immobilization matrices. The results of critical compression tests indicate that linear and branched polyethylenimines (PEI) are both good curing agents. PEI treated carrageenan beads also exhibited superior resistance to heat and abrasion. Furthermore, PEI polymers were demonstrated to be effective in stabilizing the lactase activity of the free and immobilized Bacillus stearothermophilus cells. The immobilized cell preparations of Saccharomyces cerevisiae, B. stearothermophilus, and Flavobacterium sp. were treated with branched PEI and evaluated for the activity of invertase (EC 3.2.1.26), lactase (EC 3.2.1.23), and glucose isomerase (EC 5.3.1.18), respectively, in a packed bed reactor at 60°C. The apparent half-lives were 108, 39, and 64 days, respectively.
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  • 103
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1227-1232 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The thermophilic fungus Sporotrichum cellulophilum was immobilized with nonwoven materials for cellulase production. The cellulose powder concentration in the medium was an important factor controlling cellulase production. When the cellulose powder concentration in the nonwoven materials was more than 4%, cellulase production was suppressed. The growth of the immobilized fungi depended on the spaces in the nonwoven materials. Immobilized growing fungi were retained by the non-woven materials, and the supernatant medium did not contain mycelia. The heat stability of the immobilized growing fungus was higher than that of the free fungus. The immobilized fungus gave the same FPA as the free mycelium, but the lag time for cellulase production in the immobilized fungus was longer. It was necessary for the only medium to be changed in order to get the immobilized growing fungus to continue producing cellulase. In this instance there was no difference of lag time in comparison with the free cells, and the supply of cellulose powder and polypepton was reduced to two-thirds. After 23 exchanges of the medium (2.6 mg cellulose powder/1 cm3 nonwoven materials) FPA value was maintained. The periodic batch culture was continued for 69 days.
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  • 104
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1256-1260 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A one-dimensional model, taking into account the diffusion of substrate between the liquid phase and the solid support, has been used to describe fixed bed enzyme reactors. The equations were solved numerically, and the values of the different parameters were calculated by a nonlinear regression method. The model was applied to different systems. The results are presented and discussed.
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  • 105
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1261-1267 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using a well-mixed and temperature-led vessel, the diffusion characteristics of various solutes into spherical κ-carrageenan gel beads were experimentally investigated. The diffusion coefficient of glucose was markedly affected by the glucose concentration and the operating temperature. In all cases the diffusivity obtained was noticeably smaller than that of glucose in pure water. The experimental data also indicated an inverse relationship between the diffusivity and the polymer concentration used in the gel preparation. As well, the glucose diffusivity was affected by the presence of other solutes in the glucose solution. Electrolytes such as ammonium sulfate, KCl, and CaCl2 were observed to enhance the diffusion coefficient. On the other hand, the addition of arginine or bovine serum albumin had an adverse effect on the diffusivity. No diffusion of albumin into the gel beads was observed, and such a solute created a significant mass transfer resistance during the diffusion process.
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  • 106
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1268-1276 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biohydrogenation of C-18 unsaturated fatty acids was examined in a mixed culture of microorganisms prepared by inoculating a proper growth medium with a sample of rumen fluid. Some major factors influencing the hydrogenation capacity have been investigated. The age of the mixed culture, the type of inoculum used, the concentration of substrates as well as the presence of sterile rumen fluid in the growth medium were found to be important factors determining biohydrogenation behavior. It could be shown that the mixed microbial culture, which had been grown for about 24 h on a medium similar to that of Bryant and Robinson, contained sterile rumen fluid (10% v/v), and had been inoculated with a sample of the whole untreated rumen content, had the best biohydrogenation capacity. The culture was able to carry out the complete conversion of linoleic and linolenic acid to stearic acid.
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  • 107
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1462-1465 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of potassium ferrocyanide and EDTA on ethyl alcohol production from molasses by Saccharomyces cerevisiae were investigated on simulated batch pilotplant-scale conditions for alcoholic fermentation of molasses. Ethyl alcohol production was more sensitive to ferrocyanide than to EDTA. When ferrocyanide was introduced into the cultures at the time of inoculation, there was stimulation of ethyl alcohol production, with 261 ppm ferrocyanide producing the maximum effect, which was 3.0% more than in control cultures. When added during the propagation of the yeast, ferrocyanide depressed ethyl alcohol production by 4.0% maximum whereas EDTA stimulated ethyl alcohol production by 2.0%. Addition of ferrocyanide during the fermentation stage produced no significant effect on alcohol production, whereas over a wide range of EDTA concentration there was a steady increase in alcohol yield.
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  • 108
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1421-1431 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The optimal substrate feeding policy for the fed batch fermentation which is governed by product and substrate inhibited kinetics is presented. The conjunction point between nonsingular and singular arcs and the feeding policy along the singular arc are derived analytically in terms of the concentrations of substrate and product and the liquid volume. Thus, it is possible to determine the feeding rate by monitoring the state variables (i.e., closed loop control). As a specific example, an optimization study of the fed batch fermentation for ethanol production by Saccharomyces cerevisiae is presented. It is shown that the optimal feeding patterns are heavily dependent upon the initial conditions. The point selectivity provides the guideline for predicting the optimal feeding patterns and explaining the results of rigorous mathematical analysis.
    Additional Material: 15 Ill.
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  • 109
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1637-1646 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To calculate the transient accumulation of soluble organic matter in activated sludge, an equation based on COD and respirometry is described. In this approach the difference between the actual utilized organic matter and the metabolized matter is expressed as substrate transient accumulation. The amount of substrate generated by the lysis of dead microorganisms was taken into account, and the metabolized organic matter was expressed in two main endergonic functions of O2 consumption, that is, assimilation and maintenance. The equation thus derived was simplified to contain parameters such as COD and O2 consumption and tested on experimental results. The results show that the values obtained using this equation compared well to substrate removal in the absence of O2 in short-term batch cultures.
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  • 110
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1653-1656 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Culture filtrates from Trichoderma harzianum E58, T. reesei CL 847 and Penicillium sp. C 462 were assayed for β-glucosidase activity using a range of substrates and sugar analysis methods. Although sugar analyses by the dinitrosalicylic acid (DNS) and Nelson-Somogyi methods gave a similar profile, when increasing concentrations of salicin were assayed, considerably higher values were obtained with the DNS assay. The salicin concentration used for the assay greatly influenced the final β-glucosidase values with higher values obtained for T. harzianum E58 and T. reesei CL 847 at substrate concentrations of 1 mg/mL while optimum values for Penicillium sp. C 462 were obtained at substrate concentrations greater than 3 mg/mL. Low concentrations of salicin and p-nitro-phenyl-β-D-glucopyranoside (PNPG) gave the same response as cellobiose. Cellobiose should be used at concentrations greater than 3.74 mg/mL to avoid substrate limitation of the β-glucosidase assay.
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  • 111
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1657-1671 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics and mechanism of Fe(III) reduction to Fe(II) were studied in pure batch cultures of Pseudomonas sp. 200. The rate of iron reduction has been mechanistically related to aqueous phase iron speciation. In the absence of microbial activity the iron reduction rate was negligible. Initial rates of microbial iron reduction were accelerated more than 20-fold by the addition of equimolar quantities of nitrilotriacetic acid (NTA) to media initially containing 1.86 × 10-3M total Fe(III). Numerical techniques were utilized to quantify relationships between the observed rate of Fe(II) production and the calculated (equilibrium) aqueous phase speciation. These results indicate that soluble ferric iron species are not equivalent in terms of their susceptibility to bacterial (dissimilative) iron reduction. The concentration of Fe(NTA)(OH)22- correlated strongly with observed iron reduction rates. Ferrous iron species appeared to inhibit the reduction process.
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  • 112
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1690-1698 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Yeast nucleoproteins were chemically phosphorylated with phosphorus oxychloride (POCL3). Studies using 31P nuclear magnetic resonance (NMR) spectroscopy, stability to pH and lysine estimation all indicated that the ∊-amino group of lysine was the principal functional group phosphorylated. Phosphorylation of ca. 30% of the lysine residues resulted in removal of more than 85% of contaminant ribonucleic acid from protein precipitated at pH 4.2. Phosphorylation did not alter the amino acid composition of yeast proteins and was reversible under acidic conditions. Based on the data, a method for the preparation of phosphorylated yeast protein with low levels of nucleic acid is proposed.
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  • 113
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1672-1689 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A structured mathematical model for cellular metabolism in Escherichia coli has been extended to encompass the mechanistic structure surrounding the kinetics and control of transcription and translation. The dependence of transcription on RNA polymerase and the mechanism of translation initiation have been explicitly included. This model correctly simulates cell growth, cell composition, and the timing of chromosome synthesis as a function of extracellular substrate concentration for glucose-limited balanced growth. Simulation results for the subpopulation of RNA polymerase engaged in transcription and for the distribution of this subpopulation among different promoter sites agree closely with experimental findings, as do calculated estimates of the active ribosomal fraction. In addition, the existence of an antitermination system for transcription of stable RNA operons is supported by model results. This model should provide a useful framework for investigating metabolic perturbations to E. coli, such as those resulting from insertion of extra-chromosomal vectors into the cells.
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  • 114
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1769-1773 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A relatively simple and inexpensive anaerobic calorimeter was designed and evaluated by using a Hy-Cal Engineering BI-7 bidirectional heat-flux sensor to measure heat output from magnetically stirred I-L flask fermentations. The production of ethanol and cumulative heat output by Zymomonas mobilis were both linearly proportional to glucose concentrations up to 160 g/L.
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  • 115
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1761-1768 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of ethanol from starch by a coimmobilized mixed culture system of aerobic and anaerobic microorganisms in Ca-alginate gel beads was investigated. The mold Aspergillus awamori was used as an aerobic amylolytic microorganism and an anaerobic bacterium, Zymomonas mobilis, as an ethanol producer. By controlling the mixing ratio of the microorganisms in the inoculum size, a desirable coimmobilized mixed culture system, in which the aerobic mycelia grew on and near the oxygen-rich surface of the gel beads while the anaerobic bacterial cells mainly grew in the oxygen-deficient central part of the gel beads, was naturally established under the aerobic culture conditions, and ethanol could be directly produced from starch by the system. The ethanol productivity by the system in flask culture was particularly affected by the shear stress (dependent on the shaking speed) which controlled the mycelial growth on the surface of the gel beads. Under optimum culture conditions in the flask culture, the glucose produced was instantly consumed, and was not observed in the culture broth; the final concentration of ethanol produced from 100 g/L starch was 25 g/L and the yield coefficient for ethanol, Ypls, was 0.38. The ethanol productivity by the coimmobilized mixed culture system was compared with those by other various culture systems and the advantages of the system were clarified.
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  • 116
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1774-1779 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The irradiation with visible light of a photosensitizer dye like methylene blue was used to regenerate by electron transfer the oxidized form of a pyridine nucleotide coenzyme (NAD+). The process has been studied on a common enzymatic reaction: ethanol oxidation by alcohol-NAD+ oxidoreductase immobilized on polyacrylamide gel or porous glass balls. In the experimental conditions used, the initial NAD+ recycling rates were 2.33 × 104 cycles/h (polyacrylamide) and 3 × 104 cycles/h (glass balls). A total number of 49.5 × 104 cycles was obtained for 13 runs of 2 h. The enzyme immobilization strongly increased its stability: after 28 days at 20°C, the residual activity was 25% of the initial value.
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  • 117
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1801-1808 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A predictive model was developed to estimate the dewatering characteristics of waste-activated sludges. This model utilizes the COD-nitrogen ratio of the wastewater and the organic loading rate of the process to predict sludge filterability in terms of specific resistance. A completely mixed, continuous flow secondary treatment process with solids recycle was used for the cultivation of activated sludges. The sludge wasted from this process was used in Buchner funnel specific resistance determinations. The basic concepts involved in the development of the model were supported by sludge carbohydrate, protein, and surface charge data.
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  • 118
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1794-1800 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new immobilization technique suitable for coupled enzymes requiring cofactors was established. This is a droplet gel-entrapping method in which many small droplets including the enzymes are fixed in the gel. The first emulsion was prepared by mixing of a solution containing thermostable malate dehydrogenase (MDH) and formate dehydrogenase (FDH) with benzene containing a surfactant. The first emulsion was added to a solution containing polyethyleneglycol(#4000)diacrylate and N,N′-methylenebisacrylamide to prepare the second emulsion (w/o/w). After the second emulsion was gelled by addition of potassium persulfate and 3-dimethylaminopropionitrile, the benzene was removed. The expressed MDH and FDH activities of the MDH-FDH immobilized gel were 7.1 and 13.9% of the initial activities, respectively. The Km values of the gel were 0.60mM for formate and 1.5μM for NAD, respectively. The Km for formate and NAD were found to be extremely low. By using the column packed with 30 g gel having the MDH activity of 41.7 units and the FDH activity of 11.1 units, 13.8mM oxalacetate was completely converted to malate at 30°C. The malate production rate was not affected by the concentration of more than 50mM formate, more than 2mM oxalacetate, and more than 0.1 mM NAD, respectively. Long-term malate production was demonstrated at 30°C by passing the substrate solution containing the two substrates and NAD through the column. The maximum conversion ratio (7.8%) was obtained at the fifth day, and 83% of maximum productivity was maintained even after 3 weeks. The expressed FDH activity at the fifth day was calculated to be 20.5% of the initial activity.
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  • 119
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1832-1837 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extracellular β-xylosidase (1,4-β-D-xylan xylohydrolase, EC 3.2.1.37) from culture filtrates of Neurospora crassa was purified to homogeneity by preparative isoelectric focusing followed by gel electrophoresis. The molecular weight of the purified xylosidase was 83,000 D and the Km on p-nitrophenyl-β-D-xyloside was 0.047mM. The homogeneous xylanase (1,4-β-D-xylan xylanohydrolase, EC 3.2.1.8) and β-xylosidase showed differences in their mode of action towards xylooligosaccharides. The degree of hydrolysis of D-xylan by xylanase of N. crassa was 18%. Supplementation of β-xylosidase from the same organism resulted in 48% hydrolysis. The synergistic effect was more pronounced, with the hydrolysis of 68%, when a homogeneous preparation of β-xylosidase from Sclerotium rolfsii was added to the saccharification system.
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  • 120
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the plunging water jet system using inclined short nozzles, the flow characteristics such as the bubble penetration depth and the gas entrainment rate, which changed depending on the jet velocity, the nozzle diameter, the jet length, and the jet angle were first evaluated in an air-water system. A comparable investigation between our results and those of existing studies used the long nozzles on those characteristics revealed that both the bubble penetration depth and the gas entrainment rate differed depending on the nozzle length; that is, the nozzle-length-to-diameter ratio LN/DN and that of these characteristics the gas entrainment rate affected considerably by its magnitude and tended to be high when the nozzle of a large LN/DN ratio was used. It was also confirmed from the oxygen transfer experiments that the transfer efficiency at low jet velocities in the present water jet system was not inferior to the ones of other types of existing aeration systems; that is, the utilization of this jet aeration system to a high rate reactor for wastewater treatment or fermentation was sufficiently possible. The applicability of the plunging jet aeration method to microbial processes was then examined. As a typical example of microbial processes to be tested, the continuous treatment of an organic wastewater using activated sludge microorganisms was carried out, and the performance and related problem when this type of aeration system was applied to such a microbial process were investigated. Experimental results showed that, when viewed from the removal ability of dissolved organic matters, the plunging jet aeration system was capable of treating a wastewater of considerable high loading without the rate of oxygen transfer becoming the biooxydation-rate-limiting factor. Special attention was necessary for the choice of the liquid pump to be employed, however, due to the increased amount of fine suspended solids in the treated water caused by the shearing action between sludge flocks and pump blades.
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  • 121
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    Biotechnology and Bioengineering 28 (1986), S. 504-510 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The activities of cellulases and xylanase were determined in laboratory cultures of Aspergillus terreus F-413 performed on natural and chemically or hydrothermally pretreated oak sawdust. The best stimulation effects were obtained in the cultures containing sawdust treated with dioxane, sodium hydroxide, or phosphoric acid. Moreover, the sawdust pretreatment distinctly affected its enzymatic hydrolysis, especially when the preparation of hydrolase complex was isolated from the culture of A. terreus F-413 growing on the modified sawdust as a sole carbon source. The highest saccharification effect was observed when the sawdust was treated with dioxane, sodium hydroxide, or phosphoric acid. Glucose was the main product of sawdust decomposition found in the hydrolyzates.
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  • 122
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    Biotechnology and Bioengineering 28 (1986), S. 711-717 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alcoholic fermentations of starch hydrolysate by two different yeast strains, Saccharomyces cerevisiae(var. Vinal) and Saccharomyces oviformis(IMAP 383), have been studied in batch runs. In order to evaluate the different inhibition phenomena due to both substrate and product, a new kinetic equation is suggested.
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  • 123
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Both the forward and backward reactions of xylose isomerase (Sweetzyme Q) with xylose and glucose as substrates have been studied in terms of kinetics and thermodynamics. The relationship between the two reactions can thus be determined. Much attention has been given to the reaction with xylose as substrate. The optimal conditions of the xylose reaction in terms of pH, buffer, metal ions, substrate concentration, temperature, and ionic strength have been determined. These findings did not differ much from those reported for the glucose reaction. Equilibrium constants for the aldose to ketose conversion were more favorable in the case of glucose. The results obtained with continuous isomerization of xylose in columns packed with either Sweetzyme Q or Taka-Sweet were very similar to those obtained from batch isomerization processes. Particle size had a definite effect on reaction rate, which indicates that diffusion limitations do occur with the immobilized enzyme particles. Heat stability of Sweetzyme Q was good with t1/2 of 118, 248, and 1200 h at 70, 55, and 40°C, respectively. A novel method for the separation of xylose-xylulose mixtures with water as eluant on a specially prepared Dowex 1 × 8 column was developed. This technique has the capability of producing pure xylulose for industrial or research applications. A writ for a patent regarding this technique is at present prepared.
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  • 124
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    Biotechnology and Bioengineering 28 (1986), S. 718-727 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The development of granular sludge in thermophilic (55°C) upflow anaerobic sludge blanket reactors was investigated. Acetate and a mixture of acetate and butyrate were used as substrates, serving as models for acidified waste-waters. Granular sludge with either Methanothrix or Methanosarcina as the predominant acetate utilizing methanogen was cultivated by allowing the loading rate to increase whenever the acetate concentration in the effluent dropped below 200 and 700 mg COD/L, respectively. The highest methane generation rates, up to 162 kg CH4-COD/m3 day, or 2.53 mole CH4/L day, were achieved at hydraulic retention times down to 21 min, with granules consisting of Methanothrix. The formation of Methanothrix granules did not depend on the type of seed material, nor on the addition of inert support particles. The growth of granules proceeded rapidly with adapted seed material, even when the reactors were inoculated with low concentrations. With mesophilic seed materials growth of granules took much longer. Thermophilic Methanothrix granules strongly resemble mesophilic granules of the “filamentous” type. Some factors governing the thermophilic granulation process are discussed.
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  • 125
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    Biotechnology and Bioengineering 28 (1986), S. 728-735 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comparison of the relative performance of production techniques using coenzyme or cofactor electrochemical regeneration demonstrates the superiority of those processes in which the enzymatic reaction and the regeneration are conducted in the same reactor as opposed to those in which the reaction and regeneration are separated. For the former type of reactor, a method of calculation is proposed. This method is based on the solution of equations which describe the phenomena in modules representing three areas: the surface of the electrode, a layer where occur simultaneously the transport of material and the enzymatic reaction, and the bulk of the solution. This method is suggested for three types of reactor: those in which an enzyme solution is held close to an electrode by a semipermeable membrane, those in which an enzyme-charged membrane is in contact with an electrode, and those in which the enzyme is in solution in the vessel into which the electrode is dipped.
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  • 126
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    Biotechnology and Bioengineering 28 (1986), S. 741-746 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Tab.
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  • 127
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    Biotechnology and Bioengineering 28 (1986), S. 878-882 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A kinetic model that represents the reaction of hydrolysis of water-soluble cellulose derivatives by a mixed endo- and exoenzyme system is proposed with the following assumptions: at an early stage of the reaction, endoenzymes split the substrate molecule in order to supply the newly formed nonreducing ends to exoenzymes until the molecular weight of the substrates reaches a low value; after that point, the reaction kinetics obeys only the rate equation of the reaction of the exoenzymes in which the reaction parameters change linearly with decrease of the molecular weight of the substrates. Hydrolysis experiments of soluble cellulose derivatives, carboxymethyl cellulose and hydroxyethyl cellulose, were carried out with endo-and exoenzymes separated from Trichoderma Koningii cellulase. The critical molecular weight of the substrate, from that point the action of endoenzyme can be neglected, was determined from the experimental data. That was ca. 4000 D. With that value, the model fits well the experimental data. Synergism of both enzymes appears as enhancement of the rate of the reaction at the early stage of the reaction.
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  • 128
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    Biotechnology and Bioengineering 28 (1986), S. 1056-1063 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Isoelectric fractionation of the two major proteins of soy is characterized. Fractions are acid precipitated and cen-trifugally collected at pH 6.0 (glycinin) and pH 4.8 (β-conglycinin). Two extremes in the speed of acid addition (rapid, with no mixing, and slow, via acid dialysis, with complete mixing) are compared to determine their effects on the properties of the precipitate. Total protein yield, fraction composition, and aggregate microstructure do not depend significantly on the method of acid addition. Particle size distribution and hindered settling behavior do differ and are explained using a model of aggregate strength. The rapid acid addition produces larger primary particles, because of higher supersaturation, and yields larger aggregates, because of higher interparticle potential and stronger aggregates. Further aggregation in low-shear hindered settling is faster for the slowly precipitated aggregate because few of these bonding sites could survive the high-shear precipitator, whereas more can contribute to aggregation during hindered settling.
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  • 129
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    Biotechnology and Bioengineering 28 (1986), S. 1080-1085 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dehydrogenase activity assay of activated sludge using the redox dye 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride (INT) was investigated. INT-dehydrogenase activity (INT-DHA) was directly proportional to INT dosage and inversely proportional to bio-mass concentration over limited ranges. INT dosages exceeding 2.5m/M were toxic to dilute activated sludge suspensions. INT-DHA was greatest near pH 9, whereas the peak oxygen uptake rate (OUR) occurred at pH 8. Both INT-DHA and OUR varied inversely with sludge age, but INT-DHA was the more sensitive of the two parameters to this variable. Consistently good and highly significant correlations between INT-DHA and OUR of chlorine stressed activated sludge were found at sludge ages ranging 2.2-7.0 days.
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  • 130
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    Biotechnology and Bioengineering 28 (1986), S. 1086-1092 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentation media consist of a large number of chemicals which composition undergoes alteration during the course of fermentations. In consequence, the conventional methods and correlations for gas diffusion coefficient measurement and prediction cannot be easily applied to such systems. Oxygen diffusion coefficients have been measured in simulated chemical systems as well as in complex solutions of nutrient broth, using the polarographic technique introduced in a previous article. It is identified that sugars and salts are the major factors influencing oxygen diffusion coefficients in these aqueous fermentation media. The effect of salts on oxygen diffusion coefficients in electrolyte solutions has been found to be well correlated with the square root of total ionic strength of electrolyte solutions. The individual effect of glucose and its combined effect with salts are explored in order to reach rational correlations capable of predicting oxygen diffusion coefficients in synthetic fermentation media. For aqueous solutions of glucose plus salts, it is observed that the log-additive relationship can be used to account for the combined effect. Finally, a linear correlation has been established in measuring oxygen diffusion coefficients in aqueous solutions having different concentrations of nutrient broth.
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  • 131
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    Biotechnology and Bioengineering 28 (1986), S. 1119-1121 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 132
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    Biotechnology and Bioengineering 28 (1986), S. 1106-1118 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The successful operation of anaerobic digestion depends on the balanced growth of many bacterial species. The functions of the main groups of microorganisms present in a digester have been analyzed and a mathematical model constructed that describes the interactions among the microbial populations and their effect on the digester performance. The model was validated by comparing its predictions with actual digester operation. Several startup procedures were evaluated in the light of the model predictions and improvements on current operational practices suggested in order to minimize startup time.
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  • 133
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    Biotechnology and Bioengineering 28 (1986) 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 134
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    Biotechnology and Bioengineering 28 (1986), S. 1127-1137 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two microorganisms, E. coli and S. cerevisiae, competing for glucose were maintained in a stable cycle of coexistence by alternating the growth advantage between the two organisms by oscillating the pH in a Chemostat. Pure culture experiments found S. cerevisiae to be insensitive to pH between 5 and 4.3 with a maximum specific growth rate (μmax) of 0.4/hr; while μmax of E. coli decreased from 0.6 h-1 at pH 5 to 0.1 h-1 at pH 4.3. Steady-state and cross-inoculation chemostat runs at a dilution rate of 0.17 h-1 confirmed the expectation that the mixed culture system is unstable at constant pH with E. coli dominating at pH 5 and S. cerevisiae dominating at pH 4.3. Three pH oscillation experiments were performed at D =0.17 h-1 with 1 g per liter glucose feed. The 16 h/16 h cycle was stable for six periods with a stable alternating cycle of E. coli and S. cerevisiae being quickly established. A 18 h pH 5/14 h pH 4.3 cycle was found to be stable with smaller yeast concentrations. A 6 h/6 h cycle was found unstable with yeast washout. Simulation results were compared with these runs and were used to predict the onset of instability. Oscillations of pH can force stable persistence of a competing mixed culture that is otherwise unstable. Thus, varying conditions are experimentally demonstrated to be one explanation for competitive coexistence.
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  • 135
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    Biotechnology and Bioengineering 28 (1986), S. 1159-1165 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Very rapid or explosive drying of grains such as corn leads to obvious physical changes in the macrostructure of the grain kernel, probable alteration in starch molecular structure, and reduction in starch average molecular weight. These changes lead to greater susceptibility to attack by liquefying and saccharifying enzymes. Rates of formation of nonreducing and reducing sugars by liquefying and saccharifying enzymes applied to explosively dried and milled yellow dent corn and small-kernel flint corn were 3.3-10.6 times greater than rates for the normally milled grains. The enzymatic conversion of explosively dried flint corn containing absorbed ethyl alcohol, as would be the case if it had been used as an adsorbent to dewater aqueous ethyl alcohol, was not significantly different from that of ethyl-alcohol-free flint corn.
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  • 136
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    Biotechnology and Bioengineering 28 (1986), S. 1166-1171 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The adsorptive behavior of cells of Acetobacter aceti, ATCC 23746, on DEAE-, ECTEOLA-, TEAE-, and DEHPAE-cellulose ion exchangers in a modified Hoyer's medium at 30°C was investigated. The maximum observed adsorption capacities varied from 46 to 64 mg dry wt/g resin. The Langmuir isotherm form was used to fit the data, since the cells formed a monolayer on the resin and exhibited saturation. The equilibrium constant in the Langmuir expression was qualitatively correlated with the surface charge density of the resin. The adsorption was also “normalized” by considering the ionic capacities of the resins. The exceptionally high normalized adsorption capacity of ECTEOLA-cellulose, 261 mg dry wt/meq, may be explained by an interaction between the cell wall and the polyglyceryl chains of the exchanging groups in addition to the electrostatic effects. The effect of pH on the bacterial adsorption capacity of ECTEOLA-, TEAE-, and phosphate-cellulose resins was studied and the pl of the bacteria was estimated to be 3.0.
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  • 137
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    Biotechnology and Bioengineering 28 (1986), S. 1044-1055 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cybernetic models, developed earlier by the authors, have been evaluated experimentally for the growth of Klebsiella oxytoca in batch cultures using mixed substrates from glucose, xylose, arabinose, lactose, and fructose. Based entirely on information procured from batch growth on single substrates, the models accurately predict without further parameter fitting, diauxic growth on mixed substrates, automatically predicting the order in which the substrates are consumed. Even triauxic growth on a mixture of glucose, xylose, and lactose is predicted by the model based on single substrate data. Growth on glucose-fructose mixtures appears to need a slightly modified strategy for cybernetic variables.
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  • 138
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    Biotechnology and Bioengineering 28 (1986), S. 1093-1099 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A potentiometric penicillinase electrode is reported in which the base pH transducer is a thin-film anti-mony-antimony-oxide electrode deposited by vacuum evaporation. Several enzyme immobilization procedures have been examined and a crosslinked protein film found to be the most appropriate to this type of sensor. The use of an adjacent antimony-antimony-oxide track as a pseudoreference electrode was successfully demonstrated. The overall response was shown to be independent of the stirring rate above 100 rpm, but the kinetics of the response were found to depend markedly on the stirring rate. The intrinsic linear response range was 3 × 10-4Mto 7 × 10-3M penicillin G. Linearizing transforms that extend the useful range were examined.
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  • 139
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    Biotechnology and Bioengineering 28 (1986), S. 1100-1105 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Five endoglucanases (1,4-β-D-glucan-glucanohydrolase, EC 3.2.1.4) were isolated from Fusarium lini. Endo I and II were purified by preparative gel electrophoresis and Endo III, IV, and V were purified in a single-step procedure involving preparative flat-bed isoelectric focusing. All the endoglucanases were homogenous on disk gel electrophoresis and analytical isoelectric focusing in polyacrylamide gel. The pi values were between 6 and 6.6 for Endo III, IV, and V; for Endo I, the pi value was 8. The molecular weights of the enzymes were between 4 × 104 and 6.5 × 104. The Km values for endoglucanases using carboxymethyl cellulose (CM-cellulose) as the substrate were 2-12 mg/mL. The specificity of the enzymes was restricted to β-1, 4-linkages. All the enzymes showed activity towards D-xylan. The endoglucanases had high viscosity reducing activity with CM-cellulose. Striking synergism was observed for the hydrolysis of CM-cellulose by endoglucanases. Endo II, IV, and V attacked cellopentaose and cellotetraose more readily than cellotriose. Endo II and V hydrolyzed cellotriose, cellotetraose, and cellopentaose, yielding a mixture of cellobiose with a trace amount of glucose; endo IV produced only cellobiose.
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  • 140
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    Biotechnology and Bioengineering 28 (1986), S. 1122-1125 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sorghum was used as raw material for alcoholic fermentation without cooking. Two varieties of sorghum grown in Thailand, KU 439 and KU 257, contained 80.0 and 75.8% of total sugar. Optimum amount of sorghum for alcoholic fermentation should be between 30 and 35% (w/v) in the fermentation broth. In these conditions 13.0 and 12.6% (v/v) of alcohol could be obtained in 84 and 91.9% yield based on the theoretical value of the starch content from KU 439 and KU 257, respectively.
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  • 141
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    Biotechnology and Bioengineering 28 (1986), S. 1138-1153 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mixed culture anaerobic digestion model developed previously was applied to the evaluation of several digester control strategies. It was found that pH control by base addition or flow rate manipulation is inadequate. Based on an analysis of digester dynamics, a new control of the total suspended solids concentration at the feed was proposed through the manipulation of the underflow flow rate of the preceeding sedimentation unit. This control was tested in a variety of simulated runs and proved very effective in eliminating most of the usual causes of digester failure.
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  • 142
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    Biotechnology and Bioengineering 28 (1986), S. 1443-1445 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 143
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    Biotechnology and Bioengineering 28 (1986), S. 1449-1453 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 144
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    Biotechnology and Bioengineering 28 (1986), S. 1294-1301 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The productivity of a cell mass of Saccharomyces cerevisiae and enzymes of Eupenicillium javanicum increased by cultivation in anair-solid fluidized bed fermentor with agitators. The usefulness of the apparatus for the fluidized bed culture was verified. The productivity of amyiase and protease of the fungus by fluidized bed culture was twice as high as that by stationary culture, considering the dry weight of cells and the enzyme activity. Physiological properties of yeast cells were changed buy the fluidized bed culture; there was a decrease in the cell size of yeast and the changes to the aerobic properties of the yeast cells resulting from excessive supply of oxygen with a high flowrate of air.
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  • 145
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    Biotechnology and Bioengineering 28 (1986), S. 1302-1309 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The penetration of ultrasonic waves through opaque media and the large difference in the acoustic properties between air bubbles and the fermentation broth were used to measure the energy attenuation of pulsed ultrasound by the bubbles as the waves passed through the broth. This leads to an on-line determination of the specific interfacial area provided information is available about the holdup or bubble mean diameter. This article gives the principle of the method and demonstrates how the measured interfacial area may be used in evaluating the mass transfer coefficient of a fermentation system in a bubble column.
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  • 146
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    Biotechnology and Bioengineering 28 (1986), S. 1408-1420 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Based upon the general characteristics of the optimal feed rate profiles presented in an earlier article, efficient computational algorithms have been developed for fed-batch fermentation processes described by four or less mass balance equations. These algorithms make computations of optimal substrate feed rate profiles straight forward and simple for various fed-batch cultures for such products as antibiotics, amino acids, enzymes, alcohols, and cell mass. Numerical examples of penicillin fermentation and bacterial cell mass production are given in detail, illustrating the use of these algorithms.
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  • 147
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    Biotechnology and Bioengineering 28 (1986), S. 1876-1878 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cellulase produced by fungus Trichoderma viride was immobilized on agarose beads (Sepharose 4B) activated by cyanogen bromide and also on activated agarose beads that contained spacer arm (activated CH-Sepharose 4B and Affi-Gel 15). The CMCase activity retained by immobilized cellulase on activated Sepharose containing the spacer tended to be higher than that immobilized without spacer, although the extent of protein immobilization was lower. Also, the higher substrate specificity for cellulase immobilized on beads with spacer was obtained for cellobiose, acid-swollen cellulose, or cellulose powder. The hydrolysis product from their substrates was mainly glucose.
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  • 148
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    Biotechnology and Bioengineering 28 (1986), S. 1879-1883 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 149
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    Biotechnology and Bioengineering 28 (1986) 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 150
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Permeabilities of several solutes through the composite membranes containing phospholipids have been measured. They were inversely proportional to the content of the phospholipids in the membrane. Both the permeability of solutes and the degree of permeability change around the phase transition temperature of the phospholipids for the hydrophobic solutes such as n-butanol and salicylamide were larger than those for the hydrophilic solutes such as amino acids and pyridoxine. These results suggest thatthe permeation path of hydrophobic solutes is different from that of hydrophilic ones. The addition of phosphatidyl ethanolamine, phosphatidyl serine, or phosphatidic acid to the composite membrane influenced the solute permeability due to the introduced negative charge and/or the change in the molecular packing of phospholipid.
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  • 151
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    Biotechnology and Bioengineering 28 (1986), S. 21-28 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biosorption of uranium and lead by lyophilized cells of Streptomyces longwoodensis was examined as a function of metal concentration, pH, cell concentration, and culture age. Cells harvested from the stationary growth phase exhibited an exceptionally high capacity for uranium (0.44 g U/g dry weight) at pH 5. Calculated values of the distribution coefficient and separation factor indicated a strong preference of the cell mass for uranyl ions over lead ions. The specific uranium uptake was similar for the cell wall and the cytoplasmic fraction. Uranium uptake was associated with an increase in hydrogen ion concentration, and phosphorus analysis of whole cells indicated a simple stoichiometric ratio between uranium uptake and phosphorus content. It is proposed that metal ions are bound to phosphodiester residues present both in the cell wall and cytoplasmic fractions. Based on this model, it was shown that uranium accumulation exhibits a maximum at pH 4.6 that is supported by experimental data from previous investigations.
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  • 152
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    Biotechnology and Bioengineering 28 (1986), S. 29-40 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A separate role for water activity in the conversion of sugars to ethanol by two strains of yeast is identified. During fermentation of both single and mixed sugar substrates, the water activity was shown to remain constant during the logarithmic growth phase. This is despite the changes in concentration of substrates and product, the constancy reflecting the fact that the greater influence of ethanol on the solution activity is counterbalanced, in the early stages of the fermentation, by its low yield. The end of the log phase of growth coincides with the start of a period of gradually decreasing water activity. For the more ethanol-tolerant strain UQM66Y, growth was found to cease at a constant value of water activity while that for the less tolerant strain UQM70Y depended on both ethanol concentration and water activity. It is argued that water activity is a more appropriate variable than ethanol concentration for describing some of the nonspecific inhibitory effects apparent in ethanol fermentations. A straightforward method for the calculation of water activity during such fermentations based on the use of solution osmolality is presented.
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  • 153
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Poly(maleic anhydride styrene) graft copolymers of cellulose, pectin polygalacturonic acid salt, calcium polygalacturonate, and starch were prepared and used to immobilize proteins. The cellulose grafts coupled quite appreciable quantities of acid phosphatase, glucose oxidase, and trypsin. However, the general retention of activity was somewhat disappointing. Further investigation with acid phosphatase showed that the amount of enzyme immobilized increased as the amount of anhydride in the graft copolymer increased but no such relationship existed for the enzymic activity. The cellulose graft copolymers were hydrolyzed and it appeared that the carboxyl group aided adsorption of the enzyme. Attempts to couple acid phosphatase using CMC through the free carboxyl groups, created by hydrolysis, gave only a small increase in the extent of protein coupling. However, the unhydrolyzed system gave a useful degree of immobilization of cells of Bacillus stearothermophilus, as did a poly(maleic anhydride/styrene)-cocellulose system. Attempts to improve the activity by using grafts based on other polysaccharide supports met with mixed success. Pectin products were soluble. Polygalacturonic acid products were partially soluble and extremely high levels of enzymic activity were obtained. This was probably due in part to the hydrophilic nature of the system, which also encouraged absorption of the enzyme. Attempts were made to reduce the solubility by using the calcium pectinate salt. Immobilization of acid phosphatase and trypsin resulted in inceased protein coupling but relatively poor activities were attained. A starch based system gave similar results. Calcium polygalacturonate was used to prepare an insoluble graft copolymeric system containing acrylonitrile-comaleic anhydride. The resulting gels gave excellent coupling with acid phosphatase which had a very good retention of activity.
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  • 154
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    Biotechnology and Bioengineering 28 (1986), S. 64-72 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Urokinase was immobilized by entrapment to fibrocollagenous tubes in order to develop a small-caliber fibrinolytic vascular prosthesis. Several parameters associated with the immobilization process were studied in order to optimize bound urokinase activity and stability. A total of 37% of the absorbing enzyme was attached to the collagen tube and 38% of the attached enzyme retained esterolytic activity, under optimal conditions. In the crosslink step of the entrapment process, the glutaraldehyde concentration was varied from 0.01 to 5.00% (i.e., 0.01, 0.1, 1.0, 3.0, and 5.0%). Urokinase activity was optimized at a 1.0% glutaraldehyde crosslink concentration. Urokinase-bound fibrocollagenous tubes (UK-FCT) prepared at the above glutaraldehyde concentrations were tested for their activity with time. The UK-FCT's with 0.1, 1.0, and 3.0% glutaraldehyde retained constant activity for at least 75 h operation time. The UK-FCT's with 0.1, 1.0, and 3.0% glutaraldehyde retained constant activity for at least 75 h operation time. The UK-FCT's with 5.0 and 0.01% glutaraldehyde remained stable for the first 50 h operation time, but begandeactivating beyond 50 h. UK-FCT'S Crosslinked with 0.01, 0.1, 1.0, and 5.0% glutaraldehyde were recrosslinked with 0.02% glutaraldehyde for 24 h, after they have been operating for 50 h, and the effect of reexposing the crosslink agent on the stability of the UK-FCT's was studied. The results showed that 0.02% glutaraldehyde reexposure had no effect on 0.1, 1.0, and 5.0% glutaraldehyde crosslinked UK-FCT's but exerted an inhibitory effect on a 0.01% crosslink density UK-FCT. Several fibrocollagenous tubes were exposed to various glutaraldehyde concentrations prior to immobilizing urokinase. The subsequent immobilization process occurred under optimal conditions. The effect of the precrosslink step on the activity of the UK-FCT was studied. Results indicated that UK-FCT activity decreases as the precrosslink density increases. The UK-FCT's made under optimal conditions remained stable for at least 75 h operation time, corresponding to ca.1 year of storage time. Ex vivo exposure of UK-FCT's to whole canine blood did not affect catalytic activity. Implantation of a UK-FCT by carotid arterial interposition via an end-to-end anastomosis and subsequent excision after 60 days resulted in an enhanced esterolytic activity which decreased with time to a level close to preoperative levels.
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  • 155
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    Biotechnology and Bioengineering 28 (1986), S. 97-100 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
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  • 156
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    Biotechnology and Bioengineering 28 (1986), S. 101-106 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 157
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    Biotechnology and Bioengineering 28 (1986), S. 112-114 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article provides the analysis on biomass yields and energetic yields of the oleaginous yeasts. The biomass yields of the oleaginous yeasts are consistently lower than nonoleaginous microorganisms, whereas their energetic yields are higher. Data inconsistencies of literature are explained by the variation of energy contents of oleaginous yeasts.
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  • 158
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    Biotechnology and Bioengineering 28 (1986), S. 122-125 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 159
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    Biotechnology and Bioengineering 28 (1986), S. 126-128 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 160
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    Biotechnology and Bioengineering 28 (1986), S. 133-137 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
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  • 161
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    Biotechnology and Bioengineering 28 (1986), S. 142-145 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 162
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Transient responses of continuously growing yeast cultures to step changes in dilution rate were influenced by (1) the preshift conditions of the culture, (2) the magnitude of the dilution rate increase, (3) the organism involved, and (4) the type of bioreactor used. The sensitivity of transient responses to seemingly minor differences in the design of experiments indicated that this type of investigation may be a means to analyze kinetics of microbial cultures as well as the effectiveness of bioreactors.
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  • 163
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    Biotechnology and Bioengineering 28 (1986), S. 160-166 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics in batch culture of the acetone butanol fermentation by Clostridium acetobutylicum is compared on glucose, xylose, and mixtures of both sugars. The fastest initial growth and transition from an acid to a solvent metabolism occurs on glucose, with a final 62 g/L glucose conversion. On xylose, an initial slower growth rate and a longer metabolic transition result in higher cellular and acids concentration, thus in a level of fermented sugar limited to 47 g/L. Batch fermentations on mixtures of glucose and xylose show that both sugars can be fermented, with a higher rate for glucose. However, xylose fermentation is inducible and inhibited at glucose level above 15 g/L. Mixtures of glucose and xylose yield the highest amount of fermented sugars, up to 68 g/L, as a result of both a fast metabolic transition on glucose and a strong acid reconsumption on xylose. In all cases, solvent production is triggered at a total acid concentration between 4 and 5 g/L, whereas the final inhibition of the fermentation takes place at a total butanol and acid concentration between 18 and 20 g/L.
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  • 164
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    Biotechnology and Bioengineering 28 (1986) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 165
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    Biotechnology and Bioengineering 28 (1986), S. 151-159 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The present work deals with maltodextrin hydrolysis by glucoamylase immobilized onto corn stover in a fluidized bed reactor. An industrial enzyme preparation was covalently grafted onto corn stover, yielding an activity of up to 372 U/g and 1700 U/g for support particle sizes of 0.8 and 0.2 mm, respectively. A detailed kinetic study, using a differential reactor, allowed the characterization of the influence of mass transfer resistance on the reaction catalyzed by immobilized glucoamylase. A simple and general mathematical model was then developed to describe the experimental conversion data and found to be valid.
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  • 166
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    Biotechnology and Bioengineering 28 (1986), S. 167-175 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics in fed-batch cultures of acetone butanol fermentation by Clostridium acetobutylicum is compared on glucose, xylose, and mixtures of both sugars. The final conversion yield of sugars into solvents always increases with the sugar feeding rate. At low feeding rates, the sugar concentration in the medium becomes limiting, which results in a slower cellular growth, a slower metabolic transition from an acid to a solvent fermentation and, thus, a higher accumulation of acids. It is only at sufficiently high feeding rates that fed-batch fermentations yield kinetic results comparable to those of batch fermentations. With mixtures of glucose and xylose, because of a maintained low glucose level, both sugars are taken up at the same rate during a first fermentation period. An earlier accumulation of xylose when the fermentation becomes inhibited suggest that xylose utilization is inhibited when the catabolic flux of glucose alone can satisfy the metabolic activity of the cell. Kinetic results with batch and fed-batch fermentations indicate several important features of the regulation of C. acetobutylicum metabolism: an early inhibition by the produced acids; an initiation of solvent formation between 4 and 6 g/L acetic and butyric acid depending on the metabolic activity of the cell; a metabolic transition from acids to solvents production at a rate closely related to the rate of sugar uptake; during solvent production, a reassimilation of acids above a minimal rate of sugar consumption of 0.2 h-1; a final inhibition of the fermentation at a total butanol and acids concentration of ca. 20 g/L.
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  • 167
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    Biotechnology and Bioengineering 28 (1986), S. 185-190 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Method of flow cytometric analysis have recently been developed that make it possible to obtain segregated data on a single cell basis. In particular, it has been previously demonstrated that protein distributions obtained by flow cytometry give information about the law of growth of the cell population and the law of growth of the single cell; thus these distribution show how the microbial population is actually growing at the moment of the analysis and may yield more accurate and predictive information. We have extended the analysis of protein distribution and cell volume distribution to continuous cultures of Saccharomyces cerevisiae growing in a glucose-limited chemostat. We have found that: (1) to each dilution rate corresponds a given protein and volume distribution that does not change with time in steady state cultures; (2) there is a good proportionality between the average cell volume and the average protein content; (3) the protein distribution obtained can be easily analyzed with the model of growth of yeast previously developed in our laboratory; (4) the analysis of perturbed states shows that both protein distribution and volume distribution change very quickly; thus they are very sensitive parameters and can be used for monitoring and controlling industrial fermentation.
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  • 168
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    Biotechnology and Bioengineering 28 (1986), S. 233-239 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article describes a method for the chemical immobilization of concanavalin A (Con A) on the inside wall of a single hollow cellulose fiber for use in glucose affinity sensor. Periodate oxidation of cellulose fiber followed by a spacer for Con A attachment was deemed to be the most optimal procedure for achieving the highest sensitivity of the sensor without compromising its physical integrity. The effects of variables like the duration of periodate oxidation and its concentration and pH of the spacer coupling step and its duration have been examined. The mechanical strength of the hollow fiber as well as its permeability to the analyte (glucose) have been evaluated prior to and after Con A coupling process.It has been demonstrated that Con A bound hollow fiber prepared according to the procedure outlined here can be successfully used to construct glucose affinity sensor for operation in the physiological range of glucose concentrations.
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  • 169
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    Biotechnology and Bioengineering 28 (1986), S. 240-246 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The concepts of phase separation, anaerobic activated sludge process, and alkali pretreatment have been incorporated in this investigation with the objective of developing rational and cost-effective designs of diphasic anaerobic activated sludge systems, with and without alkali treatment, for methane recovery from water hyacinth (WH). Evaluation of process kinetics and optimization analyses of laboratory data reveal that a diphasic system with alkali treatment could be designed with an alkali pretreatment step (3.6% Na2CO3 + 2.5% Ca(OH)2 (w/w) of WH, 24 h duration) followed by an open acid phase (2.1 days HRT) and closed methane reactor with sludge recycle (5.7 days HRT, 7.7 days MCRT) for gas yield of 50 L/kg WH/d at 35-37°C. Likewise, a diphasic system without alkali treatment could be designed with an open acid phase (2 days HRT) followed by closed methane reactor with sludge recycle (3.2 days HRT, 6 days MCRT) for gas yield of 32.5 L/kg WH/d at 35-37°C. Detailed economic analyses bring forth greater cost-efficacy of the diphasic system without alkali treatment and reveal that the advantage accrued in terms of higher gas yield is overshadowed by the cost of chemicals in the diphasic system with alkali treatment.
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  • 170
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    Biotechnology and Bioengineering 28 (1986), S. 283-287 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
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  • 171
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    Biotechnology and Bioengineering 28 (1986), S. 288-293 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wheat straw has been hydrolized with sulfuric acid at 34 and 90°C. The treatment at 90°C yields complete solubilization of hemicellulose to xylose and arabinose without significant amounts of furfural. The influence of acid concentration was studied and the kinetics of the acid-catalyzed hydrolysis has been modeled suggesting a two-consecutive reactions mechanism. This model is useful to explain the different behavior of the concentration of the two main sugars produced. The enhanced cellulose accessibility to enzymatic attack is also reported.
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  • 172
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    Biotechnology and Bioengineering 28 (1986), S. 269-282 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Within the framework of a program aiming to improve the existing extractive recovery technology of fermentation products, the state of the art is critically reviewed. The acids under consideration are propionic, lactic, pyruvic, succinic, fumaric, maleic, malic, itaconic, tartaric, citric, and isocitric, all obtained by the aerobic fermentation of glucose via the glycolytic pathway and glyoxylate bypass. With no exception, it is the undissociated monomeric acid that is extracted into carbon-bonded and phosphorus-bonded oxygen donor extractants. In the organic phase, the acids are usually dimerized. The extractive transfer process obeys the Nernst law, and the measured partition coefficients range from about 0.003 for aliphatic hydrocarbons to about 2 to 3 for aliphatic alcohols and ketones to about 10 or more for organophosphates. Equally high distribution ratios are measured when long-chain tertiary amines are employed as extractants, forming bulky salts preferentially soluble in the organic phase.
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  • 173
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    Biotechnology and Bioengineering 28 (1986) 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 174
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    Biotechnology and Bioengineering 28 (1986), S. 247-255 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model for the batch culture of Clostridium acetobutylicum was formulated using experimental data for anaerobic solvent production. The model summarizes biochemical as well as physiological aspects of growth and metabolite synthesis by the production strain. The key fermentation rates are expressed and evaluated with regard to substrate consumption and butanol end-product inhibitory effects. Parametric sensitivity analysis of the batch process model was carried out, indicating the importance of the key process parameters.
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  • 175
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    Biotechnology and Bioengineering 28 (1986), S. 314-328 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using a continuum approach and observing conservation principles, an analytical mathematical model of microbial interaction in biofilms was developed. The model predicts changes in biofilm thickness and describes the dynamics and spatial distribution of microbial species and substrates in the film. It allows for biomass detachment due to shear stress and sloughing, external mass transfer limitations, as well as variations in substrate concentrations in the bulk liquid. A computer implementation of the model is provided using an example of heterotrophicautotrophic competition to illustrate how the observed phenomena can be numerically reproduced and indicating how they might affect overall biofilm performance.
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  • 176
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    Biotechnology and Bioengineering 28 (1986), S. 356-361 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
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  • 177
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    Biotechnology and Bioengineering 28 (1986), S. 362-371 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An adaptive measuring system of the main variables of biotechnical processes based on the theory of estimation is elaborated upon here. All stages of system synthesis are considered. It is shown that for an adaptive measuring system all a priori information on modelling and measurement noise and process mathematical models must be used. The data of direct and indirect measurements are used for estimating the main variables. The performance of the proposed measuring system was checked using imitative modelling.
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  • 178
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    Biotechnology and Bioengineering 28 (1986), S. 387-393 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of precipitation of soya protein has been examined in a tubular flow reactor with the precipitants, ammonium sulfate, ethanol, divalent calcium, and sulfuric acid. The precipitate growth profiles obtained in all cases showed the rapid formation of a precipitate phase and the attainment of a final size within 16 s. The final mean particle diameter dm varied with precipitating agent used in the order: sulfuric acid (12.5 μm) 〉 ethanol (7.5 μm) ≈ calcium ion (7.2 μm) 〉 ammonium sulfate (3.1 μm). In the case of ethanol precipitation, changes in the design of the contacting section of the reactor led to differences in the precipitate growth curve. Protein solubility curves are also presented, and with the reactor data, they provide a convenient method for assessing the effect of precipitating agent on the design of protein precipitation reactors.
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  • 179
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    Biotechnology and Bioengineering 28 (1986), S. 394-404 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biodegradation of lignin by fungi was studied in shake flasks using 14C-labeled kraft lignin and in a deep-tank fermentor using unlabeled kraft lignin. Among the fungi screened, A. fumigatus - isolated in our laboratories - was most potent in lignin biotransformation. Dialysis-type fermentation, designed to study possible accumulation of low MW lignin-derived products, showed no such accumulation. Recalcitrant carbohydrates like mi-crocrystalline cellulose supported higher lignolytic activity than easily metabolized carbohydrates like cellobiose. An assay developed to distinguish between CO2 evolved from lignin and carbohydrate substrates demonstrated no stoichiometric correlation between the metabolism of the two cosubstrates. The submerged fermentations with unlabeled lignin are difficult to monitor since chemical assays do not give accurate and true results. Lignolytic efficiencies that allowed monitoring of such fermentations were defined. Degraded lignins were analyzed for structural modifications. A. fumigatus was clearly superior to C. versicolor in all aspects of lignin degradation; A. fumigatus brought about substantial demethoxylation and dehydroxylation, whereas C. versicolor degraded lignins closely resembled undegraded kraft lignin. There was a good agreement among the different indices of lignin degradation, namely, 14CO evolution, OCH3 loss, OH loss, and monomer and dimer yield after permanganate oxidation.
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  • 180
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    Biotechnology and Bioengineering 28 (1986), S. 405-416 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mold growth and differentiation are closely related to the formation of secondary products. In solid-substrate fermentations this interrelationship is often more completely realized than in submerged cultures. Solid substrate reactions are used commercially in a limited manner in the western world, but are relatively common in Asia. Basic studies in solid-substrate fermentation should yield results applicable to all types of commercial mold fermentations for the production of a secondary product. This paper presents a relatively simple model for the growth of a mold colony on a solid surface with a defined medium utilizing glucose. Unlike submerged cultures the model must account for both cellular differentiation and the spatial heterogeneity in the system. Model parameters were estimated independently using literature values. The results of the simulation studies suggest that mass transfer limitations are at least partially responsible for the proliferation of differentiated structures on solid substrates as compared to liquid cultures. Since the concentration profile depends on the depth of the substratum, conditions that enhance conidia production can be achieved by controlling the depth of the solid medium.
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  • 181
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    Biotechnology and Bioengineering 28 (1986), S. 549-553 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Xylose transport, xylose reductase, and xylitol dehydrogenase activities are demonstrated in Saccharomyces cerevisiae. The enzymes in the xylose catabolic pathway necessary for the conversion of xylose to xylulose are present, although S. cerevisiae cannot grow on xylose as a sole carbon source. Xylose transport is less efficient than glucose transport, and its rate is dependent upon aeration. Xylose reductase appears to be a xylose inducible enzyme and xylitol dehydrogenase activity is constitutive, although both are repressed by glucose. Both xylose reductase and xylitol dehydrogenase activities are five- to tenfold lower in S. cerevisiae as compared to Candida utilis. In vivo conversion of 14C-xylose in S. cerevisiae is demonstrated and xylitol is detected, although no significant levels of any other 14C-labeled metabolites (e. g., ethanol) are observed.
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  • 182
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    Biotechnology and Bioengineering 28 (1986), S. 564-569 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Steam-exploded aspen has been examined as a candidate feedstock for both cellulose production and enzymatic hydrolysis of wood. Batch and fed-batch cultivation methods were evaluated and compared with previous experiments using ball-milled, crystalline cellulose (Solka Floe). Batch cultivation of Trichoderma reesei Rut C-30 on 9 wt% water-washed aspen yielded enzyme productivities and activities comparable to those obtained on Solka Floe (40 FP IU/L-h; 7. 5 FP IU/mL). Fed-batch cultivation of Rut C-30 resulted in higher enzyme productivities and tilers than batch cultivation (50 FP IU/L-h; 15 FP IU/mL). However, the overall enzyme production performance was lower than on Solka Floe at comparable cellulose feeding rates and concentrations. This may be due to the accumulation of steam explosion by-products and lignin in the fermentor.The hydroiysis of water-washed steam-exploded aspen was performed at different enzyme loadings and wood concentrations. Glucose production, using 10 and 15wt% suspension, showed that while glucose concentration increased with wood load, the yield of glucose derived from cellulose decreased. With 10wt% suspensions, it was possible to obtain a cellous conversion to glucose above 95%. Low cellulose levels in the hydrolyzates indicated that the filter paper activity ratios (approximately 1.5), a significant result since the fungus was grown exclusively on wood. mIt also suggested that the observed yield decrease is more likely to be caused by glucose than cellobiose inhibition of the enzymes.
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  • 183
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    Biotechnology and Bioengineering 28 (1986), S. 578-584 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Coalescence frequency has been measured in an air-sparged bubble column by observing the rate with which insoluble tracer gases were mixed within the dispersed gas phase. The effects of gas-sparge rate and salt concentration were examined. Coalescence frequencies increased with increasing gas-sparge rates approximately in proportion to the increase in gas-phase hold up. The coalescence frequency decreased with NaCI concentration to a minimum frequency about half the frequency observed in pure water. Bubble size distributions were also measured in the air-sparged column. The size distribution changed significantly over the same range of NaCI concentration as variations in the coalescence frequency were observed. The gas-sparge rate showed no effect on the bubble size.
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  • 184
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    Biotechnology and Bioengineering 28 (1986), S. 570-577 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model for the cell separation technique of centrifugal elutriation is developed. The model simulates both steady and non-steady-state operation of the elutriator. The model can be used to predict the required set of flow rates of elutriating liquid necessary to fractionate a cell culture, the required time of sampling before steady state is achieved, and the range of cell size/cell density combinations contained in any fraction. The model predictions were verified experimentally. Variations in cell density and cell size due to the suspending environment have a significant effect on the accuracy (although not the trends) of the model predictions. Quantification of these variations will lead to significantly more accurate model predictions. An enhanced separation method was developed using the model, to yield finer separation of a cell culture than previously possible. The use of the centrifugal elutriator may now be given a firm theoretical basis, with the quality of separation understood in terms of the basic theory of operation.
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  • 185
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    Biotechnology and Bioengineering 28 (1986), S. 605-608 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 186
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    Biotechnology and Bioengineering 28 (1986), S. 747-750 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 187
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    Biotechnology and Bioengineering 28 (1986), S. 751-755 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
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  • 188
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    Biotechnology and Bioengineering 28 (1986) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 189
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The problem of dilute solvent concentration in butanol-acetone fermentations can be solved by using reverse osmosis to dewater the fermentation liquor. Polyamide membranes have a potential application in a butanol-acetone fermentation and exhibited rejection rates as high as 98%. Optimum rejection of butanol in the fermentation liquor occurred at recoveries of 20-45%. Flux ranged from 0.05 to 0.6 L m-2 min-1.
    Additional Material: 11 Ill.
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  • 190
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments were carried out to identify an efficient procedure for decreasing the amount of excess sludge in deep aeration columns. Incubation characteristics, especially cellular yield, are closely related to excess sludge, maximum specific growth rate, and chemical oxygen demand. They were measured here for the bacterium Pseudomonas aeruginosa, which tends to be predominant in sewage treatment, at a pressure remaining constant or periodically changing in the range of 1-6 atm (abs.). Cellular yields tended to decrease over 1-2 min pressure cycles; in steady operation they decreased considerably with increasing pressure or dissolved oxygen concentration. Maximum specific growth rates were moderately affected by periodic changes in pressure or dissolved oxygen concentration but markedly affected in the higher concentration range under steady operation. Substrate consumption rates on the other hand, were little affected in either case. The values of chemical oxygen demand ranged from 220 to 250 mg/L, and were thus nearly constant.
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  • 191
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    Biotechnology and Bioengineering 28 (1986), S. 646-658 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growth of a hybridoma culture, along with production of monoclonal antibody, was demonstrated over extended periods in polysulfone hollow fiber membrane modules. The molecular weight cutoffs of the membranes were 70,000, 50,000, and 100,000 daltons. The hybridoma cell line, designated 65/26, produced IgG (2b/κ) directed at mouse thymus cell surface antigen, TL.1. Cell growth occurred in the shell space of the reactor, using supplemented RPMI 1640 (20% fetal bovine serum) supplied from a separate reservoir vessel through the hollow fiber lumen. The reservoir contained 125 mL media, which was changed every 4 days. Concentrations of immunoglobulin were determined by an enzyme immunoassay (using protein A and alkaline phosphatase-labeled antibody conjugate). For the 10K, 50K, and 100K hollow fiber membrane modules, the maximum IgG concentrations detected in the 2.5-mL shell space were 47.5-80, 510, and 740 μg/mL, respectively. In the 125-mL reservoir for the 100K hollow fiber membrane module, the IgG concentration was measured at 260 μg/mL These values compare with an IgG concentration of 1 μg/mL when grown in a standard tissue culture flask and 3.2-7.6 μg/mL when grown in 100 ml media in a spinner flask. In addition, 10K and 50K hollow fiber membrane modules were run in a mode that decreased the fetal bovine serum supplement with time. Differences between these systems suggest that it is possible to obtain high IgG accumulation rates, both during and after the exponential growth phase of the hybridoma population.
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  • 192
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    Biotechnology and Bioengineering 28 (1986), S. 678-683 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Batch and continuous fermentations with Clostridium thermoaceticum (ATCC 39073) using automatic pH control were conducted. The value of μmax obtained from batch fermentation was about 0.14 h-1; acetate yield, which was both growth and non-growth associated, was about 2 mole of acetic acid/mole of glucose, compared with a theoretical maximum value of 3. This low yield, compared with literature data, may be explained by glucose loss through a combination of degradation routes. Continuous fermentation could be sustained for 1600 h or more without contamination problems. Continuous fermentation at high dilution rates indicates that μmax may be well above 0.17 h-1 when fresh feed medium is used. Acetate yields in continuous fermentation were about 77% of theoretical or 2.3 mole of acetic acid/mole of glucose.
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  • 193
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    Biotechnology and Bioengineering 28 (1986), S. 700-710 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous cultures of Saccharomyces cerevisiae are known to exhibit oscillatory behavior in the oxidative region. Important findings of a series of experiments conducted to identify the causes for initiation of and the means for elimination of oscillations in these cultures are reported in this paper. These oscillations are seen to be connected to the growth kinetics of the microorganism and are induced at very low glucose concentrations and at dissolved oxygen (DO) levels that are neither high nor low (DO values between 20 and 78% air saturation at a dilution rate of 0.2 h-1 and pH of 5.5 at 30°C). The oscillatory behavior is encountered over a range of dilution rates (0.09-0.25 h-1 at 30°C for pH = 5.5 and DO = 50% air saturation). The oscillations can be eliminated by raising the DO level above a critical value or by lowering the DO level below a critical value.
    Additional Material: 9 Ill.
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  • 194
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel mechanistic model for the growth of baker's yeast on glucoseis presented. It is based on the fact that glucose degradation proceeds via two pathways under conditions of aerobic ethanol formation. Part is metabolized oxidatively and part reductively, with ethanol being the end product of reductive energy metabolism. The corresponding metabolic state is designated oxidoreductive. Ethanol can be used oxidatively only. Maximum rates of oxidative glucose and ethanol degradation are governed by the respiratory capacity of the cells. The model is formulated by using the stoichiometric growth equations for pure oxidative and reductive (fermentative) glucose and ethanol metabolism. Together with the experimentally determinable yield coefficients (YX/S) for the respective metabolic pathways, the resulting equation system is sufficiently determined. The superiority of the presented model over hitherto published ones is based on two essential novelities. (1) The model was developed on experimentally easily accessible parameters only. (2) For the modeling of aerobic ethanol formation, the substrate flow was split into two simultaneously operating (i.e., in parallel) metabolic pathways that exhibit different but constant energy-generating efficiencies (respiration and fermentation) and consequently different and constant biomass yields (YX/S). The model allows the prediction of experimental data without parameter adaption in a biologically dubious manner.
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  • 195
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    Biotechnology and Bioengineering 28 (1986), S. 952-959 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Many of the sophisticated sensors desirable for monitoring bioreactors cannot be placed in the bioreactor either because they are not steam sterilizable or because they require nonphysiological operating conditions. Such sensors can be used if they are separated from the bioreactor. Separation of the sensor from the bioreactor causes a time lag in data acquisition. This results in several complexities in the development of an appropriate and stable feedback control system based on a separated sensor. This paper analyzes the optimal control of a bioreactor with a separated sensor without a time lag and analyzes the feedback control (but not necessarily the optimal control) with a time lag. Simulation results indicate that this type of analysis could be extended to more general bioreactor operating conditions.
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  • 196
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    Biotechnology and Bioengineering 28 (1986), S. 972-976 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The data on ethanol-water vapor-liquid equilibrium in the presence of cellulase enzyme, nutrients, yeast, and rice straw indicated a substantial increase in ethanol concentration in vapor phase at reduced pressures. Maximum relative volatility of ethanol in the presence of added components is approximately twice that of a pure ethanol-water system. The equation correlating the activity coefficient and ethanol concentration in the liquid phase adequately represents the equilibrium behavior.
    Additional Material: 8 Ill.
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  • 197
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    Biotechnology and Bioengineering 28 (1986), S. 977-987 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A series-type enzyme deactivation model is used to model and to quantitate some more complex enzyme deacti-vations. The influence of temperature, pH, immobilization, chemical modifier (inhibitor or protector), substrate, and metal ion on the inactivation kinetics and on the parameter values is examined. In some cases the influence of two parameters on enzyme inactivations is presented. This provides further physical insights into enzyme inactivation and stabilization processes.
    Additional Material: 12 Ill.
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  • 198
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    Biotechnology and Bioengineering 28 (1986), S. 965-971 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of the presence of more easily degradable alternative carbon sources on the biodegradation of toxic waste components is of great practical importance. In this work, a mixed phenol/glucose waste was fed to two heterogeneous populations acclimated to different conditions: one was acclimated to phenol as a sole source of carbon and one to a mixed phenol/glucose substrate. Batch substrate utilization experiments were performed under both growth and nonproliferating (no medium nitrogen source) conditions in order to assess substrate removal patterns at the levels of enzyme production and enzyme function. The results indicated that the substrate removal pattern exhibited by the cells was significantly influenced by the acclimation characteristics of the culture. The phenol acclimated cells showed an initial preference for phenol, but the presence of glucose hindered phenol removal rate under both growth and nonproliferating conditions. The cells acclimated to the mixed phenol/glucose waste demonstrated rapid initial glucose removal with a slower concomitant utilization of phenol; acclimation to the mixed waste evidently had a significant impact on the substrate removal pattern for this mixed substrate system.
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  • 199
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    Biotechnology and Bioengineering 28 (1986), S. 1007-1013 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The time course of the peroxidative bromination of propylene accompanied by in situ generation of hydrogen peroxide by glucose oxidase was examined to improve the productivity of propylene bromohydrin. To prevent the rapid inactivation of lactoperoxidase by excess hydrogen peroxide, it was effective to use lactoperoxidase in large excess as compared with glucose oxidase, and to raise the concentration of bromide ion. However, the rate of glucose consumption was lowered at high concentrations of bromide ion, and at higher mole fraction of oxygen as compared with propylene in the gas mixture. Therefore, it seemed that for the favorable production of bromohydrin there existed the optimal conditions for the concentration of bromide ion and for the composition of oxygen-propylene gas mixture. Such kinetic behaviors of the sequential enzymatic reactions were explained by a mechanism involving free hypobromous acid as a reactive intermediate. Furthermore, the stability of the coimmobilized enzymes with k-carrageenan gels was investigated in continuous operations. The half-life of the enzymes was ca. 60 h for the production of propylene bromohydrin.
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  • 200
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    Biotechnology and Bioengineering 28 (1986), S. 1154-1158 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetic properties of collagen-bound firefly luciferase have been investigated. Under definite hydrodynamic conditions with low agitation in the reaction medium, the observed behavior is modified compared to the enzyme free in solution: reducing the stirring rate decreases the observed enzymatic activity. But diffusional resistances alone cannot account for these atypical kinetics though mass transfer may certainly play an important role during the transient state of the bioluminescent reaction. After immobilization, the time necessary to reach the steady state increased from 300 ms to 3 min and the two substrates, luciferin and ATP, behave differently with respect to the enzyme: The nature of the saturating substrate first in contact with the bound enzyme is not indifferent suggesting that immobilization can reveal behaviors or mechanisms which are not visualized with the free enzyme.
    Additional Material: 4 Ill.
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