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  • 1980-1984  (6,345)
  • 1960-1964  (4,962)
  • General Chemistry  (9,373)
  • Biochemistry and Biotechnology  (1,933)
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Year
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 788-796 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A washed carrot substrate, prepared with high yields and easy handling properties, was found to be a suitable substrate for studying cellulolytic and pectinolytic degradation processes. A cellulase from Trichoderma reesei, and Rohament P, a macerating enzyme from Aspergillus alleaceǔs in endopolygalacturonase, degraded the washed carrot substrate to an extent of 60%. With the combined action of both enzymes, degradation was more than 80%. Simultaneous action of both enzymes was more efficient than their sequential use. The effect of temperature, pH, incubation time, enzyme concentration, and substrate concentration on the degradation by the single enzymes and their mixture were studied. Gas chromatographic sugar analysis revealed that Rohament P liberated glucose, arabinose, and galactose in the low-molecular-weight fraction obtained by ultrafiltration, in addition to high amounts of galacturonic acid. These carbohydrates were also found in the high-molecular-weight fraction (retentate) together with rhamnose and mannose. Cellulase BC released mainly glucose, although galacturonic acid, arabinose, xylose, and mannose were also detected both in the ultrafiltrate and retentate. Morphologically, during Rohament P degradation of the washed carrot substrate, damaged tissues and disintegrated cells were seen, whereas on cellulase BC action mainly disintegrated cell walls were observed.
    Additional Material: 9 Ill.
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  • 102
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 807-810 
    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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  • 103
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 820-823 
    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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  • 104
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 827-827 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 105
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 828-835 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Upjohn Company uses filtration to remove microorganisms and particulates from air and other gases which may come in contact with sterile products. To validate the microbial retentivity of these filters, they were challenged with an aerosol of Bacillus subtilis var niger spores. An aerosol challenge was used because it more closely simulated the use for which these filters were designed. The test apparatus was constructed of autoclavable components using a jet-type nebulizer and heated air mixing tube. Characterization of the aerosol particle size distribution with a particle size analyzer demonstrated that 80% of the particles had a diameter of × 3.0 times;m and that the particles had a mean mass diameter of 1.9 times;m with a geometric standard deviation of 1.8 times;m. Studies conducted with aerosols of Bacillus subtilis var niger spores demonstrated that the test apparatus could recover ca. 50% of the spores that were aerosolized. Hydrophobic filters from various manufactures were challenged with an aerosol of at least 108 spores of Bacillus subtilis. All filters tested could retain at least 109 spores when physical integrity of the filter was verfield.
    Additional Material: 8 Ill.
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  • 106
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1409-1417 
    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 cellular reproduction and the rate and extent of synthesis of extracellular polymeric substances (EPS) were investigated for P. aeruginosa growing in glucose-limited chemostats. μmax and Ks estimates of 0.4 h-1 and 2 mg glucose C/L, respectively, at 25°C were obtained for this bacterium. The extent of EPS formation was inversely related to the growth rate of P. aeruginosa. The rate of EPS formation had both growth- and non-growth-associated components. The growth-associated polymer formation rate coefficient (k) was 0.3 mg polymer C/mg cellular C and the non-growth-associated polymer formation rate coefficient (k′) was 0.04 mg polymer C/mg cellular C/h. The values for k and k′ must be regarded as provisional since the product formation data were quite variable at low dilution rates. Estimates of the cellular (Yx/s) and polymer (Yp/s) yield coefficients were 0.3 mg cellular C/mg glucose C and 0.6 mg polymer C/mg glucose C, respectively. Most of the non-growth-associated consumption of glucose detected was due to exopolymer formation.
    Additional Material: 7 Ill.
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  • 107
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1445-1448 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fluidized bed biofilm reactor using sand as the carrier particle was employed to study the effects of superficial velocity on the removal of nitrates as well as on the growth of the biofilm. Velocity was found to affect significantly both nitrate removal and biofilm growth. An analysis based on heterogenous catalysis was used to describe the denitrification process. There is good agreement between analysis and experimental measurements for startup and steady-state operating conditions.
    Additional Material: 5 Ill.
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  • 108
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 936-941 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two empirical models for the enzymatic hydrolysis of cellulose are used to analyze the same set of experimental data to determine if one model is superior to the other. Both models adequately describe the data. The parameters in both models may be correlated to the hydrolysis conditions of enzyme, substrate, and product inhibitor concentrations. Both empirical models have features which are consistent with theoretical models of cellulose hydrolysis.
    Additional Material: 9 Ill.
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  • 109
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 970-972 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To convert sugar mixtures containing cellobiose, glucose, and xylose to ethanol in a single step, the possibility of using a coculture consisting of Clostridium saccharolyticum and Zymomonas anaerobia was studied. In monoculture, C. saccharolyticum utilized all three sugars; however, it preferentially utilized glucose and produced acetic acid in addition to ethanol. The formation of acetic acid from the metabolism of glucose inhibited the growth of C. saccharolyticum and, consequently, the utilization of cellobiose and xylose. In monoculture, Z. anaerobia utilized glucose at a rate of 50 g/L day, but it did not ferment cellobiose or xylose. In coculture, Z. anaerobia converted most of the glucose to ethanol during the lag phase of growth of C. saccharolyticum, which then converted cellobiose and xylose to ethanol. The use of this coculture increased both the rate and the efficiency of the conversion of these three sugars to ethanol, and produced relatively small amounts of acetic acid.
    Additional Material: 2 Ill.
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  • 110
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 998-1002 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Horse liver alcohol dehydrogenase, which catalyzes oxidoreductions for a broad spectrum of substrates of organic chemical interest, was immobilized on CNBr-activated Sepharose and on decylamine-substituted agarose. The specific activities of the immobilized enzyme preparations were compared with the free enzyme, and the apparent Km values of the preparations were determined for a selection of substrates. At pH 9 and 60°C, soluble liver alcohol dehydrogenase was rapidly inactivated, while the enzyme immobilized on CNBr-activated Sepharose was more stable. Adenosine monophosphate (AMP), adenosine diphosphate, and adenosine diphosphoribose protected the free and immobilized alcohol dehydrogenase against heat inactivation. On storage under a variety of conditions, AMP effectively stabilized free horse liver alcohol dehydrogenase and the immobilized preparations.
    Additional Material: 4 Ill.
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  • 111
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 112
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1042-1053 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the wake of an earlier advanced multicomponent-multispecies biological treatment model, the authors suggest algorithms to substantially decrease the number of free coefficients. Operation of a number of experiments with the multicomponent-multispecies model has helped to further our understanding of the mechanism of biological treatment.
    Additional Material: 8 Ill.
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  • 113
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Individual monosaccharides present in bagasse hemicellulose were determined using HPLC and other chromatographic procedures. The presence of higher oligomers of the monosaccharides could also be determined. No single procedure can separate and identify all the naturally occurring monosaccharides. The pentosan fraction of bagasse wa successfully hydrolyzed and extracted with 5% (m/v)HCl, and the rate of release of individual monosaccharides was determined. Xylose was the main component in the hydrolyzates, while glucose, arabinose, and galactose present in the side chains of the pentosans were initially released at a fast rate. This treatment resulted in obtaining 229 mg/g xylose (85% of theoretical maximum) and 44 mg/g glucose from bagasse. Only arabinose (2.8 mg/g) and galactose (0.75 mg/g) was also present in detectable quantities. A total of 309 mg monosaccharides were obtained from 1 g of bagasse by this treatment. The results indicated that hydrolysis conditions for specific plant materials depend on the composition of the specific material being utilized. A part of the pentosan fraction (77.1%) was hydrolyzed at a high rate, while 22.9% was more stable and hydrolyzed more slowly. Although 39.8% dry bagasse could be obtained in solution by treatment with dilute alkali, only about 72% of the available hemicelluloses could be extracted in this way if the bagasse was not delignified beforehand. Amino acids and peptides or proteins were also extracted to very much the same with the alkali.
    Additional Material: 6 Ill.
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  • 114
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1098-1107 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fuel ethanol (95%) was produced from fodder beets in two farm-scale processes. In the first process, involving conventional submerged fermentation of the fodder beets in a mash, ethanol and a feed (PF) rich in protein, fat, and fiber were produced. Ethanol yields of 70 L/metric ton (7 gal/ton) were obtained; however, resulting beers had low ethanol concentrations [3-5% (v/v)]. The high viscosity of medium and low sugar, beet mashes caused mixing problems which prevented any further increase of beet sugar in the mash. The severely limited the maximum attainable ethanol concentration during fermentation, thereby making the beer costly to distill into fuel ethanol and the process energy inefficient. In order to achieve distillably worthwhile ethanol concentrations of 8-10% (v/v), we developed and tested a solid-phase fermentation process (continuous). In preliminary trials, this system produced fermented pulp with over 8% (v/v) ethanol corresponding to an ethanol yield of 87 L/metric ton (21 gal/ton). Production costs with this novel process are $0.47/L ($1.77/gal) and the energy balance is 2.11. These preliminary cost estimates indicate that fodder beets are potentially competitive with corn as an ethanol feedstock. Additional research, however, is warranted to more precisely refine individual costs, energy balances and the actual value of the PF.
    Additional Material: 4 Ill.
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  • 115
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1126-1127 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: NO Abstract.
    Additional Material: 1 Ill.
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  • 116
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1139-1139 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 117
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1140-1140 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 118
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1141-1145 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An inducible β-galactosidase from an extremely thermophilic organism, Thermus strain 4-1A, has been isolated and partially purified. There were significant dissimilarities to T. aquaticus β-galactosidase. It had a pl of 4.5, was inhibited by sulphydryl inhibitors and a number of transition metals, and was activated by EDTA and SH-containing reagents. The β-galactosidase showed strong product inhibition, and weaker inhibition by some other mono- and disaccharides. It was very stable up to 90°C at pH 8. On immobilization by diazonium linkage to porous glass, the pH optimum (6.0), the KM with ONPG (5mM) and the product inhibition were not altered.
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  • 119
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design and operation of an industrial penicillin-V deacylation reactor is simulated, using a kinetic expression and mass transport parameters for the immobilized enzyme particles which were determined experimentally in a previous study. It is desirable to use a series of equalsized plug flow reactors with pH control at the entrance to each reactor, and with a possibility of recycling reactant in each reactor. These measures are necessary to avoid a steep pH profile through the reactor; the deacylation reaction is accompanied by an increase of acidity of the reaction medium, and H+ is a strong inhibitor and may deactivate the enzyme. The optimization study which is carried out at a fixed penicillin conversion of x = 0.99 shows that it is uneconomical to use penicillin feed concentrations above 150mM-175mM, and that the buffer concentration in the reaction medium should not be less than 50mM-75mM. Increasing the number of reactors from 4 to 8 or 10 leads to higher productivity of 6-APA, and a moderate recycle in the first couple of reactors diminishes the sharp decrease in pH which will be found in a straight plug flow reactor operation of the equipment. Higher pumping costs and lower productivity are unavoidable drawbacks of an operation mode where the separation costs for the product mixture are desired to be low.
    Additional Material: 6 Ill.
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  • 120
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1508-1510 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 121
    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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  • 122
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1430-1435 
    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 presents a clear experimental determination of the behavior of nutrient uptake rate, mean cell nutrient content, and specific growth rate following the injection of pulses of additional limiting nutrient into a chemostat culture of Chlamydomonas reinhardii. The uptake rate per cell is a hyperbolic function of external nutrient concentration. The specific growth rate is related to the mean cell nutrient content by a hysteresis loop. The data obtained is used to test the performance of the Caperon-Droop mean cell quota model. It is demonstrated that this model cannot be used under severe transient conditions, even when modified by the introduction of a discrete time delay, a simple memory function, or time-dependent intracellular nutrient processing.
    Additional Material: 8 Ill.
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  • 123
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1475-1484 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Enzymatic corn starch liquefaction with α-amylase was carried out. Molecular weight distributions of the resulting hydrolysates are presented using aqueous size exclusion chromatographic techniques. It is demonstrated that despite the fact that the enzyme employed reacts in a random endoacting manner, the product distributions are nonrandom. The results are explained in part by a multimerization process whereby the polymeric substrate molecules preferentially associate, forming intermolecular aggregates. These aggregates are either a consequence of the manner in which the material is deposited into the native granular structure of starch or due to intrinsic physical chemical properties of the polysaccharide. In the latter case, the results are shown to correspond to known multimerized amylose, although complete characterization of the polysaccharide is currently not available. The results presented are used to develop a simplified kinetic model of starch liquefaction and shown to simulate the product distributions accurately.
    Additional Material: 11 Ill.
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  • 124
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1492-1497 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The quantitative effects of carbohydrate levels, degree of initial saccharification, glucoamylase dosage, temperature, and fermentation time were investigated using a Box-Wilson central composite design protocol. With Saccharomyces cerevisiae ATCC 4126, it was found that the use of a partially saccharified starch substrate markedly increased yields and attainable alcohol levels. Balancing the degree of initial saccharification with the level of glucoamylase used to complete hydrolysis was found necessary to obtain optimum yields. The temperature optimum was found to be 36°C. The regression equations obtained were used to model the fermentation in order to determine optimum fermentation conditions.
    Additional Material: 7 Ill.
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  • 125
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1498-1505 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Removal of hemicellulose by acid pretreatment in a flow reactor followed by enzymatic hydrolysis of the neutralized slurry has resulted in glucose yields as high as 95% for mixed hardwood. For white pine, however, the maximum glucose yield is 65%. Although pine has a higher extractives content, removal of the extractives prior to enzymatic hydrolysis does not increases the glucose yield. Pore size measurements reveal that the increase in pore volume, in the size range of the cellulase molecule, following pretreatment for pine is only about one-half the value obtained with mixed hardwood. This suggests that pore volume is an important determinant of substrate-enzyme reactivity.
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  • 126
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 670-676 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of alcohol/water/catalyst mixtures to delignify wood allows the lignin to be recovered in a usable form while leaving the carbohydrate fraction relatively intact. The effects of temperature, reaction time, and the type of solvent and catalyst on the delignification of milled poplar wood were investigated. The lignin, cellulose, and hemicellulose composition of the pretreated material was measured for each treatment condition. In addition, the pretreated samples were subjected to enzymatic hydrolysis using the cellulases produced by the thermophilic bacterium Thermomonospora sp. YX. The extent of enzymatic hydrolysis was characterized using an empirical model, and the results were used to examine the effectiveness of the pretreatment.
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  • 127
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 682-686 
    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 derives a number of equations which can be used in both continuous and the semicontinuous cultures of microorganism populations in chemostat systems. Using these equations, some phenomena which have been known for many years can be explained reasonably in terms of chemical kinetics, and a number of analytical solutions can be obtained instead of numerical solutions previously published.
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  • 128
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 691-698 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical description of a low-frequency, dual-source acoustic treatment of protein precipitates is presented. Two mechanisms for the potential improvement of the centrifugal separation of precipitates are proposed. They are acoustic aggregation, which causes an increase in particle size, and aggregate deformation, which results in an increase in aggregate density. Experiments with isoelectric soya protein precipitate indicated that the extent of ageing prior to acoustic conditioning is important. Support for both aggregation and dewatering was found and a maximum increases in the particle settling velocity of 20% was observed.
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  • 129
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    Biotechnology and Bioengineering 26 (1984), S. 702-713 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study was performed to evaluate the effects of the air sparge rate, working liquid volume, liquid feed rate onto the disk, and disk diameter on the foam-breaking performance of foam-breaking apparatus with a rotating disk (FARD) installed in the bubble column. Experimental results showed that the smaller the air sparge rate and working liquid volume were, and the larger the liquid feed rate and disk diameter, the lower the critical disk rotational speed required for reduced foam-breaking. The presence of the effective ranges of the disk diameter and liquid feed rate for foam breaking was also confirmed. Furthermore, the quantitative predictions of the upper limits of the liquid feed rate, foam-breaking regions, and the required foam-breaking power were carried out, based on the results obtained above. Comparison of the FARD with two conventional mechanical foam-breaking spray-type apparati also demonstrated the highest level of the FARD in respect not only to foam-breaking performance but also to power requirements.
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  • 130
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 742-747 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mutant of Saccharomyces cerevisiae, which forms large, multicellular flocs in liquid culture, rapidly fermented media containing high concentrations of glucose (100-180 g/L) in a continuous nonaerated tower fermentor at 30°C. The fermentor operated continuously for seven months. Batch and tower fermentor data were fitted to a kinetic model incorporating linear ethanol inhibition and Monod dependence on glucose. Conversion, ethanol yield, and ethanol productivity were related to the apparent fermentation time for initial glucose concentrations of 130 and 180 g/L. Productivities of 8-12 g ethanol/L h were achieved through the yeast bed giving conversions exceeding 90% of the theoretical yield.
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  • 131
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    Biotechnology and Bioengineering 26 (1984), S. 452-456 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Purified human α1 proteinase inhibitor, a plasma glycoprotein with a molecular weight of 5.3 × 104 daltons and a major serine protease inhibitor has been covalently coupled to dextrans with molecular weights of 1.77 × 104 and 1.03 × 104 daltons. The coupled conjugates were soluble in aqueous medium and stable up to 6 months at +5°C. Increased moles of dextran/mole protein ratio during coupling resulted in progressive decreases of inhibitory capacity, immunogenicity, and the association constant (kassoc) between the enzyme and the inhibitor. Compared to the native protein, the soluble conjugates showed improved stability at pH 3.0 and heat stability at 60°C. At 60°C, no loss of inhibitory capacity has been seen up to 60 min for the conjugates during which time the native protein lost greater than 90% of its inhibitory capacity. The presence of antioxidant catalase was needed to prevent oxidative degradation by hydrogen peroxide.
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  • 132
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    Biotechnology and Bioengineering 26 (1984), S. 477-480 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Effluent from the caustic extraction stage of a bleach plant is highly colored due to the presence of dissolved products from lignin chlorination and oxidation. Color removal from the effluent by hydrogen peroxide at neutral pH was catalyzed by addition of horseradish peroxidase. The catalysis with peroxidase (20 mg/L) was observed over a wide range of peroxide concentrations (0.1mM-500mM), but the largest effect was between 1mM and 100mM. The pH optimum for catalysis was around 5.0, while the basal rate of noncatalyzed peroxide color removal simply increased with pH within the range tested (3-10). Peroxidase catalysis at pH 7.6 reached a maximum at 40°C in 4 h assays with 10mM peroxide, and disappeared above 60°C. Compared with mycelial color removal by Coriolus versicolor, the rate of color removal by peroxide plus peroxidase was initially faster (first 4 h), but the extent of color removal after 48 h was higher with the fungal treatment. Further addition of peroxidase to the enzyme-treated effluent did not produce additional catalysis. Thus, the peroxide/peroxidase system did not fully represent the metabolic route used by the fungus.
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  • 133
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The massive conversion of δ-aminolevulinic acid (ALA) to protochlorophyllide (Pchlide) and the massive conversion of chlorophyllide a (Chlide a) to chlorophyll a (Chl a) are two essential conditions for the ALA-dependent assembly of photosynthetic membranes in vitro. In this work, we describe the development of a cell-free system capable of the forementioned biosynthetic activities at rates higher than in vivo, for the first 2 h of dark-incubation. The cell-free system consisted of (1) etiochloroplasts prepared from kinetin and gibberellic-acid-pretreated cucumber cotyledons, and (2) cofactors and additives described elsewhere and which are needed for the massive conversion of ALA to Pchlide, (3) high concentrations of ATP, MgCl2, and an isoprenol alcohol such as phytol, were required for the massive conversion of Chlide a to Chl a. An absolute and novel requirement of Mg2+ for the conversion of Chlide a to Chl a was also demonstrated. In addition to the role of phytol as a substrate for the conversion of Chlide a to Chl a, the data suggested that this alcohol may also be involved in the regulation of the reactions between ALA and Pchlide. It is proposed that during greening, the conversion of Chlide a to Chl a may follow different biosynthetic rates, having different substrate and cofactor requirements, depending on the stage of plastid development.
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  • 134
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    Biotechnology and Bioengineering 26 (1984), S. 497-502 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In studying plasmid instability in recombinant microorganisms, Escherichia coli MV 12[p VH5] and MV 12 trpR[p VH5] harboring trp operon were used as experimental model systems. The host with the trp repression system was partially derepressed by 3-beta-indoleacrylic acid. The results from kinetic analysis of plasmid instability showed that the stability of p VH5 and the growth rate of MV 12[p VH5] decreased rapidly in presence of 3-beta-indoleacrylic acid at a concentration higher than 10 μg/mL, but beyond 30 g/mL no significant change was observed. This suggests that Trp- variants from MV 12[p VH5] could be produced from the host cells at a different frequency depending on the physiological condition. In another system, MV 12 trpR[p VH5] which was constructed by conjugation of E. coli MV 12[p VH5] with E. coli CSH61, the plasmid stability was much lower and the frequency of Trp- cell production was about 10 times higher as compared with the MV 12[p VH5] when treated with 3-beta-indoleacrylic acid. A kinetic model representing the plasmid instability was derived, and a fairly good agreement with the experimental results was found. The fraction of plasmid-free cell (or negative variant) shows a different time course profile depending on the segregation coefficient (a, production rate of negative variants from positive cells during one generation), growth ratio (G, the ratio of growth rates of negative variants to positive cells), and other parameters. The negative variant fraction continues to increase (“run away” type) or it approaches to a finite value (“settling” type) depending on the relative values of a and G.
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  • 135
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    Biotechnology and Bioengineering 26 (1984), S. 513-517 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Adsorption of water and ethanol on four starches has been studied in the temperature range of 50-90°C. The results show that adsorption of water on starch-based materials is enhanced when the amount of amylopectin is highest. Adsorption of ethanol is not significantly affected by the kind of starch used. Heats of adsorption calculated from retention data are in the range from -9.3 to -13.7 kcal/g mol for water and -5.6 to -6.76 kcal/g mol for ethanol. Calculated free energies of adsorption suggest that adsorption is most spontaneous at lower temperatures as expected.
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  • 136
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    Biotechnology and Bioengineering 26 (1984), S. 546-550 
    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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  • 137
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    Biotechnology and Bioengineering 26 (1984), S. 564-564 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 138
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    Biotechnology and Bioengineering 26 (1984), S. 973-981 
    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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  • 139
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    Biotechnology and Bioengineering 26 (1984), S. 982-987 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Poly-β-hydroxybutyrate (PHB) accumulates in individual cells of Alcaligenes eutrophus in the form of refractile bodies which alter the light-scattering properties of individual cells. Flow cytometry has been applied to measure the distributions of single-cell light-scattering intensity in Alc. eutrophus populations during batch cultivation of the organism. These measurements clearly identify heterogeneities in the inoculum which influence the lag interval prior to beginning of exponential growth. Light-scattering distributions show greater homogeneity and are extremely similar during balanced, exponential growth. After exhaustion of the nitrogen source and with carbon source still available, significant PHB accumulations occur and the flow cytometry measurements reveal extreme heterogeneity in single-cell light-scattering properties. These measurements clearly demonstrate the potential advantages of single-cell light-scattering measurements by flow cytometry for analysis and control of certain fermentation processes. Single-cell light-scat light-scattering measurements in conjunction with flow sorting instrumentation have been applied to demonstrate enrichment of PHB-producing cells, initially present in a number concentration of 0.01%by a factor of 300 in a single pass. Flow cytometry-cell sorting technology should find significant application in strain improvement and mutant selection.
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  • 140
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    Biotechnology and Bioengineering 26 (1984), S. 620-622 
    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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  • 141
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    Biotechnology and Bioengineering 26 (1984), S. 613-619 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Batch growth tests were performed under both replicating and nonproliferating (no nitrogen source in medium) conditions with acclimated heterogenous populations that utilized phenol as a sole source of carbon and energy. It was shown that the acclimated populations could efficiently remove the toxic waste component phenol under nonproliferating conditions by utilizing an oxidative assimilation mechanism. The phenol was assimilated and converted into nonnitrogenous storage products. During the assimilation process, the cells had a tendency to excrete some product (nonsubstrate) chemical oxygen demand (COD). Bench-scale oxidative assimilation units were operated by sequentially feeding a carbon source (phenol) and nitrogen source (ammonium sulfate) to heterogeneous populations. This demonstrated that, subsequent to the addition of the nitrogen source to the medium, the cells utilized the stored carbon for replication. Four of these units were operated at different phenol COD-to-ammonia-nitrogen ratios of 10:1, 20:1, 40:1, and 50:1. All of these units demonstrated excellent removal of phenol using an oxidative assimilation mechanism. These results suggested the feasibility of utilizing a continuous flow oxidative assimilation process for the treatment of nitrogen-deficient phenolic wastes. This process would be advantageous over conventional treatment processes in that it would realize a savings in chemical costs (ammonia as nitrogen source) and prevent leakage of excess ammonia from the system.
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  • 142
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    Biotechnology and Bioengineering 26 (1984), S. 665-669 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Single- and double-stranded DNA were immobilized on films of highly polymerized collagen by a covalent process. The coupling was efficient at an acidic pH with an optimum at pH 5, while preventing the collagen film from any damage. In addition, no leakage occurred, so it was possible to use this DNA-coated collagen film as an immunoadsorbent. Therefore the findings reported here suggest that the acyl-azide procedure is also suitable for DNA binding on a proteinic support. Promising results in specific clearance of DNA antibodies were obtained in vitro.
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  • 143
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    Biotechnology and Bioengineering 26 (1984), S. 658-664 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The covalent coupling of an invertase from baker's yeast onto an agricultural by-product, corn grits, has been developed. The optimal conditions for each step of the chemical modification of the support have been determined: oxidation with sodium metaperiodate, amination with ethylenediamine, reduction with sodium cyanoborohydride, and activation with glutaraldehyde. Activities up to 7.2 × 104 μmol reducing sugars produced/min g support could thus be achieved. Invertase coupling onto corn grits yields a derivative with a 25 times higher activity than when coupling this enzyme onto porous silica. The operational stability of invertase immobilized onto corn stover was found to be very high, with a half-life of up to 365 days at 40°C when using a 2M sucrose solution as substrate. This immobilization method could be easily scaled up to the preparation of 10 kg of invertase derivative.
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  • 144
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    Biotechnology and Bioengineering 26 (1984), S. 654-657 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous cooker prototypes of very simple design, using electricity as a primary energy source, were developed for the process of cooking and liquefaction of starch suspensions. Previous work on equipment using microwave dielectric heating has already been reported. Results of energy consumption as low as 330 kcal/kg based on starch content were achieved. Considering these results and looking for new solutions or engineering concepts, the authors have been investigating the possibility of using electric energy at 60 Hz for direct resistive heating, in which the starch suspension is the proper “resistor.”The most important results of energetic yield obtained until now, working in a continuous process of cooking-liquefaction, are not larger than 235 kcal (272 Wh)/kg based on starch content. These results were obtained using a commercial grade α-amylase from B. subtillis, working with temperatures ranging from 70 to 75°C, and with residence times in the reactor not greater than 1.5 min. The experiments of saccharification and fermentation accomplished as a test for the efficiency of this heating technique gave good results (as with a conventional technique) and thus enabled us to proceed with the studies.
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  • 145
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    Biotechnology and Bioengineering 26 (1984), S. 719-726 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of methanol dispersion and fluid mixing upon respiratory patterns observed during unlimited fedbatch growth of the methylotrophic bacterium Methylophilus methylotrophus has been investigated. A concentric tube air-lift fermenter was employed for which the mixing and fluid circulation patterns have been well characterized. Respiratory quotients showed a marked dependence upon the position in the vessel at which methanol was injected, the volumetric rate of such methanol addition, the fluid circulation time, and the local mixing behavior; the latter two factors of which are both determined by the air throughput. Such variations are discussed on the basis of simple mixing concepts and observations of fluid dispersion.
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  • 146
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    Biotechnology and Bioengineering 26 (1984), S. 753-757 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The products of cellulose hydrolysis, glucose and cellobiose, caused noncompetitive inhibition patterns to be exhibited when Thermomonospora sp. YX cellulase hydrolyzed dyed cellulose. The glucose binding constant, β1, was 0.00683 ± 0.00031 L/g and the cellobiose binding constant, β2, was 0.095 ± 0.0058 L/g. Thus, cellobiose was about 14 times more inhibitory than glucose.
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  • 147
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    Biotechnology and Bioengineering 26 (1984), S. 764-770 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrogen-oxidizing bacterium, Alcaligenes eutrophus (ATCC 17707), was grown in chemostat culture with gas-phase (hydrogen, oxygen, and carbon dioxide) and liquid-phase (mineral nutrients) feedstreams; data were used to generate an analytical form for the specific growth rate equation. Model parameters obtained include Monod rate parameters for dissolved hydrogen and oxygen gases, yield coefficients, and specific maintenance rates under conditions of hydrogen or oxygen limitations. These values are similar to some obtained previously by Ohi et al. for another hydrogen bacterium. The observed increase in specific maintenance rates under hydrogen-versus-oxygen-limited culture may be associated with hydrogenase deactivation by oxygen.
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  • 148
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    Biotechnology and Bioengineering 26 (1984), S. 781-787 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lignocellulose containing 62% cellulose was prepared from corn residue by dilute acid hydrolysis using 5% H2SO4 at 90°C. The lignocellulose was then treated with a cellulose solvent consisting of a ferric sodium tartrate complex in 1.5N sodium hydroxide at levels ranging from 4:1 to 12:1 (solvent volume: corn residue lignocellulose) or a 1.5N sodium hydroxide solution alone. Subsequent hydrolysis with cellulase enzymes from Trichoderma reesei gave cellulose conversions which were two to three times higher than untreated lignocellulose (30%) and approached 90% conversion after 24 h in the best cases. It was found that increasing cellulase enzyme levels from 3.74 lU/g lignocellulose to 7.71 lU/g lignocellulose increased cellulose conversion by 50% at all pretreatment conditions, while an increase from 7.71 to 10.1 lU/g gave only an additional 5-10% increase. Pretreatment with sodium hydroxide resulted in 5-25% lower conversions than observed for cellulose treated with the solvent, depending on enzyme levels and treatment levels. At high enzyme levels, sodium hydroxide pretreatment is almost as effective in enhancing cellulose conversion after 24 h as is pretreatment using the cellulose solvent.
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  • 149
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    Biotechnology and Bioengineering 26 (1984), S. 797-799 
    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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  • 150
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    Biotechnology and Bioengineering 26 (1984), S. 805-806 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 151
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    Biotechnology and Bioengineering 26 (1984), S. 811-813 
    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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  • 152
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    Biotechnology and Bioengineering 26 (1984), S. 988-991 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been demonstrated that the dilution of samples prior to the carboxymethylcellulase and xylanase assays causes serious discrepancies in the numerical values obtained for the enzyme activities. Even when the sample is assayed with the identical procedure, one could obtain different numerical values of the enzyme activity U depending on how much this sample has been diluted before the enzyme assay. Two crude commercial cellulase samples of Aspergillus niger and Trichoderma viride as well as the culture filtrate of our newly isolated acidophilic fungus have been used for the demonstration. An empirical method for reporting the cellulolytic activity by taking into account this dilution effect is proposed.
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  • 153
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    Biotechnology and Bioengineering 26 (1984), S. 1176-1188 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An integrated approach is presented for the on-line estimation of the state of a biochemical reactor from presently attainable real-time measurements. Elemental and macroscopic balances are used for the determination of the total rate of growth and state-of-the-art estimation techniques are subsequently employed for the elimination of process and measurement noises and the estimation of state variables and unknown culture parameters. The proposed approach is very flexible in that as new sensors become available they can be easily incorporated within the present framework to estimate new variables or improve the accuray of the old ones. The method does not require any model for the growth kinetics and is very successful in accurately estimating the above variables in the presence of intense noise and under both steady-state and transient conditions. State estimates obtained by the presented method can be used for the development of adaptive optimal control schemes as well as for basic studies of the characteristic properties of microbial cultures.
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  • 154
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    Biotechnology and Bioengineering 26 (1984), S. 1219-1222 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lignocellulose materials were pretreated by methods known to improve enzymatic saccharification, and the percentage crystallinity (x-ray diffraction) and degree of polymerization were measured. It was observed that although the percentage crystallinity of cellulose was not altered by alkaline explosion (AE), carbon dioxide explosion (CE), ozone, and sodium chlorite treatment, very great increases were obtained in the extent of enzymatic saccharification. All the pretreatments studied except sodium chlorite caused significant reduction in degree of polymerization. It appears likely that the rate and extent of saccharification is governed by particle size, surface area, and degree of polymerization, since crystallinity effects alone do not explain the observed trends in the hydrolysis data.
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  • 155
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    Biotechnology and Bioengineering 26 (1984), S. 1239-1244 
    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 algorithm for predicting BOD5 from the dissolved oxygen (DO) concentration after a relatively short incubation period is presented and evaluated experimentally. Test runs on synthetic and experimentally derived raw data suggest that BOD5 can be predicted to within 15% ca. 36 h. The method can be improved by filtering out, via a digital filter, noise from the raw data. The suggested algorithm does not require elaborate computations or large data storage and can therefore be implemented on a low-cost microcomputer for fast on-line determination of BOD5.
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  • 156
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    Biotechnology and Bioengineering 26 (1984) 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 157
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    Biotechnology and Bioengineering 26 (1984), S. 1265-1271 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Marine microalgae were grown in multispecies continuous cultures. Under carbon dioxide limitation, blue-green algae dominated. Under nitrate and light limitation, species dominance depended on the initial conditions. When the inoculum consisted primarily of blue-green algae with smaller amounts of other species, blue-green algae and pennate diatoms dominated. When the inoculum consisted of equal amounts of all species, green flagellates and pennate diatoms dominated. Green flagellates and blue-green algae were incompatible and never shared dominance. When nutrient limitations were overcome, the productivity of seawater was increased 100-fold before light limitation occurred. The productivity could be further increased by reducing photorespiration in the culture. The dilution rates studied (0.1, 0.2, and 0.4 day-1) had no effect on species dominance, nor did the higher dilution rates select for smaller cells. The maximum productivity occurred at a dilution rate of 0.2 day-1. Temperature had the greatest effect on species dominance, with green flagellates, pennate diatoms, and blue-green algae dominating at 20°C and only blue-green algae dominating at 35°C. The productivity at 35°C was lower than that at 20°C because of the lower solubility of carbon dioxide at higher temperatures. At 10% salinity, green flagellates and pennate diatoms dominated. The productivity at this salinity was 50% that obtained at the salinity of seawater (3.5%). At 25% salinity, only the green flagellate, Dunaliella salina, survived at a productivity of 1% that obtained at the salinity of seawater.
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  • 158
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    Biotechnology and Bioengineering 26 (1984), S. 1313-1322 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The photosynthetic growth action spectrum of a green alga at three bands of visible light (blue, orange, and red) at fixed quanta input and under light-limiting conditions was measured in a batch cultivation system. Quantum efficiencies (biomass dry weight increment per quanta absorbed) were better in the yellow-red region than in the blue region. Results served as a basis for the design and optimization of a dye system that would shift the energy of solar radiation to the required wavelength range by absorbing ultraviolet to blue radiation and emitting in the yellow-red, thus enhancing algae growth. Direct incorporation of dyes into the growth medium, although theoretically expected to enhance growth, in fact resulted in dye decomposition, toxicity to algae and consequently in growth inhibition. Indirect application of dyes in a double tubular reactor (algae inside and dye solution outside) demonstrated growth enhancement for certain dyes with high quantum yields and stability, which had suitable absorption/emission spectra for artificial light sources used. The maximum indirect growth enhancement was obtained using rhodamine 6G at a concentration of 3×10-5M with tungsten filament lamp sources.
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  • 159
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    Biotechnology and Bioengineering 26 (1984), S. 1343-1351 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The immobilization of pullulanase and β-amylase on soluble polysaccharides (dextrans and amylose) has been carried out. The method used for coupling the enzymes to the carbohydrate support involves limited periodate oxidation of the polysaccharide followed by reductive alkylation with sodium cyanoborohydride or borohydride. The influence of the degree of functionalization of the carbohydrate, the incubation time, the nature of the reducing agent and, for the dextrans studied, their molecular weight, on the properties of the conjugate were studied. We have observed an apparent correlation between the molecular weight of the glycoprotein conjugates formed and their thermal stability, resistance to urea denaturation and their kinetic parameters. By selecting the proper experimental conditions leading to conjugates with maximum thermal stabilities, it has also been shown that β-amylase conjugates can hydrolyze starch at a temperature 20°C higher than the corresponding value for the native enzyme. This result demonstrates that conjugation may result in modified enzymes leaving a high operational stability at elevated temperatures. We suggest that the immobilization method presented in this article represents an approach to the stabilization of enzymes employed at an industrial level, which may be of general application.
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  • 160
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    Biotechnology and Bioengineering 26 (1984), S. 1383-1389 
    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 based on molecular mechanisms for regulation of the lactose (lac) operon in Escherichia coli has been extended and applied to investigate the lac promoter function in the chromosome and in multicopy plasmids. The model simulates the influence of certain host cell mutations and also mutations in the lac promoter sequence in the chromosome in reasonable agreement with previous experimental measurements. The effect of the plasmid copy number and the cloning vector size on the promoter function of a cloned lac regulatory sequence in multicopy plasmids has also been examined. Model results indicate that the efficiency of the cloned lac promoter function is significantly decreased as the number of promoters per cloning vector and size of the vector are increased. The simulation results predict a maximum in the cloned gene transcription rate with respect to the plasmid copy number.
    Additional Material: 4 Ill.
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  • 161
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    Biotechnology and Bioengineering 26 (1984) 
    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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  • 162
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hydroxylation in the 11 α-position in the progesterone molecule employing immobilized spores of Aspergillus ochraceus strain No. G8 (CDRI catalogue No.) was achieved. For immobilization the activity of the spores was evaluated on a variety of matrices such as alginate beads, epoxy resin beads, polyacrylamide gel, and collagen. Spores entrapped in polyacrylamide gel were found to be the most active. Studies of various parameters, e.g. monomer content, cell loading capacity, optimum pH, temperature, and substrate concentration, were carried out on polyacrylamide gel. In polyacrylamide, the entrapped spores normal decay pattern, as indicated by loss of activity, was observed after four uses. At the end of 15 cycles, the residual activity was found to be 18% of the original. It was possible to regenerate the activity by incubating the preparation in a nutrient medium. The regenerated spores showed increasing rate of loss of activity upon recycling.
    Additional Material: 8 Ill.
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  • 163
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lipase from Candida cylindracea has been found to be a highly stereospecific catalyst suitable for preparative resolution of racemic acids and alcohols. Using (R, S)-2-(p-chlorophenoxy) propionic acid (whose R isomer is a herbicide) and (R, S)-sec-butanol (a versatile synthon) as model compounds, three alternative approaches to lipase-catalyzed resolutions - asymmetric hydrolysis, esterification, and transesterification - have been compared. Enzymatic esterification in biphasic systems has been ruled out for preparative resolutions because addition of the acids lowers the pH of the aqueous phase thereby greatly reducing the efficiency of the procedure. Both enzymatic hydrolysis and biphasic transesterification afforded resolution of the racemates on a gram scale. From the standpoint of productivity, ease of product separation, and the amount of steps required, lipasecatalyzed asymmetric hydrolysis has been judged to be superior for the practical resolution of racemic acids, and lipase-catalyzed asymmetric transesterification to be the method of choice for the practical resolution of racemic alcohols.
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  • 164
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    Biotechnology and Bioengineering 26 (1984), S. 1252-1257 
    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 (Ws)was treated in a pilot-scale continuous mixer to disrupt the lignin-hemicellulose-cellulose (LHC) complex. An efficient and practical method was desired to remove lignin and hemicellulose (pentosans)rapidly and efficiently from the lignocellulose complex and to make the cellulose accessible to enzymatic hydrolysis. Milled WS in the presence of various chemicals in aqueous solutions was extruded from the mixer under several processing conditions. Chemicals used were sodium hydroxide (NaOH) sodium sulfide (Na2S), anthraquinone (AQ), anthrahydroquinone (AHQ), hexamethylenediamine (HMDA), hexamethylenetetramine (HMTA) hydrogen peroxide (H2O2), and ferrous ammonium sulfate (FAS), which were used alone and in selected combinations. Concomitantly, WS was treated in laboratory batches using similar reaction conditions, except for mixing and shearing. In extrusion treatments of WS at 20% concentration at 97°C for 5.5 min with NaOH (15.7%, dry WS basis), NaOH (15.7%) + AHQ (0.3%), and NaOH (12.7%) + Na2S (5.0%), 64-72% of the WS lignin and 36-43% of the pentosans were removed from aqueously washed extrudates (residues). This compares with 46-56% and 23-27%, respectively, for batch treatments. AHQ and Na2S enhanced delignification. Cellulase treatment of the residues, which contained about 99%of the WS cellulose, converted 90-92%of the cellulose to glucose compared with 61-69%for the batch pretreatments. Treatments of WS with amines and H2O2 (alone or combined with NaOH)were less effective for LHC disruption. In all instances the relatively high-shear extrusion treatments were superior to the laboratory-batch treatments.
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  • 165
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    Biotechnology and Bioengineering 26 (1984), S. 1288-1293 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to achieve synchronization of cell division by continuous phasing, the growth of enteric bacteria has been limited by inorganic phosphate. After a short starvation, the culture was automatically diluted twofold so that the limiting nutrient allowed for one doubling exactly. An automatic device was designed to carry out repeated cycles of growth, starvation and dilution with adjustable periodicity. After 12-24 automatic cycles, which were usually achieved largely overnight, synchronous cell divisions could be observed for several generations in nonlimiting culture conditions. When portions of the phased culture were frozen and kept at low temperature for periods up to several months, these freeze-preserved populations exhibited a synchronous growth upon thawing and cultivation. This technique has thus the potential of providing synchronized cultures of a variety of bacterial strains at the desired time.
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  • 166
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    Biotechnology and Bioengineering 26 (1984), S. 1323-1329 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nonliving biomass of nine Rhizopus species effectively sequestered the uranyl ion from solution, taking up 150-250 mg U/g dry cells at 300 ppm U equilibrium concentration in solution, and 100-160 mg U/g dry cells with 100 ppm U in solution. The affinity of this biosorbent for the uranyl ion was found to be affected by timing of harvesting and medium composition. Uptake of the uranyl ion by nonliving biomass of Rhizopus oligosporus was due to ion exchange or complexation, since binding was reversed by the addition of complexing ligands or the reduction of pH to a value less than 2. Uptake isotherms were interpreted in terms of a model of multiple equilibria. At pH ≤ 2, or in the presence of NO3-, Cl-, SO42-, or EDTA (ethylenediamine-tetra-acetate), the quantity of UO22+ that was bound was a constant fraction of that bound at pH 4 in the absence of ligands. This action indicated simple competition for uptake sites between H3O+ and UO22+ for uptake sites, or for UO22+ between the biomass and ligands in solution. If oxalate or thiocyanate was present, however, the complexed species were sequestered by the biomass. Biomass of Rhizopus arrhizus, which grew as pellets, was subsequently used in a packed sorption column where it exchanged hydrogen ions for uranyl ions (2 H+: 1 UO22+). Concentrated uranyl solutions were eluted in sulfuric or nitric acids, and the biomass was reused eight times with no apparent deterioration of the biosorbent.
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  • 167
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    Biotechnology and Bioengineering 26 (1984), S. 1352-1363 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth dynamics of a methanol utilizing bacterium, L3, in batch bioreactors were experimentally investigated. Formaldehyde, a key intermediate of methanol oxidation, is indicated to have a significant role in the complex batch growth behavior of L3. The intricate batch growth dynamics of many microorganisms can be elegantly characterized by examining the specific rates of exchange of nutrients and products between the cells and the cellular environment. Following such an analysis, the batch growth of L3 on methanol was characterized by the presence of unbalanced and balanced growth phases. The nature and significance of nutrient and product concentration profiles or semilog-arithmic profiles of nutrient and product exchange rates during balanced and unbalanced growth phases are also outlined.
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  • 168
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    Biotechnology and Bioengineering 26 (1984), S. 6-11 
    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 Aspergillus parasiticus and accumulation of aflatoxin B1 in the medium that contained antifungal agents were monitored during the growth cycle of the mold. The antifungal agents tested are the food additive (antioxidant), butylated hydroxyanisole (BHA), the pesticide, isoprothiolane, and the antibiotic, nystatin. Growth of the mold was quantified using a newly developed criterion, named the growth coefficient (GC). The GC values were calculated from the growth parameters of the logistic function that fits the growth curve of the mold. At the range of concentrations of additives studied, maxima of growth inhibition were 31.3, 23.1, and 43.6% at 60 ppm of BHA, 70 ppm of isoprothiolane, and 45 units of nystatin/mL, respectively. The ability of the mold to accumulate aflatoxin B1 in its medium [as measured by the accumulation rate constant (α)] In the presence of various levels of the antifungal agents was concentration-dependent. Sixty parts per million of BHA decreased the value of α by 71.7%, 30 units of nystatin/mL was the most effective concentration of that antibiotic and resulted in only 23.5% inhibition, and isoprothiolane at all its levels stimulated elaboration of aflatoxin B1 by the mold.
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  • 169
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    Biotechnology and Bioengineering 26 (1984), S. 37-40 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some properties of the crude lyophilized fibrinolytic enzyme produced by Cochliobolus lunatus in surface culture were studied. Enzyme concentrations over the range from 0.16 to 10.16 mg/mL showed that concentration above a certain level ceased to be the limiting factor controlling enzyme action. At pH 6.8 and a temperature of 40°C, the fibrinolytic enzyme showed maximal activity at a human fibrin concentration of 2 mg/mL. The optimum pH values for enzyme activity were 6.98 and 7.0, using Sørensen and Mcllvaine buffers, respectively. Fibrinolytic enzymes were isolated from a static culture of Cochliobolus lunatus; isolation was carried out with various agents. Ammonium sulphate yielded the highest recovered fibrinolytic activity. The fraction salted out by precipitation at 25% ammonium sulphate saturation possessed the highest recovered fibrinolytic activity compared to the ammonium sulphate, ethanol, and acetone fractions.
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  • 170
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    Biotechnology and Bioengineering 26 (1984), S. 27-36 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The feasibility of operating a multistage continuous culture of plant cells was demonstrated for Nicotiana tabacum. Cells in the second stage of a two-stage chemostat were morphologically distinct from cells in the first stage or cells in a single-stage unit with a holding time equal to the combined holding times in the two-stage system. Cells in the second stage produced much higher levels of phenolics per unit weight of cells than cells in either the first-stage or single-stage unit. The steady-state was reproduced. When a glucose side stream was fed to the second stage, an increase in apparent cell division was observed with a simultaneous decrease in phenolics productivity. When the toxic precursor phenylalanine was pulsed into the reactor, the quantity of biomass decreased temporarily while phenolic productivity increased. These experiments demonstrate that multistage continuous culture may be useful in increasing secondary metabolite formation in cells and in exploring mechanisms controlling secondary metabolite formation.
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  • 171
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    Biotechnology and Bioengineering 26 (1984), S. 53-58 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The diffusion characteristics of several substrates of varying molecular sizes into and from Ca-alginate gel beads in well-stirred solutions were investigated. The values of the diffusion coefficient (D) of substrates such as glucose, L-tryptophan, and α-lactoalbumin [with molecular weight (MW) less than 2 × 104] into and from the gel beads agreed with those in the water system. Their substrates could diffuse freely into and from the gel beads without disturbance by the pores in the gel beads. The diffusion of their substrates into and from the gel beads was also not disturbed by increasing the Ca-alginate concentration in the beads and the CaCl2 concentration used in the gel preparation. In the case of higher molecular weight substances such as albumin (MW = 6.9 × 104), γ-globulin (MW = 1.54 × 105) and fibrinogen (MW = 3.41 × 105), the diffusion behaviors of the substrates into and from the gel beads were very different. No diffusion of their substrates into the gel beads from solutions was observed, and only albumin was partly absorbed on the surface of the gel beads. The values of D of their substrates from the gel beads into their solutions were smaller than their values in the water system, but all their substrates could diffuse from the gel beads. The diffusion of high molecular weight substrates was limited more strongly by the increase of Ca-alginate concentration in the gel beads than by the increase of the CaCl2 concentration used in the gel preparation. Using these results, the capacity of Ca-alginate gel as a matrix of immobilization was discussed.
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  • 172
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    Biotechnology and Bioengineering 26 (1984), S. 87-91 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous culture studies of Azotobacter vinelandii cells immobilized by ionic adsorption to Cellex E anion exchange resin were conducted under oxygen-limited conditions for comparison to free-cell cultures. Immobilization had little effect upon the specific respiration and sucrose consumption rates as compared to free cells. However, maxima in specific nitrogen fixation rate and nitrogenase activity as a function of dissolved oxygen occurred at a CO2 value of approximately 0.005 mM as opposed to 0.02 mM for free cells. Further, in contrast to free-cell culture, most of the fixed nitrogen appeared in the medium rather than within intact cells. There were strong indications that reproduction of bound cells often resulted in cell lysis accounting for the fixed nitrogen content in solution.
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  • 173
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    Biotechnology and Bioengineering 26 (1984) 
    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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  • 174
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    Biotechnology and Bioengineering 26 (1984), S. 134-141 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The technique of cell immobilization using porous support particles (biomass support particles) has been successfully applied to yeast cells. Two reactor configurations exploiting the use of these particles have been developed and assessed for use in aseptic yeast fermentations. A liquid-fluidized bed fermenter has been devised for use with particles denser than the fermentation liquor whilst a gas-stirred circulating bed fermenter proved suitable for particles of essentially neutral buoyancy. Both systems have been operated successfully for extended periods of continuous operation. The utilization of biomass support particle technology in such reactors provides a practical and robust system for immobilized cell reactors. This technology offers significant opportunities for further development.
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  • 175
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    Biotechnology and Bioengineering 26 (1984), S. 156-166 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental investigation is by far the most effective approach for studying the behavior of physical systems. However, an enzymatic solubilization of vegetable protein is a complex combination of intrinsic problems, of which many are not easily adaptable to experimental investigation. Experimental designs to study enzyme vegetable protein reactions yield data which describe the extramembraneous activity of the immobilized enzyme. In a continuous recycle immobilized enzyme reactor, the microenvironment concentration of the substrate or product in the membrane phase, or the concentrations along the reactor axial length in the bulk phase are not discernible to the experimenter. However, the knowledge of such concentration profiles is important in weighing the significance of such factors as intermembrane diffusion, enzyme loading, wet membrane size, and the mode of operation of the reactor. The simulation of mathematical models, which describe the physical system within the constraints imposed, yields information which is vital to the understanding of the process occurring in the reactor. The kinetics and diffusion of an immobilized thermophilic Penicillium duponti enzyme at pH 3.4-3.7 and 50°C was modeled mathematically. The kinetic parameters were evaluated by fitting a model to experimental data using nonlinear regression analysis. Simulation profiles of the effects of reactor geometry, substrate concentration, membrane thickness, and enzyme leading on the hydrolysis rate are presented. From the profiles generated by the mathematical model, the best operational reactor strategy is recommended.
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  • 176
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    Biotechnology and Bioengineering 26 (1984) 
    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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  • 177
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    Biotechnology and Bioengineering 26 (1984), S. 217-220 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A cross-current flow reactor was operated using sodium alginate gel entrapped yeast cells under growth conditions. Micron-sized silica, incorporated into the biocatalyst particles (1 mm mean diameter) improved mechanical strength and internal surface adhesion. The process showed decreased productivity and stability at 35°C compared to the normal study done at 30°C. The increased number of cross flows diminish the product inhibition effect. The residence time distribution shows that the cross-flow bioreactor system can be approximated to either a train of backmixed fermentors in series or a plug flow fermentor with moderate axial dispersion.
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  • 178
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    Biotechnology and Bioengineering 26 (1984), S. 257-264 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bioconversion of acetic acid to methane by a crude culture of methanogens in a continuous multireactor system was investigated. Culture of methanogens was drawn from an active cow-dung digester (12 days) and was grown in a semisynthetic medium (pH 6.3, 37°C) with acetic acid as the sole carbon source. The solubilities of CO2, HCO3-, and CO32- increased with the rise in pH and exercised considerable influence on the gas composition. Various mechanisms for methanogenesis of acetic acid based on the available pathways were considered. Experimental data were compared with these mechanisms, the best fit was determined, and the corresponding rate expression was identified. This mechanism predicted that, of the total methane produced, 72%;comes from acetic acid directly and 28%;via the CO2 reduction route.
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  • 179
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    Biotechnology and Bioengineering 26 (1984), S. 315-319 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using only wheat bran koji from the Rhizopus strain, raw cassava starch and cassava pellets converted reasonably well to alcohol (ethanol) without cooking at 35°C and pH 4.5-5.0. When the initial broth contained 30 g raw cassava starch, 10 g Rhizopus sp. koji, and 100 mL tap water, 12.1 g of alcohol was recovered by final distillation from fermented broth. In this case, 12.1 g alcohol corresponds to an 85.5% conversion rate based on the theoretical values of the starch content. When the initial broth contained 40 g cassava starch, 14.1 g of alcohol was recovered, where 14.1 g corresponds to a 74.5% conversion rate. The alcoholic fermentation process described in the present work is considered more effective and reasonable than the process using raw starch without cooking reported until now, since the new process makes it unnecessary to add yeast cells and glucoamylase preparation.
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  • 180
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    Biotechnology and Bioengineering 26 (1984), S. 335-339 
    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 dehydration on yield and calorific values has been investigated for oils, hydrocarbons, and polyphenols extracted from leaves of Euphorbia esula/ (leafy spurge). Methods of dehydration employed were with a warm oven (50°C), a hot oven (105°C), at room temperature (25°C), and with freeze drying. Generally, dehydration resulted in a loss of yield for all extractives. Noteworthy exceptions were oil yields from the warm-oven- or air-dried biomass which did not differ significantly from fresh tissue. Significant differences in calorific values (range 4643-5192 cal/g) were observed for each category of whole leafy biomass dehydrated as indicated above. Dehydration reduced the calorific value of oils (range 9483-10,095 cal/g) but tended to increase the calorific values of polyphenols (range 4178-6033 cal/g). NMR spectroscopy of the oil fraction suggested that dehydration did not grossly alter the composition of oils, despite differences in yield and calorific values.
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  • 181
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    Biotechnology and Bioengineering 26 (1984), S. 362-369 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is known that 2,3-butanediol is a potentially valuable chemical feedstock that can be produced from the sugars present in hemicellulose and celluose hydrolysates. Klebsiella oxytoca is able to ferment most pentoses, hexoses, and disaccharides. Butanediol appears to be a primary metabolite, excreted as a product of energy methabolism. The theoretical maximum yield of butanediol from monosaccharides is 0.50 g/g. This article describes the effects of pH, xylose concentration, and the oxygen transfer rate on the bioconversion of D-xylose to 2,3-butanediol. Product inhibition by butanediol is also examined. The most important variable affecting the kinetics of this system appears to be the oxygen transfer rate. A higher oxygen supply favors the formation of cell mass at the expense of butanediol. Decreasing the oxygen supply rate increases the butanediol yield, but decreases the overall conversion rate due to a lower cell concentration.
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  • 182
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    Biotechnology and Bioengineering 26 (1984), S. 382-385 
    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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  • 183
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    Biotechnology and Bioengineering 26 (1984), S. 390-391 
    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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  • 184
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    Biotechnology and Bioengineering 26 (1984), S. 394-396 
    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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    Biotechnology and Bioengineering 26 (1984), S. 419-425 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The implementation of adaptive control for a fed-batch culture in order to maximize the output of product based on a self-adjusting model is discussed in the present work. Optimization methods were applied to the generalized mathematical model of a fed-batch fermentation process to determine control algorithms that could be used for on-line process control. The efficiency of the proposed adaptive algorithms was investigated by simulating a model system. The model of amylotytic enzyme fermentation that was proposed by the authors was taken from a real process. Dynamic modelling has shown that the main problem of realization is connected with the on-line identification of the adaptive model's parameters. To avoid this problem, we have introduced special limitations on the parameters' time variations that increased the convergence of the identification algorithm. The results of the investigation have shown the efficiency of the proposed adaptive algorithms, and the results of this work should be investigated for real process control.
    Additional Material: 9 Ill.
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  • 186
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    Biotechnology and Bioengineering 26 (1984), S. 1155-1166 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inhibition by secondary feed components can limit productivity and restrict process options for the production of ethanol by fermentation. New fermentation processes (such as vacuum or extractive fermentation), while selectively removing ethanol, can concentrate nonmetabolized feed components in the remaining broth. Stillage recycle to reduce stillage waste treatment results in the buildup of nonmetabolized feed components. Continuous culture experiments are presented establishing an inhibition order: CaCl2, (NH4)2×SO4 〉 NaCl, NH4Cl 〉 KH2PO4 〉 xylose, MgCl2 〉 MgSO4 〉 KCl. Reduction of the water activity alone is not an adequate predictor of the variation in inhibitory concentration among the different components tested. As a general trend, specific ethanol productivity increases and cell production decreases as inhibitors are added at higher concentration. We postulate that these results can be interpreted in terms of an increase in energy requirements for cell maintenance under hypertonic (stressed) conditions. Ion and carbohydrate transport and specific toxic effects are reviewed as they relate to the postulated inhibition mechanism. Glycerol production increases under hypertonic conditions and glycerol is postulated to function as a nontoxic osmoregulator. Calcium was the most inhibitory component tested, causing an 80%decline in cell mass production at 0.23 mol Ca2+/L and calcium is present at substantial concentration in many carbohydrate sources. For a typical final cane molasses feed, stillage recycle must be limited to less than onethird of the feed rate; otherwise inhibitory effects will be observed.
    Additional Material: 10 Ill.
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  • 187
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    Biotechnology and Bioengineering 26 (1984), S. 1198-1208 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The applicability of the respiratory quotient measurement, a heat evolution measurement, and a commonly observed correlation between the respiratory quotient and product yield to on-line bioreactor identification and control were inspected. It was found that singularities can exist in macroscopic balances used in connection with these measurements or the correlation, rendering them inappropriate for process parameter identification. By the formulation of generalized metabolic pathways together with NADH2 and ATP balances, general rules were derived for identifying conditions causing singularities. Thus it was found that, in addition to other less probable situations, the RQ measurement becomes impractical when the degree of reductance of the substrate is identical to that of the product, if any, and close to that of biomass. The correlation always presents sensitivity problems because it is nearly a linear combination of the elemental balances and the balance arising from the definition of the respiratory quotient. The heat evolution measurement nearly always presents sensitivity problems because of a linear dependence between the enthalpy balance and the degree of reductance, or NADH2, balance due to the regularity that the degrees of reductance of most biological compounds are proportional to their heats of combustion. Problems are considered and suggestions made for replacing the measurements, when inapplicable, or the correlation with an ATP balance. Experimental results and numerical studies on the fermentations of yeast and E. coli support the theoretically derived rules.
    Additional Material: 5 Ill.
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  • 188
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    Biotechnology and Bioengineering 26 (1984), S. 1233-1238 
    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 study of the enzymatic hydrolysis of two celluloses with different structural features was performed at various temperatures (26-50°C). The enzymatic system consisted of three types of enzymes: E1 - β-1,4-glucan glucanohydrolase; E2 - β-1,4-glucan cellobiohydrolase; and E3 - β-glucosidase. A mathematical model for the mechanism of the hydrolysis of cellulosic materials catalyzed by a multienzymatic system was checked and a good rationalization of the experimental results was achieved. Uncompetitive and competitive glucose inhibition on E1 and E2, respectively, appeared to occur for both substrates. Inhibition by cellobiose was checked at 34°C on one substrate. The Vmax, Km, and glucose inhibition constants were optimized and their dependence on temperature determined.
    Additional Material: 3 Ill.
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  • 189
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    Biotechnology and Bioengineering 26 (1984), S. 1261-1264 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 190
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    Biotechnology and Bioengineering 26 (1984), S. 1282-1287 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rationale for efficient light absorption by algae at a production unit is given and design details of an intensive thin-layer technology outdoor (2.11 m2) unit are presented. Data on productivity under extreme conditions were collected. Maximum productivity data are close to those reported in the literature for similar geographic areas.
    Additional Material: 2 Ill.
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  • 191
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    Biotechnology and Bioengineering 26 (1984), S. 1306-1312 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Frog epidermis tyrosinase has been immobilized on Enzacryl-AA (a polyacrylamide-based support) and CPGzirclad-Arylamine (a controlled pore glass support) in order to stabilize the tyrosine hydroxylase activity of the enzyme; in this way, the immobilized enzyme could be used to synthesize L-dopa from L-tyrosine. The activity immobilization yield YIMEact (higher than 86%), coupling efficiency (up to 90%), storage stability (no loss in 120 days), and reaction stability (t1/2 was higher than 20 h in column reactors) were measured for tyrosinase after its immobilization. The results showed a noticeable improvement (in immobilization yield, coupling efficiency, and storage and operational stabilities) over previous reports in which tyrosinase was immobilized for L-dopa production. The activity and stability of immobilized enzyme preparations working in three different reactor types have been compared when used in equivalent conditions with respect to a new proposed parameter of the reactor (Rp), which allows different reactor configurations to be related to the productivity of the reactor during its useful life time. The characteristic reaction inactivation which soluble tyrosinase shows after a short reaction time has been avoided by immobilization, and the stabilization was enhanced by the presence of ascorbate. However, another inactivation process appeared after a prolonged use of the immobilized enzyme. The effects of reactor type and operating conditions on immobilized enzyme activity and stability are discussed.
    Additional Material: 8 Ill.
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  • 192
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    Biotechnology and Bioengineering 26 (1984), S. 1334-1342 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hydrogen photoproduction from water by Scenedesmus cells was achieved in the presence of reagents that combine reversibly with oxygen. The oxygen can be subsequently released, and H2 and O2 are obtained in the 2:1 ratio expected for H2O photolysis. This was accomplished in an experimental design which facilitates rapid transfer of gases and the use of a variety of water-soluble and DMSO-soluble chelates of cobalt which combine reversibly with oxygen.
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  • 193
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    Biotechnology and Bioengineering 26 (1984), S. 1390-1392 
    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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  • 194
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    Biotechnology and Bioengineering 26 (1984), S. 1395-1397 
    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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  • 195
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    Biotechnology and Bioengineering 26 (1984), S. 1418-1424 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aerobic glucose metabolism by Pseudomonas aeruginosa in steady-state biofilms at various substrate loading rates and reactor dilution rates was investigated. Variables monitored were substrate (glucose), biofilm cellular density, biofilm extracellular polymeric substance (EPS) density, and suspended cellular and EPS concentrations. A mathematical model developed to describe the system was compared to experimental data. Intrinsic yield and rate coefficients included in the model were obtained from suspended continuous culture studies of glucose metabolism by P. aeruginosa. Experimental data compared well with the mathematical model, suggesting that P. aeruginosa does not behave differently in steady-state biofilm cultures, where diffusional resistance is negligible, than in suspended cultures. This implies that kinetic and stoichiometric coefficients for P. aeruginosa derived in suspended continuous culture can be used to describe steady-state biofilm processes.
    Additional Material: 7 Ill.
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  • 196
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    Biotechnology and Bioengineering 26 (1984), S. 1425-1429 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two-phase anaerobic digestion of liquid swine manure has been developed with options for single-cell protein (SCP) or methane production. In the acidogenic phase at two to four days retention time, and 2.5-7.0% dry matter (DM) concentration, 8-46% of the volatile solids was solubilized. Maximum reactor capacity was 3.86 g/L at 7.0% DM concentration, but optimal operation was achieved at 4.5% DM concentration at four days retention time. The second methanogenic phase was operated continuously and had a maximum specific methane production rate of 0.70 L/L day at 12 days retention time. With recirculation, the rate was 1.16 L/L day at 8.5 days retention time with 52.7% conversion of organic matter. Maximum digestibility was 66% of the lignin free organic matter.
    Additional Material: 6 Ill.
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  • 197
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    Biotechnology and Bioengineering 26 (1984), S. 1465-1474 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Steam-treated wheat straw at a 70% (w/w) moisture level was subjected to solid substrate fermentation (SSF) with Trichoderma reesei (Riga, USSR) or a mixed culture of T. reesei and Endomycopsis fibuliger (R-574) in fermentation equipment of various design: some with mixing, some with stationary layers, including a mixedlayer 1.5-m3 pilot plant scale fermenter. The best protein productivity was obtained in stationary layer fermenters with a product containing 13% protein. The main limitations of lignocellulose SSF, such as hindrance of fungal growth, limiting accessibility and availability of substrate, and difficulty in moisture and heat control, were analyzed. The technological parameters of SSF, submerged fermentation, and alternate lignocellulose conversion processes were compared. The SSF had lower overall efficiency but higher product concentration per reaction volume than other conversion schemes.
    Additional Material: 3 Ill.
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  • 198
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    Biotechnology and Bioengineering 26 (1984), S. 1506-1507 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 199
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    Biotechnology and Bioengineering 26 (1984), S. 66-73 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of growth rate on Escherichia coli plasmid content and expression of a cloned-gene product has been described by a mathematical model based upon the molecular mechanism of λdv plasmid replication and known relationships between growth rate and transcription and translation activities of the host cell. The model simulates correctly decreases in plasmid content with increasing growth rate as observed experimentally for pBR322, NR1, R1, and Col E1 plasmids. A maximum with respect to growth rate in intracellular product accumulation is indicated by the model, as is a transient overshoot in product concentration following a shift from smaller to larger growth rate. Available data, although very limited, show the same trends. These results, obtained without parameter or kinetic form adjustments or manipulation, clearly illustrate the advantages of kinetic descriptions of recombinant systems based upon the pertinent molecular mechanisms.
    Additional Material: 4 Ill.
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  • 200
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    Biotechnology and Bioengineering 26 (1984), S. 92-99 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The leaching of pyrite sulfur from coal employing Thiobacillus Ferrooxidans was studied in a continuous stirred tank reactor at a variety of dilution rates (0.02-0.11 h-1) and coal surface areas (0.25-1.0 m2/mL). The bacterial leaching rate was found to increase with increasing coal surface area concentration and increasing dilution rate. The bacterial concentration on the coal surface was related to the bacterial concentration in solution by a irreversible second-order (of the second kind) kinetic equation. The concentration of bacteria on the coal in all experiments was the concentration at saturation. Step changes in the coal concentration were observed to result in dramatic declines in bacterial concentration in solution. A bacterial mass balance model was employed to calculate the specific growth rate on the solid which was observed to increase with increasing dilution rate.
    Additional Material: 8 Ill.
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