Library

Notes: No Abstracts.

Notes: No Abstracts.

Notes: No Abstracts.

Notes: An enzymic characteristic of Novo dextranase was presented. In addition to a high dextranolytic activity (7,200 U/ml), the crude enzyme also contained small amounts of protease, glucoamylase, polygalacturonase, carboxymethylcellulase, laminarinase and chitinase. A highly purified dextranase was then simply separated from a commercial preparation by column chromatographies on DEAE-Sepharose, CM-Sepharose, and by chromatofocussing on Polybuffer Exchanger PBE-94. The enzyme was recovered with an over 200-fold increase in specific activity and a yield of 84%. The final preparation was homogeneous, as observed during high performance liquid chromatography (HPLC). Size-exclusion HPLC indicated that dextranase had a molecular mass of 35 kDa and its isoelectric point, established by chromatofocussing, was 4.85. Analysis of the dextran break-down products indicated that purified dextranase represents an endolytic mode of action, and isomaltose and isomaltotriose were identified as the main reducing sugars of dextran hydrolysis. The enzyme was then covalently coupled to the silanized porous glass beads modified by glutaraldehyde (Carrier I) or carbodiimide (Carrier II). It was shown that immobilization of dextranase gave optimum pH and temperature ranges from 5.4 to 5.7 and from 50°C to 60°C, respectively. The affinity of the enzyme to the substrate decreased by a factor of more than 13 for dextranase immobilized on Carrier I and increased slightly (about 1.4-times) for the enzyme bound to Carrier II.

Notes: The ability of a mixed natural microbial population, collected in an aerated lagoon treating Fluff pulp effluent and Streptomyces viridosporus strain T7A, to degrade lignosulphonate was evaluated. S. viridosporus growing in a mineral medium containing glycerol (7 g/l) and lignosulphonate (1 g/l) allowed 20% of lignosulphonate to be degraded after 18 days of incubation. A culture of the mixed population on culture medium after S. viridosporus growth was unable to degrade lignosulphonate products. Moreover, antagonism between S. viridosporus and the mixed population or between S. viridosporus and the isolated strains from this population was observed. The enhancement of lignosulphonate biodegradation by naturally occurring microorganisms in association with S. viridosporus (bioaugmentation strategy) seems to be difficult.

Notes: No Abstracts.

Notes: In fixed-bed bioreactors, the influence of the oxygen content in the inlet air on the biodegradation of diesel fuel in unsaturated soil/compost mixtures was analyzed at 30°C over a period of 7 weeks. Firstly, a wide range from 0 to 80 vol.% O2 was investigated. Subsequently, the range below 5 vol.% O2 was examined more closely. Over the whole test period of seven weeks, no significant influence of oxygen could be observed above 1 vol. % O2 in the inlet air - either on the decrease of the total contaminants or on the total mineralization. Anaerobic conditions should be avoided for the degradation of diesel fuel. During the test period, the courses of CO2 production varied significantly depending on oxygen supply. Furthermore, a model was developed to estimate the total mineralization as a function of oxygen supply. More investigations are recommended in order to test this model for practical application.

Notes: No Abstracts.

Notes: The formation of reactive groups on polyamide nets (nylon 6) and the subsequent immobilization of glucoamylase were investigated. Different mesh sizes of the nets and two chemical methods of enzyme coupling - i( partial hydrolysis of the polyamide with subsequent glutaraldehyde binding and ii) O-alkylation of the carrier using a treatment with a benzene-methyl sulphate mixture - were used. The reactivity of immobilized glucoamylase (GA) was tested by hydrolysis reactions using 1% starch solutions. The highest reactivity (140 μg glc/)min × cm2 was obtained for methylated nylon samples attached to a glass rod and by coupling glucoamylase on the nylon surface which had been treated with lysine and glutaraldehyde. This method resulted in a more reactive and more stable preparation of immobilized glucoamylase as compared to a simpler method of coupling glutaraldehyde to partially hydrolyzed nylon.

Notes: No Abstracts.

Notes: No Abstracts.

Notes: No Abstracts.

Notes: The cleaning of the exhaust gases of a bioreactor containing volatile hydrocarbons in a bioreactor system with a closed gas circuit is described. The bioreactor system consisted of three different reactor types: a stirred tank which was filled with hydrocarbon-containing waste water to simulate the exhaust gases of a remediation process; a trickle-bed reactor for aerobic treatment of the exhaust gas from the stirred tank; and a photoreactor containing an algae culture which assimilated CO2 from the trickle-bed reactor and also produced O2. With this bioreactor system, it was possible to efficiently remove volatile organic compounds (VOC) from the waste gases. Depending on the type of waste water investigated, elimination rates of 41% to 93% of BTEX (benzene, ethylbenzene, toluene, xylene) and 29% to 53% of VCH (volatile chlorinated hydrocarbons) were obtained. Due to the photosynthesis of the algae in the system's photoreactor, oxygen concentrations between 12% and 18% [v/v], equivalent to about 57% to 83% DOT, were obtained. This concentration permitted the aerobic degradation to be carried out without having to add fresh air. The trickle-bed reactor and the photoreactor worked continuously, whereas the waste water in the stirred bioreactor was replaced in different batches. The accumulation of toxic compounds in the nutrient solutions of the trickle-bed (EC-50 〉 30 g/l) and of the photoreactor (EC-50 〉 35 g/l) was low. Carbon dioxide concentrations in the gas flow were higher than in fresh air (1% to 3% [vol/vol]), but no long-term accumulation of CO2 occurred. This means that the algae in the photoreactor were active enough to assimilate the CO2 which had been produced. They were also able to produce sufficient oxygen for aerobic hydrocarbon degradation. The system described is a first step towards treating waste gases which results from the bioremediation of hydrocarbon-contaminated media in a closed gas circuit without any emission (e.g. VOC, CO2, germs).

Notes: No Abstracts.

Notes: No Abstracts.

Notes: Protoplasts of a xylose-fermenting yeast strain (a fusion product of Pachysolen tannophilus and Saccharomyces cerevisiae) were fused with isolated nuclei of the xylan degrading filamentous fungus Fusarium moniliforme. Polyethyleneglycol 4000 was used as the fusogenic agent. Fourteen stable hybrids showing xylanase activity were obtained. It can be assumed that this ability was acquired from the nuclear genome of the fungus, since the parental yeast strain did not show any xylanase activity. The enzymatic activity was determined quantitatively. The parental strain of the fungus reached its maximum xylanase activity of 796 nkat/ml at 96 h of growth. Four of the hybrids had a xylanase activity of between 211 and 297 nkat/l at 24 h of growth. Zymograms of these hybrids showed the presence of xylanases when grown on xylan as the sole carbon source. Using pulse field electrophoresis gels, no difference between the chromosome pattern of the fusion products and the parental yeast strain was observed.

Notes: No Abstracts.

Notes: The calluses of two hydroxyproline-resistant lines (D20-1 and D30-1) of Solanum tuberosum L. were transferred to a solidified MS medium containing 1.0 mg/I IAA, 2.0 mg/l zeatin, 40.0 mg/l adenine sulphate, 1 g/l casein hydrolysate, 20 g/l sucrose and 10 g/l agar for plant regeneration. The shoot regeneration was only achieved from the callus of line D20-1. Regenerated shoots exhibited morphological variability. The degrees of frost tolerance were higher in the leaves of the regenerated plants compared with the leaves of the non-selected control plants, but lower than that of the callus from which they were regenerated.

Notes: In situ hybridization with fluorescently monolabelled rRNA-targeted oligonucleotide probes (17 to 18 nucleotides) was used to discriminate between Alcaligenes eutrophus JMP 134 and Acinetobacter calcoaceticus 69-V by flow cytometry. The strains were grown in batch experiments in a mixed population. The forward light scatter and fluorescence of each bacterial cell were measured with a single laser cytometer. The intensity of fluorescence after rRNA staining depended on the content of ribosomes, which correlated with the growth rate of bacteria. Therefore exponentially growing cells could be clearly detected. For other growth phases, signal amplification was necessary using multiple probes. The two bacterial strains were identified with differently labelled probes under an epifluorescent microscope. Using a single laser cytometer, rRNA based identification was possible nut not ideal. Better discrimination between the two strains of the mixed population was achieved by DNA staining, combined with the different forward light scatter signals. Due to the significantly different cellular DNA and GC content of both strains, the fluorescent dye DAPI (4′, 6-diamidino-2-phenylindole), preferring AT-rich regions of DNA, was found to be a supplementary tool for population analysis. The abundance ratios of the two strains in mixed culture determined by DNA or rRNA staining were similar.

Notes: The process of leachate denitrification by populations of nitrifying and denitrifying bacteria was investigated. Leachate, derived from a local municipal landfill site, was nitrified in a continuously operating packed-bed biofilm reactor and thereafter denitrified in an activated sludge bioreactor. To follow the progress of nitrogen elimination, ammonium, nitrite and nitrate concentrations were determined at all stages of the process. While the nitrite and nitrate concentrations were measured by conventional colorimetric methods, computer controlled coulometric titration with in situ generated hypobromite was used for ammonium determination, which had previously been selectively separated from the sample matrix by gas dialysis. The detection range of the method was from 1 × 10-6 to 1 × 10-3 M ammonium (relative standard deviation (RSD) = 2%, n = 6). No interference of the complex sample matrix was found in ammonium determination. The average ammonium concentration in the leachate was 409 mg/l (standard deviation (SD) = 142 mg/l, n = 55). The ammonium concentrations decreased to 1-5 mg/l during nitrification under continuous operating conditions. Increased ammonium concentrations after nitrification correlated with a decrease in the efficiency of nitrogen elimination by up to 45% due to the build-up of high concentrations of nitrite. The concentration of sulphides, another source of pollution of the leachate, was also determined by triangle programmed coulometric titration. The average concentration of sulphides in the leachate was 221 mg/l (SD = 374 mg/l; n = 55). The sulphide concentrations decreased to concentrations below the detection limit of the coulometric titration (2 × 10-6M) during nitrification.

Notes: A new finite-state method is proposed which has been designed for use in biotechnological processes, in particular for the control of the pH in acidic waste water.The automation of expedient behaviour takes into account the non-linear character of the process and a good control stability in spite of variations in the influent acidic concentration, dissociation constant of the acid and change of the pH set point.To design the controller with the proposed method, no model of the process is required. Simulation studies show that expedient behaviour of an automaton in a random medium for the control of the pH neutralization process can give a good performance.

Notes: The potential for the production of 1,4-piperazinium-(L, L)-dilactate from L(+)-lactic acid preparations obtained by fermentation was studied. Piperazinium dilactate was found to be a very suitable source material for poly(lactic acid) production. In a novel polymerization process, the intermediate dilactide was directly formed in the salt melt at a moderate temperature. High-performance cultivation of Lactobacillus paracasei on a glucose-MRS medium was carried out using high-viability inocula. After the cell mass had been removed from the fermentation broth by centrifugation and/or ultrafiltration, the lactic acid solution was concentrated to 45% [w/w] by a two-stage electrodialysis process. Two methods of preparing 1,4-piperazinium dilactate were developed: the first from the medium-concentrated lactic acid (45%) and the second from a highly-concentrated lactic acid (85%) obtained by evaporation from the first one. Because there were no physical data on 1,4-piperazinium-(L, L)-dilactate in specialized literature, the pure product was characterized according to its solubility characteristics, melting point and spectroscopic analysis.

Notes: A total of 65 yeast strains were screened for their ability to grow and ferment lactose in a standard DURHAM tube test at 30 °C. Based on the kinetic parameters for lactose and whey lactose fermentations in shake flask cultures, the strain Candida psedotropicalis 65 was chosen for further studies.Some of the cultural parameters affecting ethanolic fermentations on lactose were standardized. At an initial lactose concentration of 100-120 g/l in the medium containing concentrated whey or lactose, at 40 °C and within 48 h, the selected strain reached an ethanol concentration of 41-59 g/l, an ethanol productivity of 1.3-3.0 g/l/h, a lactose consumption of 99%, an ethanol yield 0.4-0.49 g/g and a biomass yield of 0.027 g/g.

Notes: High temperature extrusion cooking of rye was used as a pretreatment for ethanol fermentation, and yeasts and bacteria were compared for their fermentation rates. Extrusion cooking caused, on average, a 7.5% increase in ethanol yield in comparison to autoclaved samples. The best results were achieved for grain with a moisture of 21-23% which was extruded at temperatures of 160-180 °C.Extrusion decreased the relative viscosity of rye grain water extracts, so it was possible to mash it without α-amylase. The efficiency of fermentation of extruded rye without Termamyl was equal to that of autoclaved and traditionally mashed rye (using α-amylase).The rate of fermentation of extruded rye grain by Zymomonas was higher during the first stage, but the final ethanol yield was similar for the bacterium and the yeast.Though both microorganisms gave good quality distillates, the concentration of compounds other than ethanol achieved from extruded rye mashes, which were fermented by Z. mobilis, was five times lower than for yeasts.

Notes: A poppy cell suspension culture was permeabilized by Tween 80 and immobilized by glutaraldehyde. The α-Galactosidase in these cells showed an optimum pH level at 5.2 and an optimum temperature at 70 °C. Enzyme hydrolysis was linear for 3 h, reaching 86% conversion. A very good level of storage stability was achieved when using dry catalyst and immobilized cells in 0.15 M NaCl solution (with the addition of chloramphenicol, [1-methyldodecy1)-dimethylamin-4-oxide (ATDNO), chlortetracycline hydrochloride (CLCTC)] or by freezing them in 0.15 M NaCl solution.

Notes: Cells of an Actinomycete-like bacterium, strain GJ70, with the ability to degrade several haloalkanes were used as a biological component in a discontinuous microbial bioassay for the detection of 1,3-dichloropropene and 1,2-dibromoethane in water. The cells were entrapped in different matrices such as calcium alginate, carrageenan, chitosan, polyacrylamide-hydrazide and chitosan-carboxy-methyl cellulose; the specific dehalogenating activity of the immobilized cells to a stirred sample solution and by the use of an ion selective electrode (ISE) for the quantification of enzymatically released halogen ions, the concentration of halogenated hydrocarbons could be estimated by determining the change of electrode potential within a period of 5 min. The detection limits for 1,3-dichloropropene and 1,2-dibromoethane were below 100 μg/l and 25 μg/l, respectively; the relative standard deviation was 〈 10%. In addition, several chlorinated and brominated hgydrocarbons were converted by the bacterial cells at a reduced rate e.g. 1, 2-dibromopropane, 1-bromoethane, 1,5-dichloropentane, etc. Moreover, temperatures of between 20 and 40%C did not affect the enzymatic activity of the cells, and a pH of between at 5 and 9 had little influence. Several organic substances and non-metabolizable compounds did not affect the conversion, whereas some heavy metal ions acted as inhibitors.

Notes: This review is concerned with the application of hairy roots, i.e. plant roots formed from plant cells after transformation by Agrobacterium rhizogenes for the production of bioactive compounds. Transformed root cultures have been established from numerous species of dicotyledonous plants. The plants, as well as the main products accumulated in hairy root cultures derived from these plants, are listed in this paper. Data are presented on novel compounds, hitherto detected only in transformed roots but not occurring in the corresponding intact plants.The possible use of hairy root cultures for the over-production of secondary metabolites and biotransformation of chemicals is discussed. In order to enhance the productivity of hairy root cultures, various methods have been derived, and optimized procedures are proposed. They include selection of high-producing clones, elicitation, composition of growth media, culture conditions and genetic approach. Hairy roots usually store secondary metabolites in vacuoles inside the cells. Therefore, several methods have been used to increase the amount of products released into the medium. Unfortunately, no general procedure is known that works in all cases, and the excretion behaviour of hairy root cultures varies from one species to another and even within one species from one clone to another.Special attention is given to the cultivation methods and bioreactor systems for hairy root cultures. Hairy roots are cultivated usually in shake flasks; however, shake flask culture is not suitable for the complex optimization and continuous control of the culture conditions. In this paper, we are going to present bioreactors proposed for the cultivation of hairy roots under more or less controlled conditions. Modifications of typical bacterial bioreactors, i.e. stirred tanks, airlift loop reactors and other constructions, are presented. A very special type of bioreactor providing good conditions for loose root mass multiplication without oxygen or substrate limitations, is the mist bioreactor. Nowadays, it is practically impossible to select the one best bioreactor type for hairy root culture.

Notes: Hydrolyses of olive oil were performed in a reactor with lipase immobilized on a laboratory ultrafiltration poliamide-6 membrane. The reactor consisted of two circulating phases of olive oil and buffer solution. For the characterization of the reactor performance, a model of the hydrolysis process was developed. It was created by means of thermodynamic network representation of both the chemical processes and the transport of the reactants. According to an estimated bond graph network, the model is represented quantatively by a set of thirty-three differential equations representing the time derivatives of the particular species concentration. The parameters of the model were estimated based on experimental data and/or literature notations. Close agreement of numerical estimations of the product concentrations with experimental data was gained. The model enabled an extended analysis of the influence of different reaction parameters, enzyme inhibition and concentration of the reactants on reactor performance.

Notes: The effects of anoxic conditions on product inhibition and the stability of L-ATC hydrolase were investigated in the conversion of D,L-2-amino-Δ2-thiazoline-4-carboxylic acid (D,L-ATC) to L-cystine using the cell free extract enzyme of Pseudomonas sp. in the presence of hydroxylamine. At L-cysteine equivalent levels, where one mole of L-cystine was counted as two moles of L-cysteine, L-cystine inhibited the L-ATC hydrolase reaction to a greater extent than L-cysteine. In air, the product occurred predominantly as L-cystine (94.9%), whereas in a nitrogen atmosphere the product occured as a mixture of L-cysteine (39.3%) and L-cystine (40.7%). As a result, less product inhibition took place in nitrogen. The activity of L-ATC hydrolase was almost fully lost after 20 h of incubation by shaking at 30 °C in air, but considerable activity remained under the anoxic conditions of nitrogen. A kinetic analysis of the reactions confirmed that reduced product inhibition and enhanced enzyme stability in nitrogen result in a more efficient enzyme reaction. The inactivation rate constant (k1) was estimated to be 0.11 h-1 in nitrogen and 0.22-1 in air, indicating that the stability of L-ATC hydrolase in nitrogen was greater than in air. The values of the Kp1 and Kp2 constants related to product inhibition were 43.36 mM and 30.48 mM for L-cysteine and L-cystine, respectively, where higher values were an indication of less product inhibition. The value of the rate constant (k2) for the oxidation of L-cysteine to L-cystine was 0.09 h-1 in nitrogen and 1.01 h-1 in air, suggesting that the oxidation of L-cysteine to L-cystine proceeds faster in air than in nitrogen.

Notes: R. opacus UFZ B 408 is able to use pyridine, a potentially growth-inhibiting substrate, as the sole source of carbon, energy and nitrogen. In a previous publication [1] we reported that with the simultaneous utilization of a second carbon and energy source in carbon-substrate-limited chemostat culture, stable steady states could be achieved at higher dilution rates than with growth on pyridine as the sole substrate. Owing to the higher growth yield during growth on such a substrate mixture, both the specific pyridine consumption rates and the residual pyridine concentrations were lower at similar dilution rates than with growth on pyridine alone. Therefore, the critical growth-inhibitory pyridine concentration was only achieved at a higher dilution rate.With the investigations presented here in carbon-substrate-limited continuous culture, the simultaneous utilization of pyridine and formate by R. opacus UFZ B 408 was studied. The yield coefficient during growth on pyridine as the sole substrate amounted to about 0.55 g dry mass/g pyridine. Theoretically, however, the carbon-metabolism-determined yield coefficient should have been about 0.915 g dry mass/g pyridine. Because of the difference between these two values the conclusion was drawn that pyridine is energetically deficient. That means that during growth on pyridine a part of the substrate was dissimilated to supply the energy required for the incorporation of the pyridine carbon into biomass. Formate cannot be used as a carbon source for growth by R. opacus UFZ B 408. However, with growth on pyridine, formate was oxidized simultaneously. During growth on pyridine/formate mixtures, the yield coefficient could be enhanced up to 0.7 g dry mass/g pyridine. That means that biologically usable energy, generated in the course of the formate oxidation, was used for the assimilation of pyridine carbon. The increase in the yield coefficient was related to the utilization ratio of formate to pyridine in a linear manner. However, the carbon-metabolism-determined yield coefficient of 0.915 g dry mass/g pyridine could not be achieved. That can be put down to the fact that R. opacus UFZ B 408 possesses only a limited capacity to oxidize externally supplied formate. Because of the limited formate oxidation capacity the probability is low that, with simultaneous utilization of formate, stable steady states could be achieved at substantially higher dilution rates than with growth on pyridine alone.Enzymatic studies revealed the induction of both NAD(P)+-linked glutaric dialdehyde dehydrogenase and isocitrate lyase during growth on pyridine. Therefore, the conclusion was drawn that pyridine is metabolized by R. opacus UFZ B 408 via the same pathway described for the utilization of pyridine by Nocardia Z1 [2]. This conclusion implies that the ability to oxidize formate represents a metabolic performance which seems not to be directly related to the pyridine metabolism of R. opacus UFZ B 408.

Notes: Enzymatic stereoselective hydrolysis of (R,S)-1-phenylethyl propionate was performed in a stirred tank and in a biphasic enzyme membrane reactor. Lipase from Pseudomonas sp. was proved to be a good enantioselective catalyst for this reaction. The enzyme was covalently immobilized in a porous polyamide membrane (flat sheet as well as hollow-fibres) via glutaraldehyde. An influence of membrane hydrophobicity on reactor performance was observed. Initial lipase activity and productivity in the processes were equal to 1.05 × 10-4, 1.3 × 10-5 and 1.0 × 10-5 mole/(h × mg of enzyme) in the case of native lipase, in the aromatic polyamide hydrophobic membrane reactor and in the hydrophilic polyamide-6 membrane reactor, respectively. The influence of some factors such as temperature, pH, buffer concentration, initial substrate concentration and addition of β-cyclodextrin derivatives on reaction rate and enantioselectivity was investigated and discussed. In the enzyme membrane reactor both organic and aqueous phases circulated countercurrently on both sides of the membrane. At a conversion degree of under 55-60%, pure enantiomer of the remaining ester (i.e. 〉 98%) was obtained.

Notes: Methylobacterium rhodesianum MB 126 was cultivated using extended cultures without outflow. The feeding regime was based on the pH-regulated synchronous dosages of ammonia, methanol, phosphatc and trace elements according to supposed stoichiometric relations. The acidity of the culture medium was kept constant at pH 6.8, whereas the dissolved oxygen concentration was adjusted at 80% of saturation by autoregulation of the stirrer speed. However, besides testing technical conditions, two types of fermentations were discovered which are described in this paper. Firstly, although at the beginning of the bioprocesses the impeller speed increased up to 2,000 rpm, a decrease of dissolved oxygen down to zero was unavoidable. Secondly, methanol was accumulated temporarily up to 44 g/l and 26 g/l at 23 h of fermentation time and without inhibition of growth at least up to 30 g/l or PHB production. During this accumulation of the carbon substrate, exponential growth phases were detected showing growth rates of μ = 0.20/h and 0.21/h. But then, phases of retarded growth followed, whereas the methanol disappeared either continuously or after a steady level. In the course of a 54-h fermentation period, the synthesized PHB amounted to a content of above 50% of cell dry mass. From this data, a volumetric productivity of 0.4 g PHB/lxh was estimated. Moreover, the growth related yield coefficients were calculated to YX/MeOH = 0.21 and YX/MeOH = 0.14, whereas the product related yield coefficients amounted to YPHB/MeOH = 0.12 and YPHB/MeOH = 0,09. Since the shift down of growth rates as well as the production of PHB agreed in time with partial oxygen limitation (40% oxygen saturation), the competition observed between the tricarboxylic acid cycle and PHB synthesis was discussed. Summarizing the results, it was concluded that the frequently described inhibitory effect of methanol of above 2 g/l seems to be rather an effect of experimentally chosen conditions than of a general physiological phenomenon. Therefore, it could be demonstrated that the toxicity of methanol could be overcome if it was not dosed at different times but simultaneously with other medium components.

Notes: A real-time artificial intelligence method for controlling the concentration of dissolved oxygen is proposed.Two projection versions of algorithms are considered in this paper. The versions vary in structure of the intelligent agents. One of the agents represents an automaton of expedient behaviour, the structure of the other consists of two automata which behave expediently in a complicated random medium.The first algorithm holds a check on a trend of change in values. The second version of the algorithm takes into account both the trend of change in the values and the speed of change in the values.Simulation studies show that expedient behaviour of the automata in the random medium for the control of dissolved oxygen concentration can bring about a good performance.

Notes: The production of L-glutamic acid with Corynebacterium glutamicum under biotin limitation was studied. Assuming a formal type of cell maturation, an adequate formal kinetic model was developed. This model includes growth, dependent on biotin, and uses the same retention term for describing the lag phase and cell maturation. Special attention was paid to the graphical interpretation of the performance between the variables, which is relevant for kinetics. Comparison between experiments and the model resulted in different degrees of agreement. However, the main trend of the experimental patterns of the complex bioprocess can clearly be mirrored in this model.

Notes: Bacterial strains have been isolated from contaminated concrete debris which exhibit the metabolic capability to degrade 2,4-chlorinated and 4-chloro-2-methyl-substituted phenols and phenoxyalkanoic acids including phenoxyacetate and phenoxypropionate derivatives. These strains were taxonomically identified. Two of them were found to belong to the β-subgroup of the proteobacteria and showed strong similarity to Rhodoferax fermentans. Preliminary investigations by PCR amplification using respective primers revealed that the strains harbour tfdA-like gene sequences.

Notes: The cell suspension culture Daucus carota L. was permeabilized by Tween 80 and immobilized by glutaraldehyde. β-Galactosidase showed an optimum pH of 4.7 and an optimum temperature of 55 °C. The enzyme hydrolysis was linear for 3 h, reaching a 65% conversion. A very good level of storage stability was achieved when using dry catalyst, or a solution of 0.15 M NaCl with the addition of chloramphenicol, (l-methyldodecyl)-dimethylamin-4-oxide (ATDNO), chlortetracycline hydrochloride (CLCTC) or by freezing the immobilized cells in 0.15 M NaCl. The cells characterized by high enzyme activity and stability in long-term storage showed convenient physicomechanical properties.

Notes: The enzyme Glucoamylase [1,4-α-D-glucan-glucohydrolase EC 3.2.1.3] is very important for the food industry. It is used for producing glucose, ethanol and beer, as well as in technological processes that require the decomposition of starch. Eight mutants of the species Aspergillus niger are evaluated and tested with respect to their production of Glucoamylase and proved to be suitable. The task is to find the mutant showing the highest enzyme activity with a given precision. Conventionally, this kind of multiple decision problem is handled by the analysis of variance (Model I), which tests the homogeneity of the population means, but in this case the results do not supply the desired information. Provided that the enzyme activities of the mutants are different, selection procedures can be used to choose the mutant with the “best” or at least a “good” level of activity.In this paper, a short methodical summary about the two classes of selection procedures is given, i.e. the indifference zone (and d-correct) procedures and the subset procedures. By the example of the selection of a mutant with high enzyme activity the planning of experiments is shown. Depending on suppositions about the variances, different selection rules are applied. Starting with the subset procedure of GUPTA, the number of mutants is reduced to seven. The following application of the d-correct procedures of BECHHOFER, DUNNETT and SOBEL allow us to calculate the necessary sample size of n = 49. Then the mutant whose sample has the largest mean will be selected as a “good” one with a given precision of d = 4 [u/l] and a probability of correct selection of (1-β) = 0.9This application is result of a cooperation between the Dept. of Food of the Technical University, Berlin, and the Dept. of Biotechnology of the Higher Institute of Food and Flavour Industry, Plovdiv, sponsored by the DAAD andthe TU Berlin.

Notes: Three different kinds of biomass, namely Populus deltoides, Eupatorium adenophorum and sericulture waste were used individually for the cultivation of Pleurotus sajor-caju, alone and mixed with paddy straw. P. sajor-caju, when used alone, exhibited a very good colonizing ability on these substrates, except in sericulture waste. The biological efficiency of P. deltoides and E. adenophorum when used as pure substrate was 75 and 77%, respectively, but it increased to 102% when P. sajor-caju was cultivated in a mixture with paddy straw in a ratio of 1:2. Experiments examining the growth on sericulture waste in both pure and mixed substrate are encouraging. From the analysis of substrate before and after the cultivation of P. sajor-caju it was noted that subsstrates were enriched in their protein content as a result of growth of this mushroom. The percentage of degradation of cellulose, hemicellulose and lignin showed that P. sajor-caju is capable of utilizing all three major components. The fruit bodies of P. sajor-caju were analyzed for crude protein content, crude fat and carbohydrate content. The energy values in the fruit bodies of P. sajor-caju and different organic wastes were found to vary from 282 to 309 kcal/100 g and from 319 to 467 kcal/100 g, respectively. It was found, however, that the energy recovery from organic wastes by fruit bodies was very low, i.e. 4.19-8.73 kcal/100g of dry substrate.

Notes: Forty-two white-rot fungi isolated in South America were incubated with long fibre sugar cane bagasse (LFB). The residual composition of LFB was determined after white-rot decay at 30 and 60 days. The ratio of residual lignin to residual lignin to residual cellulose (RL/RC) of untreated material (LFB) was 0.48. After white-rot-decay, the residual material with lower RL/RC ratios indicated that mainly lignin was degraded. In only 30 days, Phlebia sp. MVHC 5535, Athelia sp. MVHC 5509 and Spongipellis pachyodon MVHC 5019 caused a decrease in the RL/RC ratio to 0.36, 0.37 and 0.38, respectively, while it took 60 days for Ganoderma applanatum MVHC 5347, Hyphodontia sp. MVHC 5544, Panus tigrinus MVHC 5400, Stereum sp. MVHC 5113, Phellinus punctatus MVHC 5346 and MVHC 6388 to reach a ratio lower than 0.40. No correlation was found between the amount of some ligninolytic enzymes secreted and the residual composition of bagasse after white-rot fungi fermentation. Most of the fungal strains caused an increase in the relative amount of residual cellulose, indicating that hemicellulose was the preferred energy source.

Notes: An altered ploidy level was observed in plants regenerated by adventitious shoot formation from seedlings of Hypericum prformatum L. (2n = 4x = 32). Among the somaclones of the Ro generation, the presence of diploids (2n = 2x = 16), triraploids (2n = 3x = 24), tetraploids (2n = 4x = 32) and mixoploids was detected. Cytogenetic analyses of the R1 and R2 progenies showed that the chromosomal instability of the Ro somaclones was transferred onto the next generation.While almost all the seed progeny of diploids (100% in R1 and 94% in R2) progenies showed that the chromosomal instability of the Ro somaclones was transferred onto the next generations.While almost all the seed progeny of diploids (100% in R1 and 94% in R2) and more than 60% of tetraploids (61% in R1 and 73% in R2) retained their chromosome number, cytogenetic diversity was observed in the progeny of triploids, mixoploids and some tetraploids.Somaclones and their offspring were analyzed for hypericin content. Statistical evaluation showed a correlation between hypericin content and ploidy during a two-year cultivation of R0 somaclones and in their R1 and R2 progenies.

Notes: An enzymatic membrane for application in the processes of decomposition and removal of urea from aqueous solutions was prepared: jack bean urease was immobilized on an aminated polysulphone membrane by adsorption. The inhibition of the system by boric acid was studied using procedures based on the MICHAELIS-MENTEN integrated equation (non-linear regression, and the linear transformations of WALKER and SCHMIDT, JENNINGS and NIEMANN, and BOOMAN and NIEMANN). The reaction was carried out in a 100 mM phosphate buffer of pH 7.0, containing 2 mM EDTA, obtained by neutralization of orthophosphoric acid with NaOH, at an initial urea concentration of 10 mM, and a temperature of 25 °C. The reaction was initiated by the addition of the enzyme to the urea solution, and was monitored by removing samples of the reaction mixture for NH3 determinations by the phenol-hypochlorite method until the urea was exhausted. The results were compared with those obtained earlier under the same reaction conditions for free urease and urease covalently immobilized on chitosan. The inhibition was found to be competitive, similar to that of the free enzyme and urease immobilized on chitosan, with inhibition constants Ki equal to 0.36, 0.19 and 0.60 mM. The results show that adsorption of the enzyme on a polysulphone membrane changed the enzyme to a lesser degree than covalent immobilization of the enzyme on a chitosan membrane.

Notes: Investigations were conducted with the aim of producing extracellular lipase from Candida rugosa by solid-state fermentation (SSF), using coconut oil cake (COC) as a solid substrate. To optimize production, various modifications were made to enrich the substrate by supplementing it with mineral solution, different carbon sources and several inorganic as well as organic nitrogen sources. Among them, urea (1%), peptone (3%) and maltose (5%) were found to be most suitable. Addition of olive oil (10%) encouraged lipase synthesis. The maximum lipase activity in the enriched substrate was 87.76 units per gram of dry fermented substrate [U/gds] compared to 25.81 U/gds in the raw cake at 96 h of fermentation, and growth was as high as 14.44 mg/gds of glucosamine. This was reached at 72 h in the enriched substrate. C. rugosa growth was calculated indirectly by estimating the glucosamine content in the cell wall after its hydrolysis. The enzyme yield was far better than any values reported as yet.

Notes: In this work, an immobilization method for polymer-levan production by a non-flocculating Z mobilis culture was developed. The extent of cell attachment to the stainless steel wire surface, culture growth and product synthesis were described. It was established that during short-term passive immobilization of non-flocculation Z mobilis cells on a stainless steel wire surface, sufficient amounts of biomass for proper levan and ethano fermentation could not be obtained. Adherence of cells was improved by pressing the paste-like biomass within stainless steel spheres knitted from wire with subsequent dehydration. Biomass fixed in metal spheres was used for repeated batch fermentation of levan. The activation period of cells within wire spheres (WS) was 48 h in duration. During this time, cell growth stabilized at production levels of ethanol and levan of Qeth = 1.238 g/l × h and qeth = 0.47 g/l × h; Qeth = 0.526 g/l × h and qeth = 0.20 g/l × h. Five stable fermentation cycles were realized using one wire sphere inoculum, and maintaining a stable ratio of 2.4 of biomass suspended in the medium to biomass fixed in the sphere. Using fixed Z mobilis biomass in the WS, the total amount of inoculum could be reduced for batch fermentation. Large plaited wire spheres with biomass may have potential in fermentation in viscous systems, including levan production.

Notes: Urban waste waters were treated with pure ozone or combinations of ozone, hydrogen peroxide and/or UV radiation to study the course of resulting BOD (biological oxygen demand)-time profiles and to propose a kinetic model. BOD-time profiles of chemically treated waste waters show an initial lag period that first order kinetic models cannot describe. A second order kinetic model is then proposed that satisfactorily fits experimental BOD-time profiles, except when hydrogen peroxide has been used. In these cases, BOD-time profiles present the highest lag periods observed. By applying this model, three parameters are determined: the biokinetic constant (k) which is an index of the biological removal rate; the potential amount of biodegradable matter (BODT), and the measure of the size of inocula and microbial activities of microoganisms (λ). The model was checked with experimental results of BOD-time profiles corresponding to both untreated and chemically ozonated urban waste waters. Ozonated waste waters showed the highest values of k and BODT, which implies an improvement of waste water biodegradability after ozonation. However, values of λ corresponding to ozonated waste waters presented lower values than those of untreated waste waters. This was due to the lag period observed in the BOD-time profile, which was a consequence of a lack of microorganism acclimation to ozonated waste waters. The effect of the ozone does, pH and carbonates during ozonation on COD (chemical oxygen demand) and the above indicated parameters was also studied. There was an optimum ozone dose which was 138 mg/l for this specific system. This led to the highest biodegradable fraction (ϕ) and the highest biokinetic constant (39% increase in ϕ and 4.7- fold increase in the value of k, respectively, compared to untreated waste waters.). Another significant fact was that a higher COD reduction was observed in the absence of carbonate during ozonation at basic pH values. In addition, the percentage of variation in the biodegradable fraction (Δϕ) of ozonated waste water increased compared to the untreated waste water at acid pH. The results suggest that ozonolysis, the direct molecular ozone way of reaction, due to its selective character, increases the biodegradability of waste water more than other chemically advanced oxidation processes based on hydroxyl radical reactions.

Notes: Waste waters from olive oil processing may cause severe pollution in the Mediterranean area, since they have a high level of chemical oxygen demand (COD) (100-200 g/l) and contain other organic and inorganic compounds. In all olive oil producing countries, the reduction of pollution in olive oil mill waste waters at reasonable costs and using techniques suitable for most industrial applications is an unsolved problem.For this paper, the yeast Yarrowia lipolytica ATCC 20255 was grown on waste waters from an olive oil mill in a 3.5 1 fermenter under batch culture conditions.The results showed that the yeast was capable of reducing the COD value by 80% in 24 h. In this way, a useful biomass of 22.45 g/l as single cell protein (SCP) and enzyme lipase were produced.During this process, most of the organic and inorganic substances were consumed, only aromatic pollutants were still present in the fermentation effluents. Therefore, we used a phenol degrader, namely Pseudomonas putida, to reduce phenolic compounds in the fermentation effuents after removing Yarrowia lipolytica cells. P. putida was effective in reducing phenols in only 12 h.

Notes: Hydrolysis and transformation of Fibrenier cellulose (USA) with enzymes from Aspergillus niger IBT-90 was studied. The process was performed at 50°C and pH 4.8 for 24 h using an enzyme complex either as a properly diluted culture filtrate or as a mixture of isolated and purified enzymes from A.niger IBT-90. In the latter experiments, enzyme-substrate ratios expressed as units of activity per 1 g of cellulose were as follows: endoglucanase E1 and E2, 40; β-glucosidase, 40 and cellobio-hydrolase, 2. Cellulose concentration was 5%. It was proved that the crude celluloytic complex from A. niger IBT-90 exhibits higher efficiency in the decomposition of cellulose in comparison to the mixture of enzymes isolated from this complex, as was revealed in assays of reducing sugars and determinations of light transmission throughout cellulose fibres using a computer analysis of the microscopic image. Comparison of both the endoglucanases E1 and E2 showed that the first enzyme is more active against cellulose. It liberated more reducing sugars and caused more significant decomposition of fibres. The predominant effect of the endoglucanase E2 was a smoothing of the fibre surface. The cellobiohydrolase split a cellulose fibre into many short fibres.

Notes: Molecular evolution has recently been applied in biotechnology which consist of the development of evolutionary strategies in the design of biopolymers with predefined properties and functions. At the heart of this new technology are the in vitro replication and random synthesis of RNA or DNA molecules, producing large libraries of genotypes that are subjected to selection techniques following DARWIN's principle. By means of these evolutionary methods, RNA molecules were derived which specifically bind to predefined target molecules. Ribozymes with new catalytic functions were obtained as well as RNA molecules that are resistant to cleavage by specific RNases. In addition, the catalytic specificities of group I introns, a special class of ribozymes, were modified by variation and selection.Efficient applications of molecular evolution to problems in biotechnology require a fundamental and detailed understanding of the evolutionary process. Two basic questions are of primary importance: (i) How can evolutionary methods be successful as the numbers of possible genotypes are so large that the chance of obtaining a particular sequence by random processes is practically zero, and (ii) how can populations avoid being caught in evolutionary traps corresponding to local fitness optima? This review is therefore concerned with an abridged account of the theory of molecular evolution, as well as its application to biotechnology. We add a brief discussion of new techniques for the massively parallel handling and screening of very small probes as is required for the spatial separation and selection of genotypes. Finally, some imminent prospects concerning the evolutionary design of biopolymers are presented.

Notes: Toluene was anaerobically degraded by an enriched mixed culture under methanogenic conditions. The mixed culture was originally developed from cow-dung and sludge from a laboratory reactor, in which benzene was anerobically degraded by sulphate-reducing bacteria. First the mixed culture was enriched on toluene over a year with and without the use of sulphate in the medium. For the evaluation of growth-kinetic and maintenance parameters, namely μmax, Ks, kd and Yx/so, the anaerobic degradation of toluene was carried out in batch as well as in continous reactors systems. The gas volume and the methane content in the produced gas was somewhat lover than the theoretical value expected, indicating an incomplete degradation of some of the complex intermediates of the toluene degradation pathway. However, the mixed culture was able to transform 41.3% of the toluene carbon into methane.

Notes: The data presented here with respect to the behaviour of industrial scale stirred tank bioreactors equipped with modified RUSHTON turbine agitators in the biosynthesis processes of antibiotics are valid for that case that the power consumption is the same as it is in standard RUSHTON turbine agitators.Each modified RUSHTON turbine agitator was obtained through the variation of the blade surface by adding perforations so that the ratio between the perforation surface area and the full surface area (or the surface fraction of the perforations) is 0.36.In the fermentations of Streptomyces aureofaciens, Streptomyces rimosus and Penicillium chrysogenum producing tetracycline, oxytetracyline and penicillin, respectively, in bioreactors equipped with modified RUSHTON turbine agitators, the relative antibiotic production is increased by more than 30% compared to standard bioreactors.

Notes: No Abstracts.

Notes: No Abstracts.

Notes: No Abstracts.

Notes: No Abstracts.

Notes: No Abstracts.

Notes: In previous studies, the white-rot basidiomycete Lentinus edodes, strain SC-495, was proved to be a “selective” lignin degrader and its extracellular crude preparations arising from solid-state cultures were successfully employed in biopulping experiments on annual plants. This fungus produced extracellular laccase as the predominant phenoloxidase when growing in solid-state fermentation on corn stalks. Laccase from this strain was purified and partially characterized, as an initial approach towards the study of its ligninolytic complex. Laccase was purified 69.6-fold by anion-exchange chromatography and two affinity-chromatography steps with an overall yield of 7.45%. The native enzyme exhibited a molecular mass of 74 kDa, an isoelectric point of 3.42 and a carbohydrate content of 7.5%. The absorption spectrum of laccase showed a maximum at 605 nm, typical of blue-copper oxidases. The optimum pH and temperature for the activity of laccase were 4.0-4.2 and 50°C, respectively. Kinetic experiments, performed with a wide range of phenolic compounds, showed that the reaction rate and the substrate affinity greatly varied depending on the nature of substituents and their reciprocal positions on the aromatic ring. In particular, the enzyme showed high affinity to phenolic compounds bearing methoxyl or methyl groups, but no affinity to those bearing the nitro group directly attached to the benzene ring, nor to non-phenolic lignin-related compounds, such as trans-cinnamic acid or 3,4-dimethoxycinnamic acid. The huge differences in terms of reactivity of the enzyme towards phenolic compounds suggests that a preliminary systematic screening should be advisable when using laccase in effluent treatment applications.

Notes: Instead of yeast extracts, casein hydrolysates from several suppliers were added to culture media and analyzed with respect to their ability to stimulate β-galactosidase activity in Kluyveromyces bulgaricus cells. Four enzymatic casein hydrolysates caused a significantly higher stimulation of enzyme activity, while acid casein hydrolysates clearly reduced the enzyme activity. Enzymatic casein hydrolysates, inducing high and low lactase activity, were analyzed with respect to average peptide length (APL), vitamins (niacin, pathothenate) as well as free and bound amino acids. The molecular weights of these casein hydrolysates were estimated by gel filtration. No correlation was found between the degree of enzyme stimulation and the vitamin contents, the APL values and the free amino acid contents of the casein hydrolysates. Casein hydrolysates stimulating the lactase activity were less soluble in water and, in a gel filtration column, they showed three peaks with slightly lower molecular weights than the three peaks seen in hydrolysates which had no effect on activity. APL values of alcoholic precipitates of casein hydrolysates showed an inverse correlation to lactase activity. The molecular weights of alcoholic precipitates of lactase stimulating digests were also lower compared to non-stimulating ones. Alcoholic precipitates with lactase-stimulating activity were more hydrophilic, as was shown by a smaller proportion absorbed in a C18 column and by amino acid analysis. Our results sugest that alcoholic precipitates could probably be important in the lactase stimulation and their composition should be further investigated. The mechanism is nevertheless complex and may be caused by various simultaneous factors.

Notes: Following our investigations on citrinin production by Monascus ruber in a chemically defined medium, the kinetic behaviour of this toxin in the fermenter was studied with relation to production of pigments, biomass and nutrient consumption. Showing a secondary metabolite pattern, citrinin was produced when dμ/dt and dQs/dt were ≤ 0, while a high specific production rate of pigments occurred when dμ/dt and dQs/dt were 〉 0. No trophophase-idiophase transition was detected during the cuitivation, and the behaviour of pigment production was similar to that of a primary metabolite.

Notes: No Abstracts.

Notes: This study focuses on the growth of Zymomonas mobilis strain 113 S and its ethanol and levan production under the conditions of increasing sucrose medium osmolality caused by NaCl, KCl, sorbitol or maltose. The increase in medium osmolality (700-1,500 mosml/kg) was accompanied by the inhibition of growth (growth rate, biomass yield) and ethanol production (specific productivity and yield) In contrast, levan synthesis was less affected or even stimulated and, as a consequence, levan specific productivity was increased significantly. A decrease in the anabolic growth parameters correlated with a parallel inhibition of glucose-6-P dehydrogenase and alcohol dehydrogenase (isoenzyme ADH II) activities. A significant inverse linear relationship (r = - 0.932, 1 - P = 0.01) was observed between the values of the specific productivities of ethanol and levan. This relationship was confirmed independently by a controlled reduction of growth and ethanol productivity (3.75-4.75 mM sodiumbisulphite as an acceptor of acetaldehyde formed in the pyruvate decarboxylase reaction). As further support of this relationship, a significant inverse correlation was observed between levan specific productivity and ATP concentration in Zymomonas mobilis cells, most probably demonstrating that a reduced level of energetic metabolism is favourable for levan production.

Notes: The remediation of polluted soils by microbial communities is a complex process, characterized by many competitive and cooperative mutual relations between the individual organisms. For the overall characteristic of such processes, top-down systems analyses promise a better description for prognostic aims than bottom-up approaches.This is demonstrated using the EVOLON model to fit the cumulative O2 consumption data of a microbial ecosystem metabolizing diesel fuel in polluted soil. The EVOLON is a generic top-down model providing close approximation to the experimental data.The advantage of using this model instead of other similar models is demonstrated by a comparison of the deviations between model values and experimental data (residuals).

Notes: Waste water, derived from the reprocessing of used emulsions or suspensions, contains high concentrations of emulsified mineral oil and stabilizers, as well as different additives that are needed during the treatment process.Two stirred-tank reactors and two fixed-bed reactors were used to study the biodegradation of these waste-water compounds during two-stage biological treatment. The waste water was first proceesed in an activated sludge reactor to remove easily biodegradable substances. The effluent from the first stage was treated in three parallel operating reactors: an activated sludge tank containing different amounts of powdered activated carbon (PAC, between 0 and 2%), an upflow anaerobic fixed-bed reactor and an aerobic fixed-bed reactor (trickling filter). The results from the continuous treatment were compared with laboratory batch experiments.About 60% of the influent TOC was reduced by the first activated sludge treatment. The removal efficiency increased to about 70% by using a second activated sludge stage. This degradation was comparable to the maximum degree of degradation measured in laboratory batch experiments. PAC addition to the second activated sludge tank resulted in increased degradation rates. The removal efficiency increased to about 76% when 0.1% PAC was added and to 96% with 1% PAC. The removal efficiency decreased to 84% when the proportion of PAC was further increased to 2%. Variations in the amount of PAC addition per unit influent volume in the range of 50 and 200 mg/l had no significant effect on the TOC removal.Degradation models based on the MONOD-type equation were found to be in close correlation with the results obtained from batch experiments. However, the biological removal rates measured in batch experiments did not reflect the removal capacity determined in continuous operating treatment systems.

Notes: A mathematical model has been developed to describe the stability behaviour of the pBR322 plasmid derivative pBB210 with the β-lactamase gene and the human interferon-α1 gene in Escherichia coli TG1 under non-selective, selective and modified selective conditions in a chemostat. The model was formulated on the basis of experimental investigations. It includes the interaction between β-lactam antibiotics (ampicillin and sulbactam) and cells (with and without plasmids), in particular the correlation between the growth rate of plasmid-free cells and ampicillin concentration in the medium; ampicillin transport into the periplasm of the plasmid-bearing cells; ampicillin degradation in the periplasm by by plasmid-encoded β-lactamase and the inhibition of the latter by sulbactam.The results obtained by the simulation of chemostat cultivations under various conditions and by steady state analyses are closely related to the results of experiments. Under non-selective conditions, the fraction of plasmid-bearing cells was approaching zero. Under selective and modified selective conditions, a coexistence between plasmid-free and plasmid-bearing cells was reached at steady state. Under these conditions, the steady state fraction of plasmid-bearing cells was proportional to the ampicillin concentration in the feed and inversely proportional to the cell concentration in the chemostat. During high-density cultivation, a large amount of ampicillin is necessary to suppress plasmid-free cells. Even small concentrations of the β-lactamase inhibitor sulbactam in the feed increased the steady state fraction of plasmid-bearing cells (from 17.2% to 99.6% at sulbactam-Na concentrations of 0 to 5 mg/l).

Notes: The growth of a thermophilic Clostridium sp. and the production of α-glucosidase, α-amylase and pullulanase were studied under anaerobic conditions using different carbon and nitrogen sources and varying pH values and temperatures. Growth and enzyme activities were highest with soybean meal as the nitrogen source. The optimum concentration was 2.5% [w/v] for the production of α-amylase as well as pullulanase and 2% [w/v] for α-glucosidase. The best carbon source proved to be soluble starch for α-amylase, and pullulanase and maltose for α-glucosidase. Growth and enzyme production reached their optimum at pH 6.5 to 7.0 and 70°C. Under these conditions, the enzyme activities followed exponential growth with maximum yields of α-glucosidase, α-amylase and pullulanase at 28, 36, and 44 h.

Notes: No Abstracts.

Notes: Pilot plant studies were performed using a concentric-tube airlift bioreactor of 2.5 m3 fermentation volume. The results have proven the relative merits of such a system in the biosynthesis of nystatin, produced by Streptomyces noursei, in submerged aerobic cultivation and batch operation mode. The results were compared to those obtained in a pilot-scale stirred tank bioreactor of 3.5 m3 fermentation volume.The fermentation processes in the two fermentation devices were similar with respect to substrate utilization, biomass production and nystatin biosynthesis.In the riser section, the dissolved oxygen concentration was higher than that in the downcomer.The volumetric oxygen mass transfer coefficient was dependent on the rheological behaviour of the biosynthesis liquids, which was not constant during the fermentation process.The total energy consumption for nystatin production in the airlift bioreactor was 56% of that in the stirred tank, while the operating costs represented 78% of those in the stirred tank bioreactor.

Notes: No Abstracts.

Notes: No Abstracts.

Notes: No Abstracts.