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Notizen: The mechanism of catabolic repression is not yet fully understood. Oxygen seems to control the level of cytochrome in the in situ state. The level of glucose seems to control other enzymes; glucose by itself does not repress the cataboism. An unidentified product of glucose metabolism is believed to be involved. In bacterial cultures, there is convincing evidence that cyclic AMP is involved and this operates at the levels of gene trancription. In yeast, it is not clear. The level of CAMP is found to be reduced with catabolic repressed cells, but there is little evidence to conclude that CAMP acts at the transcription level [1]. There are results to indicate that it acts at the translational level or enzyme activation phase in yeast. In order to understand this mechanism, the bioenegetics of yeasts grown under catabolic repression is analyzed with the data available [2] and appended.

Notizen: Cell disruption studies for the extraction of HBsAg from a recombinant P. pastoris strain (r-HBsAg) were done using a bead mill disintegrator. Three sequential passages (4 min retention time each) were enough to disrupt the cells and extract most of the r-HBsAg and soluble proteins. An acid precipitation step was performed just after cell disruption to precipitate proteins together with the cell debris. Different precipitation pH values (2.5 to 6.0) were investigated. A pH value of 4.2 was selected as a compromise between recovery and improvement of specific activity. A 6 to 8-fold enhancement of the specific activity was obtained, having a r-HBsAg overall yield of about 80%. The influencing presence of a chaotropic salt (potassium thiocyanate) during the acid precipitation step was also studied.

Notizen: For the immobilization of spores of Penicillium raistrickii i 477 the formation of polyelectrolyte complexes using the sodium salt of cellulose sulphate as polyanion and poly-dimethyl-diallylammoniumchloride as polycation was used. Light and scanning electron microscopy have shown that during germination of spores the capsule walls do not cause effective limitations on hyphal growth and that there are no significant morphological changes of the mycelium detectable by an outgrowth of immobilized spores. By comparing the 15α-hydroxylation of 13-ethyl-gon-4-en-3,17-dione with free and encapsulated cells it was found that an increase of total dry biomass per immobilized system led to a higher product formation in relation to free cells.

Notizen: The kinetics of batch fermentation during the growth of S. cerevisiae ATCC 36859 was studied in various glucose/fructose mixtures. It was found that the growth is inhibited equally by glucose and fructose even though fructose is not consumed to any large extent by the yeast under the conditions tested here. The inhibition of growth by the substrate and ethanol is represented by linear equations. These equations were combined with the MONOD expression in order to formulate equations for the biomass growth, glucose and fructose consumption and ethanol production. Parameter estimates were obtained by fitting these equations to batch fermentation data and so developing models which indicate that the growth is completely inhibited when 62 g/l ethanol is produced by the yeast, while glucose consumption and ethanol production continue up to an ethanol concentration of 152 g/l. Products containing a high concentration of fructose are best produced by using a high initial biomass concentration.

Notizen: Optimization studies have been carried out for the production of L-lactic acid from the fermentation of whey by Lactobacillus casei. Two Statistical Designs, a full 24 Factorial Design and a full 32 Factorial Design, have been used to determine the most suitable values of the operational variables for obtaining the maximum lactic acid production rate. The variables selected for study were temperature, pH, lactose concentration, and inoculum concentration. Among them only temperature and pH were found to affect the response significantly. A second-order polynomial empirical model relating both the response (lactic acid production rate) and the variables was formulated. The maximum acid production rate was found when the values of pH and temperature were 5.4 and 38°C, respectively. All conclusions are restricted to the experimental range studied.

Notizen: The influence of different process kinetics on the course of phenol degradation has been studied as well as the influence of axial dispersion in the liquid phase on the reactor height with relatively large biofilm thickness in a conventional fluidized bed and air-lift bioreactor. The object of this was to achieve a high conversion of substrate in a device of real size in real process time. For calculating the mathematical model, the method of orthogonal collocation with the STIFF integration routine has been used.

Notizen: The killing/immunity interactions among killer strains of the genera Kluyveromyces, Hansenula and Saccharomyces from the Czechoslovak Collection of Yeasts were studied with the aim to find the strains with broad specificity and killer activity targeted against a range of undesirable wild yeasts causing stuck fermentations. Among 49 tested Kluyveromyces strains, five strains were found, and among 55 Hansenula strains, ten yeast strains were found with activity against a sensitive strain of Saccharomyces. Hansenula mrakii CCY 38-7-1 and Hansenula saturnus var. subsufficiens CCY 38-4-2 showed exceptional activity against the wine contaminants, Zygosaccharomyces bailii, as well as against pathogenic Candida species within a broad range of pH 2.9-5.1. Their potential biotechnological application is discussed.

Notizen: α-Galactosidase (E.C.3.2.1.22) from Penicillium janthinellum was purified by precipitation and fractionation with ammonium sulphate, cold acetone or ethanol, calcium phosphate gel, and column chromatographies on Sephadex G-100 and G-200. The enzyme was purified about 110.39-fold when Sephadex G-100 was used. α-Galactosidase exhibited the optimum pH and temperature at 4.5 and 60°C, respectively. The optimum enzyme stability was obtained at pH 3.5 for 24 h (at room temperature). The enzyme was found to be thermostable below 65°C up to 40 minutes and was gradually inactivated by increasing the temperature above this degree. The MICHAELIS constant was 0.55 mM for p-nitrophenyl-α-D-galactoside. The α-galactosidase activity was strongly inhibited by Hg++ and slightly activated by Mn++. The results show the possibility of producing a thermostable enzyme from a low-priced agricultural product, for instance, lupine.

Notizen: The cultivation of Acetobacter methanolicus on various substrates revealed that the respective maximum growth rates are obtained at an almost identical oxidative capacity of about 16 mmoles of oxygen g (biomass)-1·h-1 under conditions of energy generations by complete substrate oxidation. This is considered to be an indication that the energy production rate determined by the capacity of the respiratory chain limits the growth rate in this strain. However, with glucose and glycerol, for example, a further increase in the growth rate is observed accompanied by the generation of products (gluconic acid or dihydroxyacetone, respectively). The incomplete oxidation should play the role of an additional energy generation. The potential for this rate increase is looked for in a higher energy gain derived from reduction equivalents (PQQH2) in this periplasmic oxidation step in relation to the cytoplasmic reduction equivalents.

Notizen: In this paper, we consider a model for a chemostat in which two microbial species compete for a single rate-limiting nutrient, while one of the species feeds on another. Under certain simplifying hypotheses, such a chemostat can be described by a system of three nonlinear ordinary differential equations. A theoretical study is conducted to characterize the possible types of solutions. A limit cycle solution was obtained for some parametric values of the system indicating that coexistence of the two species is possible in a significant range of the operating parameters.

Notizen: Pretreated wheat straw was enzymatically hydrolyzed in 250-ml flasks using the culture filtrate of Trichoderma reesei QM-9414. The influence of the initial enzymatic activity in the liquid phase was studied. The unreacted core model was used to analyze the experimental data obtained at 40, 46 and 50°C. The model adequately describes the data for hydrolysis times lower than 10 h.

Notizen: This paper intends to focus the attention to characteristic features of microbial lignin degradation from the phenomenological point of view. Six fundamental principles are discussed under special consideration of white-rot fungi. The necessity of mycelial growth and the formation, secretion, and extracellular action of peroxidases are main requirements for a successful microbial attack on polymeric lignin.

Notizen: The ligninolytic fungus Phlebia radiata growing in a low-nitrogen medium with Avicel cellulose as the sole carbon source produced a full spectrum of celluloytic enzymes. Some properties of these enzymes were investigated during the growth of the fungal culture.

Notizen: The ligninolytic fungus Phlebia radiata growing in a low-nitrogen medium, with wheat bran as the sole carbon source, produces a wide spectrum of hemicellulolytic enzymes. During the growth of the fungal culture, some properties of these enzymes were investigated.

Notizen: The synthesis of extracellular serine proteinase of Lactococcus lactis was studied during the growth in a batch and a continuous culture on chemically defined media. In a batch culture the proteinase synthesis started during the exponential phase of growth and the highest proteinase concentrations were found at the end of the exponential and beginning of the stationary phase of growth. During the growth in a lactose-limited chemostat with amino acids as the sole source of nitrogen, the specific rate of proteinase synthesis was maximal at a μof 0.23 h-1. At higher growth rates the proteinase productin declined. The proteinase synthesis was dependent on the amino acid sources in the medium. In batch cultures of L. lactis grown on a chemically defined medium with amino acids, the proteinase production was increased four-fold compared to media containing casein or a tryptic digest of casein as the sole source of nitrogen. The inhibition of the rate of proteinase synthesis by casein and peptides was also observed during the growth in a chemostat. The addition of the dipeptide leucylproline (final concentration of 100 μM) to a lactose-limited continuous culture during the steady state (D = 0.23 h-1) resulted in a transient inhibition of the rate of proteinase synthesis. This suggested that exogenously supplied peptides control the regulation of proteinase synthesis of L. lactis.

Notizen: 515 microorganisms of the genus Bacillus which produce starch-degrading enzymes were isolated from natural environments in the course of a screening programme. Treating the Bacillus strains on agar plates with iodine reagent for 30 seconds led to the selection of clones with increased amylolytic activity. This methods is very convenient for the screening of large numbers of amylolytic strains.

Notizen: Presently, an urgent problem is the application of artificial intellect (AI) methods as a complex way of controlling and optimizing technological processes. The paper presents major principles of a bystage application of AI in biotechnology as knowledge extraction from data obtained by decomposing the sign space to clusters.

Notizen: In biotechnological processes, fundamental performances of microorganisms are used. The economy of these processes is essentially determined by the efficiency, velocity (productivity) and quality of the products. Therefore it is a permanent task and challenge for basic and biotechnological research to seek out measures for improving the actually attained parameters. The auxiliary substrate concept supplics an approach. It is based on the fact that chemo-organo-heterotrophic substrates differ in the carbon: energy ratio, thus, growth yield is limited in energy and/or reducing power. It says that, by simultaneous utilization of physiologically similar substrates (mixed substrates), the growth yield increases. The substrates are to combine in such a way that with their simultaneous utilization a minimum of carbon is dissimilated merely for the purpose of the generation of biologically useful energy and/or reducing power. Since all chemo-organo-heterotrophic substrates are more or less energy-deficient, an increase in growth efficiency can be expected if the individual substrates of the mixture are assimilated more efficiently than the respective substrates alone. This may result, for instance, from an immediate assimilation of a substrate (according to the “manner of finished part construction”).An increased growth rate is rather the rule than the exception in mixed substrate utilization.In product syntheses the substrates are, depending on the concrete product and metabolic pathway, either energy-excess or energy-excess or energy-deficient. or, in other words, the processes are energy-generating or energy-consuming, respectively. If this is responsible for discrepancies between the possible yields determined by the carbon metabolism and the experimentally obtained yields, the discrepancies should be able to be decreased and the yields increased by mixing substrates. The substrates are to choose and combine so that, due to simultaneous utilization, the product formation process becomes energy neutral.As a rule, the enhanced efficiency is accompanied by an increased velocity. This does not only apply to syntheses, but also to degradation (and detoxification) reactions. Even supposedly inert compounds or persistent substances can be activated by simultaneous (co-)metabolization of another (an auxiliary substrate, victim substrate or co-substrate) and converted at a considerable rate. It is of interest for syntheses of products but in particular for degradation and decontamination of harmful and waste products in the environment that the residual concentrations of the substrates are smaller than those achieved if the compounds of a mixture are metabolized separately.The auxiliary substrate concept has proven to be fruitful, both for theoretical and practical questions. It was practically already being used before it was formulated (mixed substrate utilization, cometabolism). However, an abundance of regulatory and energetic aspects are waiting to be investigated in more detail.

Notizen: The basic parameters were studied influencing the conversion of orbitol to sorbose by Gluconobacter oxydans(industrial strain from FARMAKON Co., Czechoslovakia). The most effective conversion in the stationary phase was reached at pH 5.0, no inhibitory effect of sorbitol in a concentration ranging from 20 to 200 g/l and a minimum inhibitory effect of the sorbose concentration up to 200 g/l were observed. According to the optimum conditions mentioned above the optimized course of the fed-batch cultivation was proposed. The final concentration of sorbose of 410 g/l was reached after 36 hours.

Notizen: The optimization task was performed using the gluconic acid synthesis by the Acetobacter methanolicusMB 58 strain. The microorganisms were grown continuously on methanol as the growth substrate. After finishing the growth process by the deficiency of N and P, the gluconic acid synthesis was started by adding glucose. The synthesis process was performed continuously. The oxygen transfer rate depended on the gluconic acid concentration. During the growth process, the oxygen transfer rate reached a value of about 13 g O2 · kg-1 · h-1using a 30-l glass fermenter equipped with a 6 blade stirrer and fully baffled. This rate declined to a value of between 2 and 5 g O2 · kg-1 · h-1 in the presence of gluconic acid concentrations above 150 g gluconic acid · kg-1medium. The yield (g gluconic acid · g-1glucose) depended on the gluconic acid concentration and amounted to y = 0.7 in relation to 150 g gluconic acid · kg-1medium and y = 0.8 in relation to 200 g · kg-1medium, respectively. The fermenters were coupled with ultrafiltration moduls (Fa. ROMICON and Fa. SARTORIUS). The biomass concentrations amounted from 5 to 40 g dry mass kg-1medium. The ultrafiltration modules retained the biomass within the fermentation system. A glucose solution (30 to 50 weight percent glucose) was continuously dosed into the fermenter. The retention time was chosen between 2 and 30 h. The gluconic acid synthesis rate reached values of up to 32 g gluconic acid · kg-1 · h-1. Within a range of up to 250 g gluconic acid · kg-1medium, the acid concentration had no influence on the enzyme activity.

Notizen: Cylinder-shaped sintered glass carriers were successfully used for immobilizing and cultivating cells of murine line L929. The process has been performed in a fixed-bed bioreactor (working volume of 150 ml) with perfusion and aeration of the medium (total volume of 3.5 l). The maximum cell density of 1.23 × 107cells/ml was achieved when the basal medium (MEM + 10% bovine serum) was enriched with glucose (up to 2 g/l) and L-glutamine (up to 4 mM). The carriers have proved to be nontoxic, mechanically stable and reusable.

Notizen: In order to optimize the thermophilic lactic acid fermentation on saccharose as the sole carbon source and improve the effectiveness of the process, alternative nitrogen sources were tested and a minimal broth composition was found. Of the alternative nitrogen sources, whey protein hydrolyzate (WPH) was the best; the broth composition was reduced from seven down to three items. Application of ammonium as a neutralizing agent instead of sodium hydroxide brought an important positive change.

Notizen: Dual or multiple parameter flow cytometric analysis is developing into a powerful method for characterizing microbial populations. The distinguishing of the populations only by assignment of size/shape measurements by scattered ligth renders as not satisfactory.To differentiate between the cells, the employment of a specific fluorescence marker is absolutely necessary. Methods are presented for the flow cytometric determination of DNA and the polymer poly-β-hydroxybutyrate (PHB) content in three different bacterial strains. The measurement of the 3β-hydroxysterol content enables the differentation between yeast and bacterial organisms in mixed microbial populations. Monitoring the ratio of live to dead bacterial cells in soil or water samples, e.g. in pure culture systems, is shown.

Notizen: The growth rate and the maximum cell concentration of methanotrophic bacteria are limited by the transfer of methane and oxygen to the culture fluid. The operation under moderate pressure results in an increase in driving force for the mass transfer of both nutrients and, therefore, in a large increase in the attainable biomass concentration.Our laboratory pressure fermenter with a volume of 12 litres operates under a system pressure of up to 0.5 MPa. In this reactor a maximum productivity of 6 g biomass/lh is achieved. However, operating under moderate system pressure and exhaust gas recycling has also disadvantages because the concentrations of the gas phase components may inhibit the growth process.From the results of the laboratory fermenter we have developed kinetic models of the influence of dissolved oxygen and carbon dioxide on the specific growth rate of the methanotrophic strain GB 25. These models are the basis for processing under increased system pressure and exhaust gas recycling.

Notizen: A spontaneous association of Cellulomomas sp. with another bacterial strain was studied for its capabilities for single cell protein (SCP) production from bagasse pith. The associated strain was identified as Pseudomonas sp. and further characterized for its physiological properties. The effect of the initial proportions of both strains, the way of propagation, and the effect of pH on the growth of the mixed culture on bagasse pith was studied. Separate propagation of both strains before the fermentation step (“controlled mixed culture”), a range of proportions Cellulomonas-Pseudomonas from 4:1 to 100: 1, and pH 7.0, were found to be the most appropriate conditions of growth. A mutualistic symbiotic relationship was demonstrated to take place between both strains during the mixed growth on bagasse pith, the Cellulomonas supplying the carbon source (glucose produced from bagasse degradation) to the Pseudomonas, and the latter producing the vitamin supplements necessary for the Cellulomonas growth, allowing the growth of the mixed culture in a minimal medium, without any growth factor supplement. Fed-batch cultivation of the mixed culture on this substrate was successful, giving rise to high biomass production (19.4 g/l), thus increasing the productivity of the system. Due to its improved productivity, high biomass production, inexpensiveness of the culture medium, (without any vitamin supplement), and good stability, this culture presents economical advantages and constitutes an attractive choice for lignocellulosic substrate utilization.

Notizen: A mathematical model, DH = 1/k(10-2ΔpH - 1), between the pH-drop (ΔpH) and degree of hydrolysis (DH) of an enzymatic modification of casein was developed to assess the DH in a packed-bed column reactor by directly monitoring the pH value of the modified protein system. It was demonstrated that the linear DH range and the k value of the equation were dependent on the reactor type and the specificity of the proteolytic enzymes immobilized on chitin used in the present study, but no effect of the substrate casein concentration on the linear DH range was observed. Since DH and ΔpH values of the modified casein correlated with the flow rate in a packed-bed column reactor, it was suggested that the DH value, in a considerably wide range of casein modification with a certain immobilized protease in a column reactor, could be controlled by adjusting the flow rate of the substrate and monitored by a pH-meter. This relationship might be used as a basis for scale-up and long-term operation of enzymatic modification of proteins by immobilized protease in a column reactor.

Notizen: The expression of the human Growth Hormone (hGH) in transgenic mice is accompanied by health afflictions and structural changes in several organs and tissues. A macroscopic and light microscopic study was conducted to examine the morphological alterations related to the exposure of endogenously expressed hGH. Although many transgenic mice were under cachectic status, their body and organ weights were significantly higher than those of the controls matched. Kidney, liver and female genital organs were massively damaged.The most common findings in these organs were glomeruli hyalinosis and glomerulosclerosis in the kidneys accompanied by a varying degree of segmental sclerosis and necrosis. Tubuli dilatation was observed with hyaline casts and atrophied epithelium as well as interstitial fibrosis with mononuclear infiltrate. In the liver the hepatocytes were pleomorphic and exhibited vacuolar degeneration. Intranuclear lipid droplets were also found. Individual necrosis, mononuclear infiltrate and nuclear pseudoinclusions were also detected. The uterus exhibited cystic glandular hyperplasia and ovaries were observed to have several, large foamy cells as well as stromal infiltration of adipose cells. Other changes were found in the heart, the spleen and the salivary glands. A possible role of GH and/or the Insulin-like Growth Factor-I is suggested according to the morphological changes found. The similarity to kidney changes with human diabetic glomerulosclerosis was noticed.

Notizen: The tissue specificity of the expression of the hepatitis B surface antigen (HBsAg) in transgenic mice was studied. Northern blot hybridization and electron microscopy of various tissues revealed the higher HBsAg transcription levels confined to the liver and kidney, and to a lesser extent to the spleen and intestines. In electron microscopic studies we found HBsAg particles in the serum of transgenic animals to be positive by ELISA to HBsAg. The expression of the transgene was localized in situ in the ovary, liver, kidney, and spleen of transgenic mice, employing a polyclonal antiserum directed against the HBsAg and conjugated with protein A-gold. Surprisingly, F1 transgenic females from the CB-104 line, expressing HBsAg in the serum, showed impaired fertility, although the ovarian function was not diminished. Normal off-spring were obtained after cross embryo transfer between transgenic (Tg) females to non-transgenic (Ntg) recipients or from Ntg embryos transferred to Tg recipients. We speculate that this phenomenon could be related to a disruption on a gene(s) somehow involved in the reproductive performance of the transgenic females.

Notizen: Fifteen trace elements have been tested to determine the requirements for the growth of Phellinus pachypholeus Pat. The fungus requires in ppm, Fe: 10, Zn: 10-100, Mn: 1.0, Cu: 1.0, Mo: 1.0, B: 10.0-100. It does not require Ca, Pb, Br, I, Cr, Hg, W, Li or Cd. Concentrations higher than the optimum were progressively inhibitory for its growth.

Notizen: Process control strategies, e.g. the steady-;state fermation, which do not consider the cell-;state distribution of cell populations, cause a decrease of yield coefficient connected to an increase of heat-;production coefficient.Contrary to this, the dynamic process control adapts the carbon-;substrate supply to the different repetitive cell-;population states during fermentation. In order to recognize the different states, the cell population is synchronized. The optimum period ofchanging carbon-;substrate supply was found to be dependent on the cell-;doubling time. Dynamic process control causes a higher yield coefficient as well as a lower heat-;production coefficient compared to the steady-;state fermentation.

Notizen: Phanerochaete chrysosporium cells were immobilized on the sintered porous glass support. Such a biocatalizer was used as a bed of the enzymatic reactor system for the continuous production of lignin peroxidase. From the after culture fluid the lignin peroxidase enzymatic activity was recovered and purified applying anion exchangers. Additionally, some physico-chemical properties of lignin peroxidases were determined.

Notizen: It has been found visually and by spectrophotometric measurements that the infection of the algae culture of Sc. acuminatus used for biomass production has caused a changing of its color toward the large wavelengths of the spectrum. Experimental studies have proved that the color change was due to the reaction between the phytoplankton and the nitrous acid produced throughout the cultivation process. It has also been demonstrated that the coefficient of bathochromicy introduced in this study was efficient for quantitative estimation of algae biomass color, and could be used for control of algae culture color.

Notizen: The best yields and productivities of 0.38 g · g-1 and 0.35 g · l-1 h-1, respectively, for the propionic acid production in a batchsystem using sugar-cane final molasses as carbon source were obtained when an initial TRS concentration of 50 g · l-1 was used.It was obvious that this process is severely inhibited by the acids produced and the most drastic effect (μ = 0) was at a TVA concentration near to 250 mmol · l-1, independently of the initial TRS concentration employed.A generalizated equation of noncompetitive inhibition was adjusted: \documentclass{article}\pagestyle{empty}\begin{document}$$\mu = \frac{{\mu _{\max } }}{{1 + \left( {\frac{{TVA}}{{K_{\rm P} }}} \right)^n }}$$\end{document} and kinetic inhibition constants for each initial TRS concentration studied were estimated.

Notizen: The mechanical disrupture is described with the examples of selected yeasts, fungi and bacteria under practical circumstances. A particularly high degree of disrupture while simultaneously avoiding a strong destruction of the cell wall, and a trouble-free continuous are operation are considered.With the aid of laboratory studies and the physicochemical data of the biomass, suitable equipment for the small technical and industrial scale can be chosen.

Notizen: A fed-batch process is used for the production of concentrated pure fructose syrup and ethanol from various glucose/fructose mixtures by S. cerevisiae ATCC 36859. Applying this technique, glucose-free fructose syrups with over 250 g/l of this sugar were obtained using High Fructose Corn Syrup and hydrolyzed Jerusalem artichoke juice. By encouraging ethanol evaporation from the reactor and condensing it, a separate ethanol product with a concentration of up to 350 g/l was also produced. The rates of glucose consumption and ethanol production were higher than in classical batch ethanol fermentation processes.

Notizen: The feasibility of using ultrafiltration to concentrate RNA was investigated. Ultrafiltration flux and solute retentivity were affected by membrane cut-off and inlet pressure.The RNA can be concentrated by selecting a hydraulically permeable membrane (PM 30) and then operating the system at a sufficiently high pressure (2.07 · 105 Nm-2) and a high recirculation rate (150 cm-1). The use of this procedure was limited to a high-flux regime. However, a very high retentivity of macrosolute was achieved. The effect of transmembrane pressure on the apparent mass transfer coefficient in the “gel polarization model” was discussed and related to ultrafiltration flux.

Notizen: Some special features of the fluidization technique, such as very good mixing behaviour, small-scale abrasive and thermical stress, permit an advantageous utilization in bioengineering. The use of the fluidization technique for fermentation, immobilization and working up and conditioning is investigated. Existing results with regard to using gas-fluidized beds in bioengineering are promising and have been investigated further.

Notizen: Two methane utilizing bacteria strains, GB 21 and WSB 874, were cultivated with methane as sole carbon and energy source in a submerged continuous fermentation process. The aim of the investigations was to reach high biomass concentrations (〉25 g BDM ·kg-1 medium) and high productivities (〉3 g BDM · kg-1 · h-1). A precondition for the high-performance fermentation process was to ensure a transfer rate of methane and oxygen in quantities required by the microorganisms. For this purposes a high performance stirred pressure fermenter was used. The fermentation process is characterized by the transfer of two gaseous substrates. In order to develop a technical process it was necessary to investigate both the correlations between the two gases and the productivity of the fermentation process and the influence of system pressure on the microorganisms.Within a pressure range of up to 0.7 MPa a biomass concentration of up to 50 g BDM · kg-1 medium and a productivity of up to 9 g BDM · kg-1 · h-1 was reached in a continuously running fermentation process under nonsterile conditions. Under these fermentation conditions the microbial population consisted of a dominating main culture GB 21 or WSB 874, respectively, and an accompanying flora (type II). The microbial population was very stable in its composition during the fermentation process running continuously for weeks and months.

Notizen: Investigations simulating solid-state fermentation, SSF, were carried out to study the influence of a varying N supply on the growth of a mycelium.Experiments with two fungi and two N sources demonstrated the high adaptability of the mycelium to a deficit of nitrogen over a wide range of N supplies. The mycelium of the fungi Gliogladium sp. and Aspergillus sp. can grow up to the very low crude protein content of 11-15%. But protein-poor biomass could not make up the deficit of protein even under optimal cultivation conditions, that means the state of the mycelium remains irreversible. This showed the limit of the adaptability of filamentous fungi, which has to be taken into account for mycelium growth in SSF.

Notizen: The low incidence of antigen-specific B cells in available material is one of the major problems in human monoclonal antibody production. A technique is described which permits the efficient production of specific hybridomas by the separation of specific B cells with magnetic beads prior to fusion.Cells with immunoglobulin γ chains on the surface were enriched from human peripheral blood lymphocytes by separation withmagnetic beads. After electrofusion of the pre-enriched fraction with CB-F7 heteromyeloma cells, the percentage of IgG-producing hybridomas was considerably enhanced. Similarly, B cells with antigen-receptors for α haemolysin from Staphylococcus aureus were enriched by separation with antigen-coated beads. In nine fusion experiments taken together, 153 out of 503 wells contained antigen-specific immunoglobulin after the application of this technique, compared with 37 out of 1584 wells after immortalization of unseparated lymphocytes. The ratio of IgG:IgM-producing antigen-specific hybridomas was slightly shifted towards IgM.Using this technique, antigen-specific hybridomas from lymphocytes of healthy normal donors were established without any artificial administration of antigen.

Notizen: Conversion of starch to ethanol without its prior hydrolysis is of special interest in the treatment of the starch containing waste-waters. In this work the effect of calcium carbonate on the growth and ethanol production from soluble starch by Schwanniomyces castellii NRC 2676 was studied. When the medium was supplemented with 0.1% calcium carbonate the biomass yield and the total starch consumption were increased by 20% and 22%, respectively, while the ethanol yield decreased for 28% in comparison with the control. The rate of biomass production, measured for the period of time between 0 and 24 h, was the highest in the medium with 0.06% calcium carbonate while the rates of ethanol production and starch consumption decreased with and increase in the concentration of that salt; the media with 0.5% and 0.7% calcium carbonate had 3.5 and 5.5 times lower ethanol production rates, and 2.3 and 3.8 times lower rates of starch consumption than the control medium which was not supplemented with calcium carbonate, respectively. The obtained results also showed that the percentage of starch consumed was higher in the media supplemented with calcium carbonate than in the control.Empirical mathematical expressions are given for the relationship of the biomass and ethanol yields to the concentration of calcium carbonate in the medium.

Notizen: The excretion, cellular distribution and pH profiles of invertase in Aspergillus niger CCM 8004 were characterized. An optimized pH control was proposed for conversion of sucrose to gluconic acid and fructose: pH was maintained at 4.5 until the 12th hour and at 5.5 from the 12th hour of fermentation. 300 g · dm3 of sucrose was converted within 31 hours by this procedure.

Notizen: The new yeast species, Sporobolomyces lactosus, transformed D-xylose into a mixture of disaccharides. Hydrolysis of this mixture yielded D-glucose only. The main component of disaccharide mixture was α,α-trehalose.

Notizen: Oats was used as a substrate in tempeh fermentation. The time needed to obtain sufficient mold growth was at least 30 hours at 31°C (Rhizopus oligosporus NRRL 2710). pH was decreasing during the first 32 hours of incubation reaching pH = 5.30. Fermentation of oats led to an increase in water soluble nitrogen, but it did not change protein nitrogen content. R. oligosporus proteinases of optimum pH = 5.50 are postulated to play an important role in oats tempeh fermentation. When a mixture of oats and soybean (1:1) was used, mold growth was faster and the cake tougher. Mixing cereals with legumes to produce good tempeh is recommended.

Notizen: The aim of this paper is to show, how to model the effects of fresh biomass fed in order to avoid a damage of the microorganisms. The continuous ethanol production in a three stage cascade with fed fresh biomass and biomass recycling serves as an example of how information about the design of the start regime, the fresh biomass cultivation and the biomass removal are obtainable by a model containing viability balances.

Notizen: This paper is concerned with the biosynthesis of a high yield of mycotoxin ascochitine by a Ascochyta pisi strain ATCC 66101 on solid substrate with a description of the subsequent procedure of extraction, purification and crystallization. Spectroscopic, chromatographic and antibiotic properties of the mycotoxin are reported.

Notizen: The Rhizobium sp. isolated from the root nodules of Clitoria ternatea L., a leguminous twiner, produced a high amount of IAA (16.4 μg/ml) from tryptophan in an unsupplemented basal medium. The production of IAA started simultaneously with the growth and had no different growth and production phase. The growth and production were parallel and increased up to 45-50 h. The IAA production by the Rhizobium sp. was increased by 520% when the medium was supplemented with fructose (1.5%), MnSO4 (1.0 μg/ml), riboflavin (0.10 μg/ml) and Triton X-100 (0.01%). The possible role of the rhizobial production of IAA on the rhizobia-legume symbiosis is discussed.

Notizen: Seedings of Hypericum perforatum L. have produced multiple shoots on RM medium supplemented with 2.22 or 4.40 μM BAP. Regenerants were evaluated for variability in several morphological characteristics. A comparison with the control showed significant differences in fresh and dry matter and height of plants, but did not effect branching and the number of glands containing dianthrones.

Notizen: Two calorimetric techniques are described allowing us to monitor and control microbial processes at relatively high cell densities: dynamic and continuous calorimetry. These techniques have been applied to study microbial systems, e.g. the dependence of thermodynamic efficiency and heat yield on specific growth rate, the heat yield of mesophilic and thermophilic microorganisms, the oxy-caloric coefficient during aerobic microbial growth, as well as the energetics of the yeast-cell cycle. Such studies are of importance for optimizing biotechnical processes.

Notizen: The mechanism of carbon dioxide saturation of alkaline nutrient medium for the purpose of autotrophic cultivation of microalgae is studied. Carbon dioxide desorption from aqueous solutions of sodium hydrocarbonate is investigated and the influence of chemical equilibria in the solutions on the cultivation of carbon dioxide supply is discussed. It is pointed out that these solutions can be considered to be carriers of the assimilable carbon source for the microalgae cultivation, most efficient at pH 8.5. A comparative estimation of the carbon dioxide and the hydrocarbonic ion as assimilable components of the chemical equilibria under study was done, leading to the conclusion that the more probable component in an alkaline medium autotrophic microalgae cultivation is carbon dioxide. A scheme of bisource feeding of the photosynthetic process, with carbon dioxide for the autotrophic microalgae cultivation in a alkaline nutrient medium, providing a stable and economical cultivation process, is proposed.

Notizen: The thermoacidophilic strain TAC1 was isolated from a sulphatara field. It grows heterotrophically on a synthetic medium, containing yeast extract and carbohydrates at 50 to 70°C and pH 2 to 5. The cells are motile spore-forming rods utilizing, for instance, glucose, lactose, or sucrose as carbon substrate. They also used concentrated whey as nutrient medium.The maximum specific growth rate calculated from batch culture data of the strain TAC1 on glucose is 0.9 h-1 at 65°C and pH 3. The yield coefficient determined in a chemostat culture of the strain TAC1 on glucose, is 0.15 to 0.31 grams of cells produced per gram of glucose consumed (63 to 70°C, pH 2.2 to 4.0, dilution rate 0.2 to 0.4 h-1).The lipid fraction extracted from the cells consists of 72 to 93% of ω-cyclohexyl C17 and C19 fatty acids. The composition of lipid fraction varied with the pH value and the dilution rate but not with the temperature.In regard to the morphology and physiology of the isolated strain as well as the high percentage of ω-cyclohexyl fatty acids of the cell material, the strain TAC1 is similar to Bacillus acidocaldarius.

Notizen: The paper deals with the pectolytic enzymes immobilization on different acrylic supports, and the application of immobilized preparations in the apple juice pectinization process.The correlation between the protein content (Cp) and specific catalytic activities of immobilized enyzme preparations suggest a specific immobilization process only in the case of PONILEX ASH type acrylic supports.The active immobilization degree on PONILEX ASH type supports of Ultrazym 100 G and technical pectinase extract ranged from 99.80 to 296.40% for the Pectinesterase (PE) activity, and from 101.85 to 252.94% for the chain splitting (CS) activity, proving that the ionic immobilization process is a selective one. The simulated operational stability of the immobilized pectolytic enzymes tested by the PE and CS activity values proves the preservation of enzyme catalytic activity.

Notizen: Biotransformation of furfural by Saccharomyces cerevisiae 354 was performed in a sugar cane molasses medium containing salts. The furfural added was rapidly reduced to furfuryl alcohol until a final addition of 3%, without inhibition in the cells growth. An efficient conversion of 96% was obtained by feeding 6 g · l-1 every 6 hours.

Notizen: The ecophysiological properties - light effectuated neosynthesis of biomass from inorganics - make microalgae become interesting organisms of preventive and sanitating environmental protection with regard to the inorganic impact. They are filling an underestimated gap.Medium-term solutions of the heavy metal accumulation in the tertiary sewage disposal, the trophy sanitation of surface and ground waters and of algal induced recultivation of waste-land seem to be attainable.The investigation of the role of microalgae in world-wide material cycles will be of long-term importance to biotechnology and global ecology.

Notizen: Several thermophilic strains similar to Thermus sp. were isolated from a hot spring in Nha Trang (Vietnam), and a domestic hot water reservoir, respectively. They grow aerobically on a complex medium at a temperature of 55 to 70°C and a pH value of 7 to 8. The cells are gram-negative, non-motile and non-sporulating. They possess yellow or red pigments. The isolated strains are similar to Thermus sp. in regard to the composition of the intracellular fatty-acid fraction as well as the absorption spectra of the extracted cellular pigments.

Notizen: Water extracts of pea and soybean stimulated the growth of five tested gas-producing Clostridium strains. When pea and soybean tempeh extracts were used the inhibition effect took place. It is postulated that an antibacterial compound is formed during tempeh fermentation. The stimulating effect might be connected with flatus formation by legumes.

Notizen: Thermostable and hydrophobic β galactosidase of Bacillus sp. TP32 is fixed on zeolithes of controlled hydrophobicity. Thereby, the Si/Al ratio of the zeolithe is an important quantity for controlling the zeolithe hydrophobicity and with it the rate and efficiency of enzyme fixation. The fixation properties improve from NaY via Us(w) to mordenite and Us-Ex.Mordenite β galactosidase is highly active in SOERENSEN phosphate buffer, dodecanole, and ethylene glycole at 70°C using ortho nitrophenyl β D-galactopyranoside (ONPG) as substrate. Further preparations of zeolithe β galactosidase have more or less disadvantages in regard to hydrolysis of ONPG at elevated temperature, as well as rate and efficiency of enzyme fixation exept of Us-Ex β galactosidase in ONPG-containing dodecanole.

Notizen: A new isolated Bacillus strain was cultivated continuously at 68°C and pH 3 for a long time. Extractable lipids represent about 3.6% of cell dry weight and are made up of 18% neutral lipids, 39.3% glycolipids, and 42% acidic lipids. Main components of the fatty acid fraction are ω-cyclohexylundecanoic acid and ω-cyclohexyltridecanoic acid, respectively. MK-7 and hop-22(29)-ene are components of the unsaponifiable fraction. The glycolipid fraction contains the pentacyclic triterpenoid tetrahydroxybacteriohopane.Based on the thermoacidophilic growth conditions, the morphologic and physiological properties, and the nature of lipids, it can assumed that the new isolated strain belongs to the species Bacillus acidocaldarius.

Notizen: The sequence of the effects of delayed and immediate sealed silos as well as the role of nutrient additives such as molasses and/or urea in the ensiling process of rice hulls and the subsequent nutritive value of the product has been shown.There were considerable variations in the chemical constituents during the ensiling of rice hulls among the different treatments under both delayed and immediate sealed silos. In all cases, when compared with the controls, the crude protein, soluble sugars, lactic acid, and fat contents were markedly increased, while the carbohydrate polymers and silica contents were significantly decreased. It was concluded that the treatment of rice hulls + 2% molasses for two months ensiling period under anaerobic conditions can be considered as the optimum conditions for the production of good quality silage from the low grade roughages rice hulls. Changes in pH values also confirmed the improving effect of the combination of molasses addition and the immediate sealing of the silos.

Notizen: The identification and enumeration of yeasts and the effect of chemical preservatives on the yeast load in Nigerian palm wine have been studied. Yeast found largely belong to the genus Saccharomyces. Other genera found were Candida, Endomycopsis, Hansenula, Kloeckera, Pichia, Saccharomycoides and Schizosaccharomyces. The viable yeast count ranged from 0.5 × 107 cfu/ml to 4.2 × 109 in both fresh Elaeis and Raphia spp. of palms. Yeasts in palm wine were least sensitive to sodium nitrate and most sensitive to sodium benzoate. The addition of these two chemical preservatives amongst others reduced the yeast count to 3.2 × 108 (in Raphia sp.), and 4.1 × 109 (in Elaeis sp.) with 0.025% sodium nitrate and 1.2 × 106 (in Raphia sp.) and 1.9 × 107 (in Elaeis sp.) with 0.1% sodium benzoate. The values of the yeast count in bottled and fresh palm wine were between 1.3 × 103 cfu/ml to 9.8 × 106 and 0.5 × 107 to 4.2 × 109, respectively. Maximum values of actual dry and theoretical yeast weights were 1.09 and 42 mg/ml, respectively.