bluuebunny/crossref_metadata_2025 huggingface dataset:
Untersuchungen zur Überproduktion von Tryptophan und anderer Indolderivate durch Hansenula henricii
Authors: Bode R. , Birnbaum D.
Published: December 2004

The cell pools of tryptophan and anthranilate, the excretion of indole‐containing metabolites, and the levels of the enzymes of aromatic amino acid biosynthesis have been determined in regulatory mutants of Hansenula henricii. The strain Hg 48‐2‐M8 produces indoles with a maximum specific productivity of 0.37 mg/g · h at a maximum specific production value of 21 mg/g dry cell weight. This methyl‐tryptophan resistant mutant possess an anthranilate synthase, whose inhibition by tryptophan is reduced. The best conditions for production of indoles are the following: 1% glucose as C‐source; ammonium as N‐source; pH value smaller than 4. We found that under various growth conditions 25–60% synthesized indole‐containing metabolites consists of tryptophan.
Influence of antibiotics and trace salts on lysine production by arthrobacter globiformis
Authors: Sen S. K. , Chatterjee S. P.
Published: December 2004

A hydrocarbon utilizing strain of Arthrobacter globiformis Lb isolated from local soil has been found to yield lysine 3.4 g l−1, keeping the medium optimal for pH, C‐ and N‐sources. Addition of antibiotics and micronutrients to that optimal media stimulated cell growth and enhanced lysine yield.
Antiphytovirale Aktivität von lipophilen Fraktionen aus der Hefe Lodderomyces elongisporus IMET H 128
Authors: Voigt B. , Müller H. , Schuster G.
Published: December 2004

Lipid extract isolated from biomasses of Lodderomyces elongisporus IMET H 128 grown on gas oil 7(B.p. 240–380°C) and fractions of the lipid extract (acetone soluble and fatty acid fractions) reduced the concentration of potato virus X in inoculated as well as in secondarily infected leaves markedly. The antiphytoviral inactive phosphatide fraction was converted into a fraction with high activity by partial hydrolysis with SO2 as acting agent.
Isolierung von Bordetella‐Phagen aus Bakterienstämen der Impfstoffproduktion
Authors: Mebel S. , Rustenbach S. , Lapaeva I. A.
Published: December 2004

It has been demonstrated that strains of Bordetella pertussis used for vaccine production contain temperate phages. It can be conducted from many experiments performed in our laboratory. that 10–100 phages per 1010 bacteria are released. However, the production of bacterial mass is not markedly influenced by lysogeny.

Strains of Bordetella bronchiseptica used for production of vaccine against Rhinitis atrophicans of pigs have temperate phages too. These phages may cause a complete lysis during a submerse cultivation.

The phages of Bordetella pertussis and Bordetella bronchiseptica can be propagted on Bordetella parapertussis.
Proteolysis upon dehydration of yeasts saccharomyces cerevisiae
Authors: Damberga B. E. , Vilcáuns A. P. , Laivenieks M. G. , Beker M. J.
Published: December 2004

The effect of dehydration on proteolysis and activity of proteases A, B and C in the cells of baker's yeast Saccharomyces cerevisiae was investigated. It can be concluded, that under investigated conditions of yeast Saccharomyces cerevisiae drying a decrease of proteases activity takes place. In cells a limited proteolysis takes place which is indicated by an increase in amino nitrogen content and a decrease of tryptophane synthase activity. Adding the protease inhibitor to yeast suspension prevents decrease of tryptophane synthase activity upon dehydration.
Study and theoretical modelling of the drying of the aminoacids – The products of microbial synthesis
Authors: Saduikov R. A. , Migunov V. V. , Karpov A. M. , Golubev L. G. , Pobedimsky D. G.
Published: December 2004

Some properties of the pure aminoacids – the products of the microbiological synthesis as an object of drying are established by the experiments. It is shown that the vacuum‐oscillating drying method is the effective solution of the technological problem of drying the Leucine, Isoleucine, Triptophan and Threonin. The mathematical model of this process is elaborated, whose adequacy is verified by experiments. This model may be used for technological calculations and for technology optimization.
Vergleichende Untersuchungen von verschiedenen Trägermaterialien bezüglich ihrer Eignung für die chemische Oligonucleotidsynthese nach dem Phosphotriesterverfahren
Authors: Weiss R. , Birch ‐Hirschfeld E. , Witkowski W.
Published: December 2004

A number of various oligonucleotides was synthesized on different supports, as well in 3′‐5′, as in 5′–3′ direction. Self made styrene grafted teflones showed some advantages in comparison with commercially available supports.
Analyse von zwei Legumin‐Genfamilien der Ackerbohne (Vicia faba L.)
Authors: Wobus U. , Bäumlein H. , Bassüner R. , Jung R. , Müntz K. , Saalbach G. , Weschke W.
Published: December 2004

DNA clones representing two subfamilies A and B of legum in genes and a recombinant phage containing a complete legumin B gene have been isolated and characterized by DNA sequencing. A DNA fragment harbouring the legumin B gene and adjacent sequences was used for Ti‐mediated transfer into tobacco cells.
Some theoretical considerations on overflow production of metabolites
Authors: Babel W.
Published: December 2004

The overflow production of metabolites appears to be an energy spilling process in terms of life because part of the energy of the primary substrate remains in the metabolite produced. The other part of energy, which is liberated as reducing equivalents and/or ATP along the way to the product, must be wasted. This part is discussed to be responsible for the discrepancies between the theoretically possible and experimentally obtained product yields, because for the wasting process substrate or product are consumed. By reducing the amount of this superfluous energy the product yield should be increased. The auxiliary substrate concept occurs to be an appropriate method.
Partikelelektrophoretische Charakterisierung der Oberflächeneigenschaften von alkanutilisierenden Hefezellen: Chemische Zusammensetzung und Tensidadsorption
Authors: Lerche K.‐H. , Kretzschmar G.
Published: December 2004

By using particle electrophoresis and quantitative analysis the interaction of anionic surfactants (sodium dodecylculfate, sodium decylbenzene sulfonate) with a hydrocarbon‐grown yeast and a commercial baker's yeast has been investigated to obtain further informations about the chemical composition of the surface region (3–6 nm) of the cell wall of this yeasts. A correlation is found between the chemical composition and the different adsorption behaviour of various batches of the same yeasts. It was found that surface‐localized hydrophobic glycoproteins, probably proteophosphomannan are responsible for the strong pH dependent adsorption behaviour of a typical Candida species.

In contrast the cell surface of a typical Saccharomyces species was strongly hydrophilic and showed no surfactant adsorption.

This can be explained by the presence of a polysaccharide probably phosphomannan in the surface region only.

The implication of proteins in the adsorption process is confirmed by model experiments too.

The models for the yeast cell wall proposed by LAMPEN and KIDBY et al. were critically discussed in terms of our results.
Der neue hemmhofmeßautomat HZAA‐3 des autoselect‐systems
Authors: P. Mühlig , Bauer E. , Schicht G. , H. Günther , Harz D.
Published: December 2004

For the automatical measuring of inhibition zones on bioassay plates a new zone reader of the Autoselect‐System has been developed. This third type is described. It combines all advantages of the preceding types as, for instance, the special principle of measuring and the transport of the plates. However, details of the function, the service, and the design have been improved.
Study on the enzyme hydrolysis of waste photoemulsions
Authors: Krysteva M. A. , Peev G. A. , Yotova L. K.
Published: December 2004

Conditions for silver recovery from waste photoemulsions by means of the enzymes trypsin and alkaline protease hydrolysis of the gelatine and the mechanism of process were investigated. The degree of silver regeneration is depending on time during the first minutes. Temperature has a decisive significance only during the initial minutes of the process.

The sedimentation of silver chloride from the enzyme‐degraded photoemulsions depends strongly on the valency of the anions present in the solution.
Naturwissenschaftliche und technologische Aspekte eines mechanisch‐chemischen Strohaufschlußverfahrens
Authors: Mietz M. , Berg F. , Jacopian V. , Philipp B. , Sauer I.
Published: December 2004

To enhance the digestibility of wheat straw as an animal feedstock a partial delignification by action of 1percnt; aqueous alkali in combination with mechanical pre‐ and after‐treatment steps is proposed. On the basis of in vitro digestibility by cellulase the influence of various process parameters on the effect obtained is summarized. Sheep feeding studies comparing original and chemomechanically pretreated straw confirm the suitability of the process‐principle proposed for upgrading cereal straw. The practical feasibility of the process is considered with regard to animal nutrition and technology.
Prototrophic hybrids of bakers yeast. I. Selection of haploids and diploids of prototrophic yeast
Authors: Szopa J. S. , Ołtuszak E.
Published: December 2004

153 haploids, including 8 prototrophs, 12 biotin prototrophs and 4 biotin auxotrophs were isolated from Y, F and FB strains of the baker's yeast Saccharomyces cerevisiae. Remaining haploids were dependent on vitamins of B group other than biotin.

Obtained haploids were characterized by large cell sizes, a or α mating type, the ability to fermentation of sugars and the assimilation of non‐fermented carbon sources.

Haploids obtained from the yeast of Y and FB strains a good growth in the synthetic medium.

Prototrophic haploids, prototrophic haploids with biotin auxotrophs and biotin prototrophs with biotin auxotrophs were crossed. 89 prototrophic hybrids capable of growth in synthetic medium without vitamins were selected out of 178 hybrids obtained.

Hybrids are characterized by features typical for baker's yeast; however, not all of them are capable of sporulation.

As result of selection, prototrophic hybrids and 16 hybrids characterized by a good increase of biomass in molasses medium were chosen.

The efficiency of the biomass of hybrids designated as YY 3040/2, YY 3040/3 and FFB 1910/2 is considerably higher than one obtained from the cultivation of the industrial strain French Mautner (Mf).

All hybrids possess adequate enzymatic activity in anaerobic metabolism of saccharose and maltose.

Selected prototrophic hybrids were sent out to two yeast factories in the country for experimental propagation.
Biochemical studies on the fermentation of cassava (manihot utilissima pohl.)
Authors: Oteng‐Gyang K. , Anuonye C. C.
Published: December 2004

Some original observations have been made on the process of cassava fermentation to produce “foofoo”, a local nigerian diet. During the period of fermentation the pH of the fermenting liquor decreases from 6.1 to 3.4 at the end of the 6th day. The change in pH is uniform throughout the fermentation period. Decreases in dry weight of the fermenting cassava have been recorded; there is a very rapid decline during the third and fourth days of fermentation. Free reducing sugars decrease drastically within the first and second days. Total sugar concentration which is an indication of the starch content of the cassava also declines with fermentation time, and more so during the third and fourth days. Protein concentration in the liquor increases very rapidly during the first and second days of fermentation. It is believed that cassava protein is converted to microbial protein.
Organoheterotrophe Laugung resistenter Materialien
Authors: Iske U. , Bullmann M. , Glombitza F.
Published: December 2004

Leaching processes can be classified in chemolithotrophic and organoheterotrophic mechanisms. In the case of chemolithotrophic leaching sulphide minerals, elemental sulphur, ferrous iron and a number of different reduced metals will be oxidized in a solution containing sulphuric acid of bacterial and/or chemical origin.

Organoheterotrophic leaching however is connected with the accumulation of microbial metabolites such as organic acids, proteins, peptides and polysaccharides, which are capable to disintegrate ores, minerals or industrial wastes through dissolution, formation of complexes or chelates.

Whereas at the present time chemolithotrophic leaching processes are in operation in industrial scale for the winning of copper, uranium and some other special metals, organoheterotrophic processes, their problems and technical applications are still under study.

Therefore problems of organoheterotrophic leaching of chemical high resistant materials such as phosphorus furnace slag and zircon from the Baltic shield have been investigated with regard to possible technical applications for the winning of rare earth elements (REE) and other precious metals.

Using a strain of Acetobacter methanolicus which is able to accumulate large amounts of gluconic acid on the basis of glucose or glucose containing by‐products, leaching effects up to 90% of REE could be realized in the case of phosphorus furnace slag and up to 45% in the case of zircon.
Nitrate removal from drinking water in a fluidized‐bed biological denitrification bioreactor
Authors: Holló J. , Czakó L.
Published: December 2004

In most industrially developed countries an increasing degree of nitrification can be observed in potential water reservoirs. High nitrate content is unacceptable by public health standards. Since contamination seems to be unavoidable, the only realistic solution is purification prior to utilization. One of the potential variations is biological denitrification with a highly intensive facility, a fluidized‐ or expanded‐bed bioreactor. Based on laboratory and pilot plant experiments, a detailed analysis is presented on the problems arising and solutions offered in the construction of a purification system meeting high quality requirements of drinking water purification. The crucial point is selection of the denitrifying microorganisms and organic matter required for denitrification, which simultaneously determines the attachment of bacteria to the support material (autoimmobilization), the intensity of nitrate removal and the character of post‐purification.
A cellulase enzymic product: Industrial processing and possible applications
Authors: Panajotov Ch. A. , Atev A. P. , Stojanov I. M. , Peev P. A.
Published: December 2004

From the Engineering Biology Department of Sofia University' microbiological collection a Trichoderma species mutant strain was found to be most promissing on preparation of cellulase enzymic products. Based on solid‐phase and submerged cultures laboratory and industrial scale procedures for obtaining cellulase products were developed. Different enzyme application possibilities were investigated and the results were presented.
Gas chromatographic analysis of free fatty acids. Part 2: Determination of free fatty acids during anaerobic putrefaction
Authors: Pörschmann S. , Pörschmann J. , Liebetrau L. , Kühn I. , Pätz R.
Published: December 2004

By using tailor‐made capillary columns the changes of the free fatty acid spectrum during anaerobic putrefaction of piggery waste and sludge at pH 5.0–5.5 were examined. Free fatty acids with 18 to 22 carbon atoms were the main components before putrefaction. With progressive fermentation time the share of short chain acids formed from higher acids was increased.
Mikrobiologische Kohleentschwefelung
Authors: Beck D. , Heinritz H.‐J , Worbs M.
Published: December 2004

SO2emissions arising by burning of coal represent an important ecological problem. Therefore, in international scale it is worked today in the development of techniques for solving this problem. A possibility consists in the microbial conversion of sulphur compounds of coal before its burning into compounds which not produce SO2 by burning. Sulphur is bound in inorganic and organic form in coal. The composition may strongly differ in dependence on the kind of coal and its deposit. For the bioconversion of different sulphur compounds specific microorganisms were used. The paper gives an overview about the situation and the tendencies of the research in this field and also some informations of our own research.
Zum Lichteinfluß auf Fermentorkulturen von Nigella damascena L
Authors: Schmauder H.‐P. , Döbel P.
Published: December 2004

The growth behaviour of a Nigella damascena cell line cultivated in airlift fermenters in darkness as well as in ligth was investigated. Considerable variations were observed with regard to the morphology of the cells, the consumption of substrate and the content of yellow pigments. The UV absorption spectra of the yellow pigments show some similarities to the spectra known for thymoquinone.
The influence of control parameters of extraction and concentration over oxidation and degradation of amino acids
Authors: Pobedimski D. G. , Pevzner I. L. , Saduikov R. A.
Published: December 2004

The detailed thermal decomposition characteristics of several amino acids in different fase state — dry and moist crystals (Trp, Arg HCl, Lys HCl), water solutions (Trp) are determined. It is found that thermodecomposition of Trp in water solutions is inhibited by Na2S2O3 and oxyethylidendiphosphonic acid.

The method of finding optimal control parameters (temperatur of moist crystals, heating surfaces, drying agent) during amino acid drying on the bases of their thermodecomposition kinetics is given. The received results can be used for technolodical optimization of different stages of amino acid extraction and concentration processes.
Energy and reducing equivalent potential of C2‐compounds for microbial growth
Authors: Müller R. H. , Babel W.
Published: December 2004

Yeasts were chemostatically cultivated on C2‐substrates. Experimental yield figure were 0.77 g/g and 0.57 g/g on ethanol, 0.37 g/g and 0.29 g/g on acetate and ammonium and nitrate, respectively, as the nitrogen sources. Growth on hexadecane/ammonium yielded 0.94 g/g. Simultaneous utilization of formate lead to an increase of growth yield on acetate and hexadecane but not on ethanol. The experimental data were compared to theoretical figures. These results show that growth yield on ethanol/ammonium is carbon‐limited, on ethanol/nitrate is NADPH‐limited and on acetate with both nitrogen sources is energy‐limited. With hexadecane/ammonium growth yield is energy‐limited too. According to these results ethanol seems to be the only substrate from which an excess in energy can be obtained.
Conversion of lignocellulosic material to ethanol influence of raw material yield and hemicellulose utilization on sales price of ethanol
Authors: Felber J. , Schiefersteiner M. , Steinmüller H.
Published: December 2004

In the late 70's an Austrian Consortium consisting of the STEYRERMÜHL‐Papierfabriks‐ und Verlags AG, the Voest‐Alpine AG and the Universities of Graz was formed to develop a new process for the production of monosaccharides from renewable carbohydrate sources, in particular lignocellulosic material. After detailed examination of various hydrolytic processes it was decided to intensify work on enzymatic hydrolysis. The composition of this group brought the great advantage that it could focus not only on one problem but could also research into the total process. This included pretreatment, enzyme production, hydrolysis, by‐product utilization and energy supply.

The raw materials studied most thoroughly on our program were waste paper and wheat straw, since these lignocellulosics are available in large quantities in Austria.

Until now all endevour to produce ethanol out of lignocellulosic biomass on an industrial scale failed due to uneconomical production. Thus it is evident that the economy of such a process is very dependent not only on the yield of sugar, which is strongly affected by the respective pretreatment, but also on the utilization of the hemicellulose. Summarizing it can be said that the cellulose has to be degregated to a high extent and that the hemicellulose must be utilized to reach a feasible project.
Einwirkung des immobilisierten Präparates „Sirenin”︁ aus Bacillus mesentericus auf Milch als Substrat
Authors: Dobreva E. , Antonova T. , Veltscheva P.
Published: December 2004

Comparative investigations for the possibilities of milk coagulation by the action of soluble and immobilized (on DEAE‐cellulose by adsorption) bacterial enzyme preparation “syrenin” in periods from 30–120 minutes at 5°C are carried out. The milk clotting activities of both preparations are equalized after 40 minutes. The laboratory experiments for producing a bulgarian white brine cheese by the immobilized “syrenin” show a tendency to decrease the losses of substance into the whey and to increase the curdle yields in comparison with these made by soluble preparation.
Biosynthesis of cellulolytic enzymes by Aspergillus niger A.n. 33 and its selectants
Authors: Czajkowska D. , Hornecka D. , Ilnicka‐Olejniczak O.
Published: December 2004

The aim of the investigations was to obtain — from the parent strain Aspergillus niger A.n. 33 — selectants with an increased ability of cellulolytic enzymes biosynthesis. Own selection methods allowed to receive two selectants A.n. 33/2 and A.n. 33/20 characterized by enhanced activities of saccharifying cellulase (respectively 0.11 and 0.14 FPU/cm3), endo‐beta‐1,4‐glucanase (15.4 and 21.8 U/cm3) and cellobiase (0.6 and 1.4 IU/cm3) as compared with the parent strain (FPA — 0.09 IU, CMC — 8.2 U and CB — 0.1 IU/cm3). Moreover, the selectants differed in shape and size of conidial heads, in shape and colour of conidia, as well as in structure and shape of hyphae. Enzyme preparations obtained after ultrafiltration of liquid cultures were characterized by following activites: FPA‐4–16 IU, CMC — 900–1800 U, CB — 60–120 IU and xylanase — 250–280 IU/cm3.
Prozeßberechnung der enzymatischen Saccharosehydrolyse in Abhängigkeit von der Temperatur
Authors: Westphal G. , Vogel J. , Pusch D.
Published: December 2004

The calculation determining enzymatic metabolism under variable reaction conditions is possible on the basis of its reaction kinetics.

In this connection a scientific and mathematical well established model is given, which allows to calculate metabolism that is catalized enzymatically. Experimental evidence for the validity of this model is given for cases both soluble and immobilized Invertase preparation are used. It is substantiated by the fact that the experimental values are in good agreement with the calculated data.
Characterization of biotechnological processes and products using high‐performance liquid chromatography (HPLC). II. Analyses of potato starch hydrolysis products
Authors: Gey M. , Becker U.
Published: December 2004

Potato starch hydrolysis products were analyzed for glucose, maltose, higher oligomeric carbohydrates (to a degree of polymerization, dp 11) and 5‐hydroxymethylfurfural (HMF) using high‐performance liquid chromatography.

For quick qualitative and quantitative analyses short glass columns [12] of high efficiency were useful.

The hydrolyses were carried out by means of enzymes (e.g. α‐ and β‐amylase) or mineral acids. For the acid degradation procedures hydrochloric acid, sulfuric acid and phosphoric acid of different concentrations (0.1…2.0 N) during times ranging from 5 to 60 min at temperatures ranging from 100 to 140°C were used.

Maximum glucose contents (163.4 g/l and 169.3 g/l) were found after 40 to 50 min of hydrolysis in 0.1 N hydrochloric acid heated to 120°C. These values are equivalent to 78.9% or 81.7% glucose yield referred to the initial potato starch amount, respectively. The calculated HMF concentrations were 140 and 180 mg/l.
Morphological properties of Aspergillus awamori strain overproducing glucoamylase
Authors: Witkowska‐Gwlazdowska A. , Ilnicka‐Olejniczak O. , Czajkowska D.
Published: December 2004

It was found that Aspergillus awamori strians suitable for glucoamylase biosynthesis in liquid (LSF) or solid medium (SSF) differ in the shape and size of conidial heads, shape and colour of conidia as well as in the structure and shape of hyphae.
Effects of temperature on microbial production IV. The influence of ethanol on the temperature‐profile curve of ethanol production
Authors: Richter K. , Becker U.
Published: December 2004

The shape of the temperature profile curve of ethanol production changes in the presence of ethanol. So the characteristic points of the curve are shifted to lower values at increasing ethanol concentrations. As a reason for it the potentiation of thermal deactivation effects by ethanol already at lower temperatures is assumed. Compared to it, the activation energy of ethanol for mation in the suboptimal temperature range was found to be unaffected by alcohol.
Einfluß der Kultivierungsbedingungen von Mikroorganismen auf ihre Metallsorption
Authors: Hübner K. , Iske U.
Published: December 2004

The silver sorption capacity of three methylotrophic bacteria and one gelatinotrophic Pseudomonas strain has been investigated in dependence of the cultivation conditions. Whereas the maximum loading capacity of the microorganisms was not appreciable influenced by the variation of the dilution rate in the range between 0.05 h−1 to 0.5 h−1, a change of the carbon source or the modification of the limitation conditions during the chemostatic cultivation process provokes a strong alteration in the sorption behaviour. The maximum silver loading values were obtained, when the microorganisms are cultivated under N‐limitation and the minimum values were measured under P‐limitation.
Modellbank Biotechnologie – Ein Softwarepaket zur Modellauswahl, Optimierung und Simulation biotechnologischer Prozesse
Authors: Goldschmidt B. , Lindner U. , Mathiszik B. , Tiller V.
Published: December 2004

The MODELBASE BIOTECHNOLOGY has been developed for gathering and processing data obtained from biochemical experiments. It covers the analysis of growth kinetics and production kinetics as well and may be used for calibration curve determination too. The implementation of models defined by the user is supported. Both, differential equations and their integrated forms are accepted. In addition to parameter estimation a statistical analysis can be carried on request. Two and three dimensional graphical representation facilitates the interpretation of results.

Fields of application are biochemistry, biotechnology, microbiology, engineering, pharmacy, equipment design, education.
The microbiological data base of the data bank project BD1
Authors: Brüggemann L. , Sommer S. , Fiedler. E. , Karbaum K. , Albrecht C. , Hedlich R. , Nagel B.
Published: December 2004

The aim of the project BD1 (Biotechnology Data Bank 1) is to improve the data processing for research in biotechnology. In BD1, data of several classes of objects and methods are compiled. A data file conception consisting of object data files, method data files and feature data files was created, which can be easily extended to further classes, and which allows the combination of different classes of features to the same class of objects. There are two main approaches to use BD1: 1. making available informations on certain biotechnological objects, 2. the identification of unknown objects by means of their feature pattern.

The microbiological data base and the possibilities of data base search are presented by example of lactic acid bacteria.
Möglichkeiten zur energetischen Optimierung biotechnologischer Massenproduktionsprozesse am Beispiel der Futterhefeanlagen der DDR
Authors: Püchner K. , Hemmann H.‐G.
Published: December 2004

Calculations have been made with the aim of utilizing the waste heat released at constant rates in the large‐scale production of fooder yeast in the G.D.R. and as yet unused, for thermally concentration of fermentation products. The following results were obtained, based on left‐handded thermodynamic cycles and corresponding with the largest production plants working in the G.D.R.

There is the prospect of integrated heat pump systems with direct exposure of evaporator and condenser surfaces and steam‐driven compressors supersending conventional, steam‐heated concentration systems. There is, however, a major hazard in the form of possible breakthroughs of refrigerants into the biosuspension. Processes involving what is known as vaporization cooling and operating without specific refrigeration cycles can presently not compete with conventional systems.

None of the two versions can make full use of the waste heat from fermenters for thermal processing. Recovering between 20 and 30% would be an economical proposition.
Acid phosphatases purified from industrial waste mycelium of aspergillus niger used to produce citric acid
Authors: Żyła K.
Published: December 2004

The waste mycelium of Aspergillus niger ‘Z’ used to produce citric acid was recognized as a rich source of intracellular acid phosphatases (E.C. 3.1.3.2.). Three forms of enzyme were isolated and purified 50–150 fold according to a procedure involving ammonium sulphate fractionation, Sephadex G‐200 gel chromatography, and DEAE‐cellulose ion‐exchange chromatography.

The cytoplasmic form (80% of the whole activity) was found to have molecular weight 230000, ‘MICHAELIS’ constant 2.4 mM (when measured with pNPP), optimal temperature 60°C, pH optimum 1.8–3.0 and contained 30% of carbohydrate in the molecule. This form was able to hydrolyse pNPP, beta‐glycerophosphate, inorganic pyrophosphate, glucose‐6‐phosphate, phytate, compounds and phosvitin, but did not hydrolyse beta‐casein nor leeithin.

One of two forms connected with the cell walls shown similar properties, whereas the other had molecular weight of 9500, ‘MICHAELIS’ constant 1.4 mM, pH optimum 5.0 and was much less thermostable.
Production of L‐tryptophan
Authors: Plachý J. , Ulbert S.
Published: December 2004

A precursor method of L‐tryptophan production using Corynebacterium glutamicum CCM 3358 resistant ot indole was developed. When the dissolved oxygen level was maintained optimal by a periodic pH adjustment and different doses of indole were added the mutant produced 10.5 g/l tryptophan after a 55‐h cultivation.
Live recombinant vaccines for humans
Authors: Fodor I.
Published: December 2004

Vaccines are clearly the most effective means of preventing infectious diseases and have been particularly successful in controlling viral infection. For example, global small‐pox eradication has been the greatest achievement in this regard. However, many existing vaccines are not efficient and there are many diseases against which vaccines are not available at all.
Production of l‐phenylalanine by double auxotrophic mutants of arthrobacter globiformis: Optimization of c and n‐source
Authors: Maiti T. K. , Chatterjee S. P.
Published: December 2004

A number of tryptophan plus tyrosine double auxotrophic mutants isolated by NTG treatment of a glutamic acid prodcing strain of A. globiformis were found to excrete phenylalanine alone in glucose, ammonium chloride, mineral salt medium. Among 24 different carbon sources tested glucose was found to be the best and optimum for ‐phenylalanine production was at 350 mM level. Among 14 different inorganic and organic nitrogen sources tested ammonium chloride was the best and was optimal at 60 mM level for phenylalanine production. On the optimum level of C and N sources a yield of 1.5 g/l phenylalanine was achieved.
A Purified α‐galactosidase from aspergillus niger with enhanced kinetic characteristics
Authors: Agnantiari G. , Christakopoulos P. , Kekos D. , Macris B. J.
Published: December 2004

Extracellular α‐galactosidase from Aspergillus niger was purified 128‐fold over the crude extract by gel filtration, ion exchange chromatography and chromatofocusing. Certain substrates and end products affected enzyme activity. Among the former p‐nitrophenyl‐α‐galactopyranoside (PNPG) inhibited the enzyme at 1.4 mM while melibiose did not inhibit α‐galactosidase at concentrations up to 50 mM. Enzymic end products such as glucose did not inhibit the enzyme at concentrations up to 100 mM while galactose exhibited a competitive inhibition with a Ki = 1.29 mM. The kinetic characteristics of the enzyme compared favourably to other microbial α‐galactosidases and make it suitable for food process applications.
Affinity chromatography of 1,4‐β‐glucosidase from trichoderma reesei QM 9414
Authors: Rogalski J. , Wojtas‐Wasilewska M. , Leonowicz A.
Published: December 2004

The separation and purification method of extracellular cellobiase and aryl‐β‐glucosidase from Trichoderma reesei by means of affinity chromatography on controlled porosity glass activated by ι‐aminopropyltriethoxysilane and oxiranes are described.
Contributions to the biotechnological production of sweeteners from stevia rebaudiana bertoni. II. Induction of stevioside accumulation in cell cultures by variation of the nutrient medium and the analysis of small amounts of stevioside
Authors: Striedner J. , Gutjahr E. , Czygan F.‐C , Braunegg G.
Published: December 2004

Cell cultures of Stevia rebaudiana in general do not contain stevioside when grown on their basal nutrient medium. No stable and prolonged stevioside accumulation was achieved by varying the medium components. However, in some cases a transient state was observed where more stevioside was synthesized than catabolized. The dynamic behaviour of product synthesis which led to accumulation of stevioside during only a short period was demonstrated. For accurate determination of very small amounts of stevioside, a combined TLC‐HPLC method was used [1].
Contributions to the biotechnolgical production of sweeteners from stevia rebaudiana bertoni. III. Accumulation of secondary metabolites by means of a precursor and by elicitation of cell cultures
Authors: Striedner J. , Geissler S. , Czygan F.‐C , Braunegg G.
Published: December 2004

Gibberellin A3 fed to cell suspension cultures of Stevia rebaudiana showed a fast conversion to stevioside. The product was detected within one day after gibberellin addition and achieved its maximum concentration after one week. However, using special production media (without precursor or elicitor), stevioside was produced only two to seven weeks after inoculation [1]. Elicitation of suspension cultures was performed with Stevia specific and non‐specific fungi and with yeast extract. Although production of some secondary metabolites was induced, stevioside was not synthesized.
Effect of ensiling on the nutritive value of low quality roughage rice hulls. II. Chemical studies
Authors: El‐;Sayed O. H. , Shawky B. T. , Zaki D. A. , Mouafi F.
Published: December 2004

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.
Factors in single‐cell protein production from pawpaw fruit pulp extract
Authors: Enwefa C. , Ayanru D. K. G. , Obuekwe C. O.
Published: December 2004

Maximum production of single‐;cell protein (SCP), biomass, chemicals or fuels from microorganisms demands the manipulation of environmental conditions. Consequently, single‐;cell protein production was carried out using Candida sp. and pawpaw fruit pulp extract (substrate), under conditions of varying initial inoculum, different agitation rates, nitrogen sources, and heat treatments. The highest viable cell count of 8.00 ± 1.34 × 1010 colony forming units (cfu)/ml was obtained with substrate supplemented with ammonium sulphate and the least viable cell count of 7.10 ± 2.10 × 106 cfu/ml was observed using urea treated substrate. An optimum viable cell count occurred with an initial inoculum of 5.60 × 105 cfu/ml, conditions of non‐sterilization and agitation at 200 r.p.m. Growth also peaked at 24, 48 and 72 h with varying treatments.
Ultrafiltration of enzyme solutions by means of blood dialyzers
Authors: Luther H. , Hirsch S. , Schuster E. , Balfanz F. , Weber E.
Published: December 2004

Hollow fibres with a symmetrical pore structure as used in artifical kidneys are tested for other purposes. The modules are shown to be suitable for the processing of enzymes such as thermitase, penicillin acylase, uratoxidase, and phosphatase by means of ultrafiltration and diafiltration.

These hollow fibre modules are compared with other modules used in laboratory or in small technical devices. Similar values and material transfer coefficients are calculated.
Continuous production of ligin peroxidase by phanerochaete chrysosporium immobilized on a sintered glass carrier
Authors: Rogalski J. , Dawidowicz A. L. , Wojtas‐Wasilewska M.
Published: December 2004

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.
Bench‐scale calorimetry – application in biotechnology
Authors: Zentgraf B.
Published: December 2004

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.
Bisource carbon dioxide feeding of the photosynthetic process of microalgae autotrophic cultivation
Authors: Sokolov K. , Anguelov S.
Published: December 2004

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.
Immobilized pectolytic enzymes on acrylic supports
Authors: Maxim S. , Flondor A. , Pasa R. , Popa M.
Published: December 2004

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.
Phenomenological principles of microbial lignin degradation
Authors: Härtig C. , Lorbeer H.
Published: December 2004

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.
The volumetric oxygen mass transfer coefficient in antibiotic biosynthesis liquids
Authors: Gavrilescu M. , Roman R. V. , Efimov V.
Published: December 2004

This paper approaches the problem of oxygen mass transfer. This transfer is in antibiotic biosynthesis liquids produced by microorganisms belonging to the actinomycete and fungi classes, which exhibit a shear thinning non‐Newtonian rheological behaviour.

The volumetric oxygen mass transfer coefficients in these liquids (kL ab) change during biosynthesis processes. The change is mainly due to rheological parameter modifications, such as increasing the consistency index (K) and decreasing the flow behaviour index (n). The values of kL ab were 3.0–6.5 times lower than those recorded in water, and their decreasing depended on the kL a values obtained without biological liquid and on the nature of fermentation broths, as well.

Starting from experimental data, two correlations were established between kL ab and P/V,υSG and P/V,υSG, N, respectively. These correlations contain a dimensionless factor (ηam/ηg), which takes into account the rheological properties of the liquid phase and offers the possibility for a fast and sufficiently accurate estimation of kL ab. The empirical correlations developed in the paper correspond reasonably well with the relatively wide variety of experimental data, as in the model proposed by PEREZ and SANDALL, and allow for the comparison of the fermentation batches of the same or different microorganisms; also, they may be applied to the workings of design, scale‐up, control and monitoring of bioreactors.
Catabolic repression and microbial modelling for the yeast Saccharomyces cerevisiae
Authors: Subramanian T. V.
Published: December 2004

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.
Morphological characterization of microencapsulated Penicillium raistrickii i 477
Authors: Irrgang S. , Riemay K.‐H. , Schlosser D. , Schmauder H.‐P.
Published: December 2004

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.
Single cell protein from bagasse pith by a mixed bacterial culture
Authors: Rodriguez H. , Gallardo R.
Published: December 2004

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.
The influence of energy deficiency‐imposing conditions on the capacities ofAcetobacter methanolicus to oxidize glucose and to produce gluconic acid
Authors: Loffhagen N. , Babel W.
Published: December 2004

The presence of dinitrophenol (DNP) during the chemostatic growth of Acetobacter methanolicuson glucose led to i) no significant increase in glucose dehydrogenase, ii) a decrease in the capacity to oxidize glucose by about 30%, not depending on the DNP concentration, and iii) a gradual decrease in the capacity to form gluconic acid, depending on the concentration of the uncoupler. Similar effects of DNP on Acetobacter methanolicuswere observed during the gluconic acid formation process. The loss in the capacity to form gluconic acid is indicated by a drop in the ATP concentration of the cells which cannot be counteracted by the ATP syntheses originating from the oxidation of gluconic acid and of glucose. ATP could be necessary for pumping protons out of the cells that were taken up together with gluconic acid and by the effect of DNP.
Degradation of aromatic compounds by Pseudomonas putida
Authors: Dluhý M. , Šefčík J. , Báleš V.
Published: December 2004

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.