bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological leaching of sulfide minerals with the use of shake flask, aerated column, air‐lift reactor, and percolation techniques
Authors: Puhakka J. , Tuovinen O. H.
Published: December 2004

Four different experimental approaches were used to evaluate the microbiological leaching of ore material containing metal sulfides (Fe, Zn, Ni, Cu, Co) and aluminum silicates. A shake flask technique required the shortest contact time for the complete solubilization of the most readily leachable metals (Ni and Zn). Air‐lift reactors and aerated column reactors required longer contact times and complete solubilization of either zinc or nickel was not achieved. The air‐lift reactor approach was somewhat more effective than the aerated slurry technique. A percolation system was the least effective and yielded the lowest recoveries. Shake flasks (easily autoclavable) offered the advantage of comparison of the microbiological and solely chemical leaching. Aseptic conditions could not be maintained with the air‐lift and aerated column reactors because of contamination via aerosol formation. In a relative scale the leaching patterns were similar in that the precipitation of Fe(III) occurred regardless of the technique; zinc and nickel sulfides were solubilized more quantitatively than those of copper and cobalt; aluminum concentrations, although high, indicated low leaching yields relative to aluminum silicates in the ore material; and the pH reached similar final values in the presence of bacteria.
Continuous production of protein hydrolysates in immobilized enzyme reactors
Authors: Lasch J. , Koelsch R. , Kretschmer K.
Published: December 2004

The digestion of several proteins, casein, α‐lactalbumin, human serum albumin and a mixture of whey proteins by immobilized pronase, thermitase and leucine aminopeptidase was studied on various conditions in five types of enzyme reactors. Reactors and operating conditions were designed to maximize the extent of hydrolysis and to minimize the adverse effects of the macromolecular nature of the substrates. A simple analytical method was developed to follow routinely the extent of hydrolysis. Substrate proteins were subjected to various pretreatments intended to disturb their native structure. The maximum feasible extent of hydrolysis in the reactor effluent, which is an average quantity, clustered around the magic figure of 33% in all systems studied. Protein digestion in bubbled column reactors charged with the polyaminomethylstyrene‐fixed thermostable proteinase “thermitase” and operated at 50 to 60°C turned out to be the most efficient setup to produce continuously amino acid/peptide mixtures.
Wechselwirkungen zwischen Mikroorganismen und Metallionen
Authors: Gehre C. , Iske U. , Glombitza F.
Published: December 2004

Microorganisms are able to interact with metal ions in aqueous solutions and to accumulate considerable amounts of them.

The mechanism of the accumulation depends on the physiological state of the cells. In the case of resting cells the binding reaction takes place on the surface of the cell wall as a sorption process. The kinetic of the sorption processes in dependence of the physiological state of the cells, the concentration of Hg2+ and Cd2+‐ions on the solution and the pH and temperature has been investigated.

Beyond that possibilities for the desorption of the metals from the biomass have been tested.
Recent progress in developing enzyme and tissue‐based membrane electrodes
Authors: Macholán L.
Published: December 2004

The article summarizes the work of this laboratory on the design of eleven types of amperometricpenzyme electrodes mainly based on the CLARK oxygen sensor in connection with cross‐linked oxidases. Special attention is paid to the sensors coupled with plant tissue slice for determining L‐ascorbic acid and phenols. A “second generation” bienzyme electrode is reported which enables tow analytes forming a metabolic couple to be determined simultaneously. A principle of the first useful model of conductimetric enzyme electrode for assaying urea and arginase is also presented.
Immobilization of fungal peroxidase on alkylaminated organic and inorganic porous supports
Authors: Łobarzewski J. , Kolarz B. N. , Wojcik A. , Wojaczynska M. , Trochimczuk A. , Blaszczynska T.
Published: December 2004

Several alkylaminated porous silica gels and acrylic type porous polymers have been used for covalent binding of fungal peroxidase from Trametes versicolor. The immobilization efficiency expressed in terms of the bound protein content, specific enzyme activity, and enzyme storage stability have been determined for both types of supports used. The results indicate a better immobilization ability of organic polymers in comparison with silica gels.
Use of the luciferin‐luciferase assay of ATP for measuring the bacterial growth: Application to Escherichia coli
Authors: Kahru A. , Vilu R.
Published: December 2004

The relative constancy of ATP content per unit of dry biomass in different microorganisms enables to use the specific, sensitive and quick luciferin‐luciferase method for ATP assay for indirect quantitation of microbial biomass by measuring the ATP content in biomass samples.The aim of this work was to investigate the feasibility of using the ATP concentration for the monitoring of the growth of Escherichia coli K 12 W 3350 in different cultivation conditions. Statistically significant high correlation coefficients (r > 0.9) between the ATP content (ATP/ml) and the other growth characteristics examined showed that the ATP content of the culture is as suitable characteristic as the optical density of the culture, total cell number per ml or total cell volume per ml for the monitoring of the growth of E.coliin batch culture in mineral medium with glucose at different growth temperatures (27–42 °C) as well as in fed‐batch culture.
A mathematical approach for the estimation of biomass production rate in solid state fermentation
Authors: Leon J. A. Rodriguez , Sastre L. , Echevarria J. , Delgado G. , Bechstedt W.
Published: December 2004

The oxygen uptake rate (OUR) was studied in a solid state fermentation process of dried citrus peel with the strain Aspergillus niger QH‐2 in order to obtain the growth estimation of the microorganism in the system.

The relationship between OUR, the maintenance coefficient (m) and the yield for oxygen consumption YO2 allows the estimation of the biomass rate if we consider that both parameters are not constants in some periods of the process.

It was estimated that in the first 24th the strain has an specific growth rate of 0.174 h−1 with values for YO2 and m in the order of 2.84 g‐cell/g‐oxygen and 0.006 g‐oxygen/g‐cell ·h respectively.
Experimentelle Untersuchung, Modellierung und optimale Berechnung eines mehrstufigen Säulenfermentors. III. Algorithmus zur computergestützten Berechnung einer optimalen Projektierung für einen mehrstufigen Säulenfermentor
Authors: Kafarov V. V. , Gordeev L. S. , Vinarov A. J. , Semenova E. A.
Published: December 2004

In this third part of the paper a total algorithm for the optimal technological calculation of all processes which occur in an aerobic tower biochemical reactor devided in sections is presented. The algorithm was worked out on the base of a mathematical model [1], experimental data and the calculation of the model parameters [2]. This part of paper also includes the mathematical description of the fermentation process and results of a computer‐aided analysis of the influence of design, hydrodynamic, mass transfer, kinetic factors and energy parameters on the local and global criteria of the optimization.
Fed‐batch cultivation of methanobacterium formicicum and its fluorometric monitoring
Authors: Kuschk P. , Kevbrin V. V.
Published: December 2004

Fed‐batch cultivation of Methanobacterium formicicum Z‐281 was performed under substrate limiting conditions. Specific rate of culture growth amounted to 0.041 h−1, cell yield related to substrate was 0.6 mg proteine/mM formate. Significant increase of coenzyme F420 content in cells depending on time of cultivation was observed. Increase of the fluorescence intensity of the medium was also observed with the accumulation of biomass. These parameters were suggested for tracking culture growth. The possibility of application of fluorescent factors for methanogenic population control in the anaerobic digester is discussed.
Improved brewing and preservation of pito, a nigerian alcoholic beverage from maize
Authors: Onaghise E. O. , Izuagbe Y. S.
Published: December 2004

A controlled brew of pito was produced and compared with a native brew. The former contained a higher alcohol content than the latter brew and was brighter in colour (13 as against 18.5 EBC units) thus making it more attractive. Of various heat and chemical preservative treatments used to prolong the shelf life of both products, pasteurization at 75°C for 30 min. and treatment with sorbic acid at a concentration of 5% were best able to arrest microbial proliferation in the bottled products during a 4 week storage period.
Production of lysine by mutants of escherichia coli K 12 in a medium with lactose
Authors: Sobotková L. , Sikyta B. , Smékal F.
Published: December 2004

In an effort to use whey for lysine production, we isolated from a β‐galactosidase‐hyperproducing strain of E. coli K 12 multiple mutants – auxotrophic, regulatory and penicillin‐resistant. These mutants exhibited for the most part a high reversion rate but some of them produced about 2 mg/ml lysine in an enriched fermentation medium.
Möglichkeiten zur Steigerung der Schwermetallsorptionsleistung von Mikroorganismen
Authors: Iske U. , Hübner K.
Published: December 2004

The sorption capacity of silver on different biological materials has been investigated depending on physico‐chemical pretreatments. The maximum silver loading values measured were compared with the values obtained with nontreated biomasses.

The results show an increase of the loading capacity up to a factor of 10 in case of the alkalitreated biomasses. When the biomasses are extracted before being used as adsorbent with a solvent mixture of chloroform/methanol in a ratio of 2:1 the efficiency of the silver adsorbing power can be increased.

Beyond that, the ability to adsorb silver can also be influenced when microorganisms are used as biocatalysts in a product synthesis before they are used as adsorbents. A strain of Acetobacter methanolicus possesses 1.8 times higher affinity to silver when it is employed in a process of gluconic acid production before adsorption. Physico‐chemical pretreatments influence not only the loading capacity of the biological material, but also the contacting time required for the establishment of the adsorption equilibrium can be considerable reduced.
Simulation of a bacterial population structure in continuous cultivation by a dissociation process: An application to Rhodococcus rubropertinctus
Authors: Drozdov‐Tikhomirov L. N. , Grizhebovskaya A. T. , Mil'ko E. C.
Published: December 2004

An attempt is made to give a quantitative estimation of a possible contribution of the dissociation process in the formation of the heterogeneous population structure for the Rhodococcus rubropertinctus (Micobacterium lacticolum) in continuous cultivation. This estimation is realised with the help of a constructed mathematical model of the process. The model equations obtained describe particular biomass changes for R‐, S‐ and M‐dissociants and changes for substrate (glucose) concentration within the chemostate in continuous cultivation. Next, contributions to dissociant biomass changes were taken into account: (1) cell reproduction (each dissociant has its own specific growth rate depending on the substrate concentration), (2) cell outflow (in proportion to dissociant biomass) and (3) dissociation (dissociant genotype change during reproduction occurs for each dissociant with its own specific frequency).

It is determined that if substrate growth constants are equal the rapidly growing dissociants (possessing maximal μmax) outs the rest of them, and the greater the speed of the flow the less the time to reach a steady‐state distribution of the dissociant biomasses. But, at the same time the slowly growing dissociant can become dominant in the population if it has a lower substrate growth constant.
Biologische Erfahrung mit einem blasenfreien Begasungssystem (CHEMCELL)
Authors: Thalmann E.
Published: December 2004

The increased interest in large scale production of biologically active molecules, as for example monoclonal antibodys, hormones, proteins and enzymes, has stimulated a rapid development of different methods to cultivate eukaryotic cells. Further progress in this field of modern biotechnology is expected not only from the selection of more productive cell lines and more efficient cultivation techniques, but also from the improvement in new bioreactor design and operation, which guarantees increased productivity per unit volume and reduces the downstream processing. Most important factors for a new reactor design in future will be the energy‐ and mass transfer, shear stress and scaleability. The provision of an adequate oxygen supply to large scale reactors is the most critical barrier to scale up. If oxygen is limited in a small degree, the result is inhibition of cell density and cellular efficiency in the production of the desired biomolecules. In addition, when methodologies are used which allow high cell densities and high metabolic active cells, the oxygen transfer becomes more important and, at the same time, more difficult. Since direct sparging of air into the cell‐containing medium causes problems such as shear forces and foaming, new, efficient methods in bubble free aeration must be utilized. A new aeration system is presented, which is suitable to bubble‐free aeration as well to separation of microcarrier‐anchered cells from the harvested medium when running in a continuous perfusion mode. The efficiency of the CHEMCELL System regarding aeration and cell retention is demonstrated by the growth kinetics of BHK 21‐cells in batch and perfusion mode.
Some aspects of the regulation of nitrogen metabolism in the yeast genus candida. Study of the kineties of ammonium transport to the cells of hydrocarbon oxidizing yeast of the genus candida with a change in nitrogen nutrition
Authors: Gradova N. B. , Guselnikova T. V. , Belova A. P.
Published: December 2004

In his study the kinetics of the ammonium transport to he hydrocarbon‐oxidizing yeast cells and the specific features of its regulation as one of the aspects of catabolite nitrogen repression were investigated. As the objects 3 mesophilic strains of C. maltosa, the thermotolerant strain C. rugosa as well as a collection of the thermotolerant strain C. blankii BKM‐Y‐462 type were selected.
Fungal cell walls: Their structure, biosynthesis and biotechnological aspects
Authors: Farkaš V.
Published: December 2004

The article briefly reviews the present knowledge on various aspects of fungal cell wall structure, function and biosynthesis of its individual components. A special attention is devoted to biotechnological potential of cell walls and cell‐wall linked phenomena.
Wirkung eines mikrobiellen Enzympräparates, mit zellwandlytischen Eigenschaften auf Saccharomyces cerevisiae
Authors: Menzel G. , Schöps K. , Klein G. , Häfner B.
Published: December 2004

The effect of an enzyme preparation of Streptomyces spec. KT3 was tested in view of its cell wall lytic activity on cells of Saccharomyces cerevisiae. According to electron micrographs under the influence of the enzyme preparation protoplasts but no spheroplasts were formed. The yield of protoplasts amounted dependent on the enzyme charge to 75–99 per cent, most of the protoplasts were released after 60 minutes. Cells of 12 strains of Saccharomyces cerevisiae were able to be protoplasted and stabilized immediately thereafter by mannitol (0.8 M) or KCl (0.6 M). The presence of stabilizers already in the enzyme‐containing medium inhibited, however, protoplasting considerably. The stabilized protoplasts could be stored for six days at 4°C without any noticeable changes.
Effect of ensiling on the nutritive value of low quality roughage rice hulls. I. Microbial studies
Authors: Shawky B. T. , El‐Sayed O. H. , Zaki D. A. , Mouafi F.
Published: December 2004

Rice hulls were ensiled in laboratory silos in two separate experiments with the same treatments. In the first, sealing was delayed for a period of days. In the second experiment, silos were sealed immediately after filling. In each experiment, four treatments were applied, namely control, molasses 2% added, urea 0.5% added, and molasses 2% + urea 0.5% added.

Lactobacilli, streptococci, and coliforms appear to form the main bulk of the flora characteristic of fresh rice hulls, while the lactic acid bacteria dominate at the commencement of the silage ripening. The characteristics of 30 representative pure strains of both lactic acid and coliform bacteria isolated from rice hulls laboratory silage are described. On the basis of morphological, cultural, and biochemical characteristics, the isolated cultures were identified as ten strains of Lactobacillus ten strains of Streptococcus, five strains of Klebsiella, and five strains of Escherichia.
Production of cellulase in a rotating disc fermenter using immobilized Trichoderma reesei cells
Authors: Sachse H. , Kude J. , Kerns G. , Berger R.
Published: December 2004

The production of cellulase was investigated in repeated batch experiments using immobilized cells of two Trichoderma reesei mutants in a rotating disc fermenter under very low shear stress. The enzyme production with one of the mutants was maintained for three successive batch cycles (ca. 30 days), while with the other mutant the cellulase formation lasted only one batch cycle (14 days) because of a genetic instability.

The enzymatic hydrolysis of microcrystalline cellulose by the cellulase complex formed in the rotating disc fermenter is distinctly higher than that of cellulase produced in a stirred tank reactor, in which the higher shear stress partially damages the enzyme molecules, mainly those of cellobiohydrolase. The higher specific activity of the cellulase produced in the disc fermenter correlates with its higher capacity of adsorption onto microcrystalline cellulose.
In‐Situ recovery of ethanol from fermentation broth by hydrophobic adsorbents
Authors: Einicke W. D. , Gläser B. , Schöoullner R.
Published: December 2004

The in‐situ recovery of ethanol from fermentation by different hydrophobic adsorbents has been studied. Liquid phase experiments have demonstrated that pentasil zeolites have a high selectivity for ethanol in the low concentration range. It is shown that the contact of the fermentation broth with the zeolite NaZSM‐5 avoids the product inhibition. On the other hand, the ethanol production rate dramatically changes in dependence on the glucose‐to‐adsorbent ratio.
Application of UASB‐reactors to industrial waste‐water treatment; performance data and results in granulation control
Authors: Morvai L. , Miháltz P. , Czakó L. , Holló J.
Published: December 2004

Several types of high organic matter pollutants containing (COD‐range: 3–50 kg · m−3) industrial waste waters were treated in laboratory scale (1.2–23 dm3) sludge blanket (UASB) and UASB‐fixed bed hybrid (UBF) reactors. In most cases higher than 80% of COD‐removal efficiency has been attained. The CO2 content of the biogas developed was mainly influenced by the neutralization (base to acid) ratio related to feed pH.

Cell immobilization by granule formation was considered as a change in microbial population: enrichment and aggregate formation of Methanotrix‐like filamentous microorganisms. Based on physiological and physical indexes of microbial selection and with regard to the different sensitivities of microorganisms to substrate inhibition, a new start‐up method was developed for rapid (40–45 days) granulation of raw digested sludge.
Regulatory aspects of carbohydrate metabolism in relation to citric acid accumulation by aspergillus niger
Authors: Steinböck F. A. , Held I. , Choojun S. , Harmsen H. , Röhr M. , Kubicek‐pranz E. M. , Kubicek C. P.
Published: December 2004

Fermentative production by the fungus Aspergillus niger is the world's exclusive source of citric acid to be used for the food, pharmaceutical and detergents' industry. The extraordinary high yields and the delicate nutrient requirements of this process have attracted numerous investigations on its mechanism. This review highlights recent results on the regulation of its biosynthesis, emphazising especially (a) the role of pH, (b) the role of type and concentration of the carbon source, and (c) the role of anaplerotic carbon dioxide fixation in the accumulation of citric acid.
Growth behaviour of filamentous fungi with varying N supply
Authors: Weichert D.
Published: December 2004

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.
Cross flow filtration of RNA extracts by hollow fiber membrane
Authors: Fernandez V. M. , Romano J. M. , Otero M. A.
Published: December 2004

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.
Application of genetic and genetic‐engineering methods to the production of food and food additives
Authors: Leuchtenberger A.
Published: December 2004

The last decade saw remarkable progress in the quantitative and qualitative improvement of microorganisms applied in the foodstuff industry because methods of genetic engineering were used. Compared to the classic methods of mutagenesis and hybridization, genetic engineering facilitates the changing of genes coding for certain products or certain qualities and their new combination with other genes in either the donor or any other host cell.

Success achieved so far in the changing of microorganisms by mutagenesis, hybridization and genetic engineering is explained with some examples. These refer to microorganisms used in the production of enzymes, amino acids, edible organic acids, aromatic and similar products.
Biotechnology based opportunities for environmental protection in the uranium mining industry
Authors: Glombitza F. , Iske U. , Bullmann M. , Ondruschka J.
Published: December 2004

Fluorides and a sodium paraffin sulfonate were used as biocidial substances for blocking microbial oxidation reactions due to chemolithoautotrophic microorganisms and tested in a laboratory and pilot plan scale. A treatment of uranium containing effluents by means of a biosorption process for reducing the uranium concentration was demonstrated in a pilot plant scale too.
Rheological behaviour of some antibiotic biosynthesis liquids
Authors: Gavrilescu M. , Roman R. V. , Efimov V.
Published: December 2004

This paper prsents the results of teh study of rheological behaviour of antibiotic biosynthesis liquids obtained by submerged aerobic cultivation of microorganisms belonging to the actinomycete and fungi classes, in stirred tank bioreactors with turbine impellers. These liquids have a non‐Newtonian behaviour which follows the power‐law rhcological model with a correlation index of over 0.95.

The studied liquids are pseudoplastic, and alter their rheological properties, such as consistency index, (K), flow index, (n), apparent viscosity, (ηa), maximum Newtonian viscosity (η0), with the culture age, microrganism strain and batch conditions. Also, these liquids are time dependent, exhibiting thixotropy.

The most viscous liquids are produced by Streptomyces aureofaciens and Streptomyces rimosus cultivation, while that produced by Streptomyces griseus is the least viscous. A higher pseudoplasticity appears after 30 hours culture age.

Since all these biosynthesis are aerobic, a careful observation of the rhelogical behaviour dynamics is necessary to avoid the oxygen culture supply limitation and the decrease of the bioreactor performance during biosynthesis.
Influence of sulphur dioxide on the fermentation of sulphite spent liquor
Authors: Mohrmann K.‐H. , Fischer K.
Published: December 2004

In fodder yeast production from sulphite spent liquor, sulphur dioxide is well‐known as a yeast poison. The present paper deals with the detailed influence of sulphur dioxide.

The experimental work was done in a laboratory fermenter under technical conditions. A decrease in biomass yield, and an increase in oxygen consumption, caused by increasing carbon dioxide production, were found.

During the fermentation, there is no destruction of the carbonyl‐bisulphite adduct to be observed. Sulphur dioxide has no influence on the crude protein content of yeast cells, and there is also no influence on the morphology of cells.
Age structured process modelling of a fermenter cascade with feed of fresh biomass
Authors: Kuse B. , Loettel W.
Published: December 2004

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.
A thermoacidophilic bacterium similar to Bacillus acidocaldarius
Authors: Zentgraf B. , Rogge G. , Nagel B.
Published: December 2004

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.
Fed‐batch production of concentrated fructose syrup and ethanol using Saccharomyces cerevisiae ATCC 36859
Authors: Koren D. W. , Duvnjak Z.
Published: December 2004

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.
Hemicellulolytic enzymes of the ligninolytic white‐rot fungus Phlebia radiata. Influence of phenolic compounds on the synthesis of hemicellulolytic enzymes
Authors: Rogalski J. , Hatakka A. , Longa B. , Wojtaś‐Wasilewska M.
Published: December 2004

The ligninolytic fungus Phlebia radiata growing in a low‐nitrogen medium with wheat bran as the sole carbon source was induced by some lignin monomers, e.g. vanillic, veratric and ferulic acids. In the medium these substances showed a mainly stimulating influence on the hemicellulolytic enzymes activity except for arabinofuranosidase and ferulic acid esterase.
Investigation of the bacitracin biosynthesis in an airlift bioreactor
Authors: Gavrilescu M. , Roman R.‐V.
Published: December 2004

Results of pilot plant studies using an external‐loop airlift bioreactor (170 l fermentation volume, liquid height‐to‐riser diameter: 27, loop‐to‐tower cross‐section‐area: 0.1225) have proven the relative merits of such a system in the bacitracin biosynthesis produced by the Bacillus licheniformis submerged aerobic cultivation.

The results were compared to those obtained in a pilot‐scale stirred‐tank bioreactor with the same values of kLa. Excepting the aeration rate of 0.2 vvm, the fermentation process performed at 0.5 vvm and 1/0 vvm, respectively, unfolded similarly in the two fermentation devices with respect to the cell mass production, substrate utilization and bacitracin production during the fermentation process.

In the riser section of the airlift bioreactor, the dissolved oxygen levels were higher, while in the downcomer section they were lower than those realized in the stirred tank bioreactor.

Power requirements of the airlift fermenter were by 17–64% lower than those for a mechanically agitated system, depending on the aeration rates, which led to an important energy saving.

Moreover, the lack of mechanical devices in the airlift system provides safety and a more gentle environment for the cultivation of microorganisms.
Staining procedures for flow cytometric monitoring of bacterial populations
Authors: Müller S. , Lösche A. , Bley T.
Published: December 2004

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.
Investigations into the growth behaviour of a toluene‐degrading Pseudomonas strain, taking the high vapour pressure of toluene into consideration
Authors: Löser C. , Ray P.
Published: December 2004

A toluene‐degrading Pseudomonas species isolated from waste water was studied with regard to its growth behaviour. The dependence of the growth rate on the pH value, on the toluene concentration and on temperature, as well as the O2 consumption of the isolate were determined. The fact that toluene is a highly volatile substrate, which is present both in the liquid and in the has phase of a reactor, was considered in the experiments. It is shown that the volatility of toluene has to be taken into consideration for an accurate determination of the toluene concentration in the medium.
Enhancement of methionine production by methionine analogue ethionine resistant mutants of Brevibacterium heali
Authors: Mondal S. , Chatterjee S. P.
Published: December 2004

In order to improve the methionine yield of the isolate B. heali, attempts were made to isolate mutants resistant to the methionine analogue DL‐ethionine after mutagenesis with N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (NTG). The minimum inhibitory concentration (MIC) of ethionine for B. heali was found to be 2 mM. After mutagenesis and screening, five mutants resistant to 50 mM of ethionine were isolated. The yield of the best ethionine resistant mutant, B. heali Br EthR, was 13 mg/l of methionine medium under optimum cultivation conditions.
Heavy metal sorption by marine algae and algal by‐products
Authors: Sandau E. , Sandau P. , Pulz O. , Zimmermann M.
Published: December 2004

All the oceans are plentiful with marine algae. Non‐viable marine macroalgae are able to adsorb heavy metal ions. Compared with other biosorbents, such as fungi, bacteria, yeasts and microalgae, they have the advantage of being easily available, cheap and having high heavy metal sorption capacities. The by‐products of marine phaeophyceae are even more cost‐effective heavy metal biosorbers.

Experiments of heavy metal sorption using non‐viable Fucus vesiculosus, Ascophyllum nodosum and algal by‐products were carried out to investigate the factors influencing and optimizing the heavy metal biosorption.

The pH value, biomass concentration, heavy metal concentration, heavy metal species, competing ions, algal varieties and time were the most decisive parameters. The sorption isotherms showed increasing sorption capacities and decreasing sorption efficiencies with an increase in the initial heavy metal concentration. Sorption kinetics of different metals were established. Biomass concentration influenced the sorption efficiencies very much, but reduced the sorption capacity per g biomass. The pH value controlled the sorption (pH 3–7) and desorption (pH 1–2) decisively.

Beside heavy metal contaminated model waters, actual industrial effluents were treated successfully by algal sorbents in batch experiments and continuous column tests.

Transmission electron micrographs of different contaminated and untreated algal specimens are available.
Investigations into the antibiotic activity of tea fungus/kombucha beverage
Authors: Steinkraus K. H. , Shapiro K. B. , Hotchkiss J. H. , Mortlock R. P.
Published: December 2004

Tea fungus/kombucha, an acetic acid flavoured fermented tea beverage, is widely consumed in various parts of the world and has more recently become a fad in the United States. This is due in part to the fact that it can be produced in the home, and it is reported to be medicinal, effective against arthritis, psoriasis, chronic fatigue, constipation, indigestion and metabolic diseases. Among 264 references from 1852 to 1961, there are reports of antibiotic activity against Agrobacterium tumefaciens and medicinal value against a variety of diseases. The medicinal value appears to be related to that attributed to vinegar, one of our most ancient foods. We decided to test tea fungus/kombucha for its antibiotic activity against Helicobacter pylori, a primary cause of gastritis related to peptic ulcers and gastric carcinoma, Escherichia coli, Staphylococcus (Micrococcus) aureus and Agrobacterium tumefaciens. Tea containing 4.36 g of dry tea per litre and 10% of sucrose and fermented with the tea fungus showed no antibiotic activity in the beverage beyond that caused by acetic acid, a primary product of the fermentation.
Application of an airlift bioreactor to the nystatin biosynthesis
Authors: Gavrilescu M. , Roman R.‐V.
Published: December 2004

Pilot plant studies were performed using a concentric‐tube airlift bioreactor of 2.5 m3 fermentation volume. The results have proven the relative merits of such a system in the biosynthesis of nystatin, produced by Streptomyces noursei, in submerged aerobic cultivation and batch operation mode. The results were compared to those obtained in a pilot‐scale stirred tank bioreactor of 3.5 m3 fermentation volume.

The fermentation processes in the two fermentation devices were similar with respect to substrate utilization, biomass production and nystatin biosynthesis.

In the riser section, the dissolved oxygen concentration was higher than that in the downcomer.

The volumetric oxygen mass transfer coefficient was dependent on the rheological behaviour of the biosynthesis liquids, which was not constant during the fermentation process.

The total energy consumption for nystatin production in the airlift bioreactor was 56% of that in the stirred tank, while the operating costs represented 78% of those in the stirred tank bioreactor.
Ethanol fermentation of HTST extruded rye grain by bacteria and yeasts
Authors: Czarnecki Z. , Nowak J.
Published: December 2004

High temperature extrusion cooking of rye was used as a pretreatment for ethanol fermentation, and yeasts and bacteria were compared for their fermentation rates. Extrusion cooking caused, on average, a 7.5% increase in ethanol yield in comparison to autoclaved samples. The best results were achieved for grain with a moisture of 21‐23% which was extruded at temperatures of 160‐180 °C.

Extrusion decreased the relative viscosity of rye grain water extracts, so it was possible to mash it without α‐amylase. The efficiency of fermentation of extruded rye without Termamyl was equal to that of autoclaved and traditionally mashed rye (using α‐amylase).

The rate of fermentation of extruded rye grain by Zymomonas was higher during the first stage, but the final ethanol yield was similar for the bacterium and the yeast.

Though both microorganisms gave good quality distillates, the concentration of compounds other than ethanol achieved from extruded rye mashes, which were fermented by Z. mobilis, was five times lower than for yeasts.
An advanced method based on artificial intelligence for controlling biotechnological processes (part II)
Authors: Sarkisjants L. , Krishtapsons M.
Published: December 2004

A new finite‐state method is proposed which has been designed for use in biotechnological processes, in particular for the control of the pH in acidic waste water.

The automation of expedient behaviour takes into account the non‐linear character of the process and a good control stability in spite of variations in the influent acidic concentration, dissociation constant of the acid and change of the pH set point.

To design the controller with the proposed method, no model of the process is required. Simulation studies show that expedient behaviour of an automaton in a random medium for the control of the pH neutralization process can give a good performance.
Transformed root cultures for biotechnology
Authors: Wysokinska H. , Chmiel A.
Published: December 2004

This review is concerned with the application of hairy roots, i.e. plant roots formed from plant cells after transformation by Agrobacterium rhizogenes for the production of bioactive compounds. Transformed root cultures have been established from numerous species of dicotyledonous plants. The plants, as well as the main products accumulated in hairy root cultures derived from these plants, are listed in this paper. Data are presented on novel compounds, hitherto detected only in transformed roots but not occurring in the corresponding intact plants.

The possible use of hairy root cultures for the over‐production of secondary metabolites and biotransformation of chemicals is discussed. In order to enhance the productivity of hairy root cultures, various methods have been derived, and optimized procedures are proposed. They include selection of high‐producing clones, elicitation, composition of growth media, culture conditions and genetic approach. Hairy roots usually store secondary metabolites in vacuoles inside the cells. Therefore, several methods have been used to increase the amount of products released into the medium. Unfortunately, no general procedure is known that works in all cases, and the excretion behaviour of hairy root cultures varies from one species to another and even within one species from one clone to another.

Special attention is given to the cultivation methods and bioreactor systems for hairy root cultures. Hairy roots are cultivated usually in shake flasks; however, shake flask culture is not suitable for the complex optimization and continuous control of the culture conditions. In this paper, we are going to present bioreactors proposed for the cultivation of hairy roots under more or less controlled conditions. Modifications of typical bacterial bioreactors, i.e. stirred tanks, airlift loop reactors and other constructions, are presented. A very special type of bioreactor providing good conditions for loose root mass multiplication without oxygen or substrate limitations, is the mist bioreactor. Nowadays, it is practically impossible to select the one best bioreactor type for hairy root culture.
Estimation of biological kinetic parameters from an analysis of the BOD curve of waste waters–effects of a chemical preoxidation
Authors: Beltrán F. J. , Garcíaaraya J. F. , Álvarez P.
Published: December 2004

Urban waste waters were treated with pure ozone or combinations of ozone, hydrogen peroxide and/or UV radiation to study the course of resulting BOD (biological oxygen demand)‐time profiles and to propose a kinetic model. BOD‐time profiles of chemically treated waste waters show an initial lag period that first order kinetic models cannot describe. A second order kinetic model is then proposed that satisfactorily fits experimental BOD‐time profiles, except when hydrogen peroxide has been used. In these cases, BOD‐time profiles present the highest lag periods observed. By applying this model, three parameters are determined: the biokinetic constant (k) which is an index of the biological removal rate; the potential amount of biodegradable matter (BODT), and the measure of the size of inocula and microbial activities of microoganisms (λ). The model was checked with experimental results of BOD‐time profiles corresponding to both untreated and chemically ozonated urban waste waters. Ozonated waste waters showed the highest values of k and BODT, which implies an improvement of waste water biodegradability after ozonation. However, values of λ corresponding to ozonated waste waters presented lower values than those of untreated waste waters. This was due to the lag period observed in the BOD‐time profile, which was a consequence of a lack of microorganism acclimation to ozonated waste waters. The effect of the ozone does, pH and carbonates during ozonation on COD (chemical oxygen demand) and the above indicated parameters was also studied. There was an optimum ozone dose which was 138 mg/l for this specific system. This led to the highest biodegradable fraction (φ) and the highest biokinetic constant (39% increase in φ and 4.7‐ fold increase in the value of k, respectively, compared to untreated waste waters.). Another significant fact was that a higher COD reduction was observed in the absence of carbonate during ozonation at basic pH values. In addition, the percentage of variation in the biodegradable fraction (Δφ) of ozonated waste water increased compared to the untreated waste water at acid pH. The results suggest that ozonolysis, the direct molecular ozone way of reaction, due to its selective character, increases the biodegradability of waste water more than other chemically advanced oxidation processes based on hydroxyl radical reactions.
Isolation of phenoxy herbicide‐degrading Rhodoferax species from contaminated building material
Authors: Ehrig A. , Müller R. H. , Babel W.
Published: December 2004

Bacterial strains have been isolated from contaminated concrete debris which exhibit the metabolic capability to degrade 2,4‐chlorinated and 4‐chloro‐2‐methyl‐substituted phenols and phenoxyalkanoic acids including phenoxyacetate and phenoxypropionate derivatives. These strains were taxonomically identified. Two of them were found to belong to the β‐subgroup of the proteobacteria and showed strong similarity to Rhodoferax fermentans. Preliminary investigations by PCR amplification using respective primers revealed that the strains harbour tfdA‐like gene sequences.
A comparison of methods for DNA extraction from paraffin‐embedded tissue for microsatellite instability analysis by polymerase chain reaction
Authors: Kullmann F. , Schölmerich J. , Bocker T. , Rüschoff J.
Published: December 2004

In a prospective study, nuclear DNA was extracted from colorectal tumours and normal mucosa which had been fixed in buffered formalin and embedded into paraffin. DNA‐extraction was performed using three different methods: a commercial kit which was not especially created for this use; a known fast procedure without DNA‐cleaning steps; and a more conventional DNA‐preparation protocol with DNA‐cleaning. Using the polymerase chain reaction (PCR), DNA was amplified by being targeted onto two β‐globin fragments with different lengths (536 bp and 989 bp) and (CA)n repeats localized on chromosome 5q (D5S346) and chromosome 17p (TP53CA) with a length of about 100 bp for detection of microsatellite instability. The success rate of microsatellite amplification was 100% with all methods. The 536 bp β‐globin fragment could be amplified with a success rate ranging from 40% to 100%. The amplification of the 989 bp β‐globin fragment was unsuccessful. Significant differences were observed between the three methods in the final DNA concentration and DNA yield. In microsatellite instability studies of paraffin‐embedded tissues, the investigator can expect a high success rate of nearly 100% using any of the described methods.
Immobilization of glucoamylase on polyamide nets
Authors: Miller E.
Published: December 2004

The formation of reactive groups on polyamide nets (nylon 6) and the subsequent immobilization of glucoamylase were investigated. Different mesh sizes of the nets and two chemical methods of enzyme coupling ‐ i( partial hydrolysis of the polyamide with subsequent glutaraldehyde binding and ii) O‐alkylation of the carrier using a treatment with a benzene‐methyl sulphate mixture – were used. The reactivity of immobilized glucoamylase (GA) was tested by hydrolysis reactions using 1% starch solutions. The highest reactivity (140 μg glc/)min × cm2 was obtained for methylated nylon samples attached to a glass rod and by coupling glucoamylase on the nylon surface which had been treated with lysine and glutaraldehyde. This method resulted in a more reactive and more stable preparation of immobilized glucoamylase as compared to a simpler method of coupling glutaraldehyde to partially hydrolyzed nylon.
Ethanol production from native cassava starch by a mixed culture of Endomycopsis fibuligera and Zymomonas mobilis
Authors: González C. , Delgado O. , Baigorí M. , Abate C. , Callieri D. A. , De Figueroa L. I. C.
Published: December 2004

The conversion of starch from unhydrolyzed cassava flour to ethanol by a pure culture of Endomycopsis fibuligera and by a co‐culture of this amylolytic yeast and the bacterium Zymomonas mobilis was studied.

The best overall results were obtained using the mixed culture. After 96 h of fermentation of a medium containing 150 g/l initial cassava starch, an ethanol concentration of 31.4 g/l, a productivity of 0.33 g ethanol/l × h and a yield of 0.21 g ethanol/g initial starch were reached. The highest yield (0.37 g/g) was obtained after 48 h when using a medium containing 50 g/l initial starch.
Hydrolysis of cellobiose using β‐glucosidase from Penicillium funiculosum. Kinetic analysis
Authors: Romero M. D. , Aguado J. , Rodriguez L. , Calles J. A.
Published: December 2004

The kinetics of cellobiose hydrolysis was studied using β‐glucosidase from Penicillium funiculosum, both free and immobilized on nylon powder, at different temperatures, pH values, enzymatic activities and initial cellobiose and glucose concentrations.

The experimental results were fitted to a kinetic model by considering the substrate and product inhibitions as well as the thermal deactivation of β‐glucosidase with a mean deviation of less than 10%. The immobilization of β‐glucosidase led to an increase in the stability of the enzyme against changes in the pH value.