bluuebunny/crossref_metadata_2025 huggingface dataset:
Phlebia radiata laccase forms induced by veratric acid and xylidine in relation to lignin peroxidase and manganese‐dependent peroxidase
Authors: Rogalski J. , Leonowicz A.
Published: December 2004

White‐rot basidiomycete Phlebia radiata grown in the nitrogen‐poor liquid medium was tested for the inducing effect of 2,5‐xylidine and veratric acid on laccase production and properties of its preparations. Also lignin peroxidase and manganese‐dependent peroxidase were assayed under the same conditions. The maximum of laccase activity for veratric acid as a stimulator was done much earlier than that of xylidine. It was very sharp and disappeared quickly. At that time only weak lignin peroxidase and manganese‐dependent peroxidase activities were noticed. The maximum of laccase induced by xylidine was observed much later and kept longer. Both laccase preparations showed the same properties. For biotechnological reasons, the production of laccase induced by the nontoxic veratric acid is much more economic and better acceptable than that induced by xylidine.
The growth conditions of cephalosporium eichhorniae for the conversion of starch substrates to protein
Authors: Nguyen Van Ba B. , Bednarski W. , Kowalewska‐Piontas J. , Tomasik J.
Published: December 2004

The protein synthesis by Cephalosporium eichhorniae on substrates containing starch was evaluated at different pH, moisture content, ammonium sulphate and potassium dihydrogen phosphate supplementation. The optimum pH level was about 4.2 and the moisture content 65%. The optimum level of supplementation of medium containing sweet potato substrate with (NH4)2SO4 was smaller than that for cassava substrate (5.2 g/l < 6.7 g/l in submerged culture, and 4.0% < 5.2% in solid state fermentation). The total crude protein yields were about 7.6 g/l for submerged cultures and 12% DM for solid state fermentations.
Permeabilization of covalently immobilized saccharomyces cerevisiae
Authors: Jirků V.
Published: December 2004

The effect of solvents, ionic detergent, and drying on the passive membrane permeability of free and immobilized yeast cells was studied. The immobilization by covalent linkage was shown to affect the membrane composition as well as the individual susceptibility of cells to a permeabilization procedure.
Immobilization of β‐glucosidase from different sources on nylon tube
Authors: Woodward J. R. , Radford A. , Rodriguez L. , Aguado J. , Romero M. D.
Published: December 2004

Cellulase from four different fungi and β‐glucosidase from almonds were immobilized on the inner surface of nylon tubing. The highest values of β‐glucosidase activity retention on the support were obtained when P. funiculosum and N. crassa were used as the enzyme source. A comparative study of the thermal stability referring to β‐glucosidase activity was developed using free and immobilized enzymes. The most stable β‐glucosidases (from P. funiculosum and A. niger) did not show an appreciable change in its thermal stability after immobilization. An important increase in thermal stability was observed when less stable β‐glucosidases (from T. reesei, N. crassa and almonds) were immobilized.
Flow‐cytometric investigation of sterol content and profliferation activity of yeast
Authors: Müller S. , Lösche A. , Bley Th.
Published: December 2004

To understand and control the dynamics of microbial growth and metabolism, a theoretical background based on segregated models is necessary, and therefore flow cytometry is the suitable measuring method.

It is shown that additional information to the usual mean‐value information, and to the well‐known cytometric methods for determining DNA content and size/shape measurement by scattered light, like the distribution of membrane sterol content of baker's yeast, leads to a more detailed knowledge of growth dynamics.

We have found, that a low content of membrane sterols is a characteristic of cells with suppressed proliferation activity, but necessary for high fermentation activity. Also, a high content of membrane sterols seems to enhance the viability and survival capability of harvested and dryed baker's yeast cells. Therefore, we recommend harvesting cells at a point of medium content of membrane sterols.
Biotransformation of furfural by yeast cells covalently bound to cellulose granules
Authors: Ivanova N. , Yotova L.
Published: December 2004

A covalent binding to cellulose granules of two yeast strains Candida tropicalis and Trichosporon cutaneum was achieved. The maximum activity for destroying furfural by the immobilized cells was obtained when the procedure conditions were: reaction medium at pH 5.0, 20°C and cell suspension concentration of 80 mg/ml. The continuous furfural transformation was studied using a growth medium in a fermenter with immobilized Trichosporon cutaneum in which a 84% bioconversion was achieved. The reduced values of furfural remained constant even after 10‐fold transformation.
The influence of pressure on the growth of methanotrophic bacteria
Authors: Wendlandt K.‐D , Jechorek M. , Brühl E.
Published: December 2004

The growth rate and the maximum cell concentration of methanotrophic bacteria are limited by the transfer of methane and oxygen to the culture fluid. The operation under moderate pressure results in an increase in driving force for the mass transfer of both nutrients and, therefore, in a large increase in the attainable biomass concentration.

Our laboratory pressure fermenter with a volume of 12 litres operates under a system pressure of up to 0.5 MPa. In this reactor a maximum productivity of 6 g biomass/lh is achieved. However, operating under moderate system pressure and exhaust gas recycling has also disadvantages because the concentrations of the gas phase components may inhibit the growth process.

From the results of the laboratory fermenter we have developed kinetic models of the influence of dissolved oxygen and carbon dioxide on the specific growth rate of the methanotrophic strain GB 25. These models are the basis for processing under increased system pressure and exhaust gas recycling.
Nutrition and broth alterations in the lactic acid fermentation
Authors: Heriban V. , Sitkey V. , Šturdík E. , Matuš P.
Published: December 2004

In order to optimize the thermophilic lactic acid fermentation on saccharose as the sole carbon source and improve the effectiveness of the process, alternative nitrogen sources were tested and a minimal broth composition was found. Of the alternative nitrogen sources, whey protein hydrolyzate (WPH) was the best; the broth composition was reduced from seven down to three items. Application of ammonium as a neutralizing agent instead of sodium hydroxide brought an important positive change.
Oxygen transfer efficiency in the biosynthesis of antibiotics in bioreactors with a modified RUSHTON turbine agitator
Authors: Roman R. V. , Gavrilescu M.
Published: December 2004

In this work, the oxygen mass transfer efficiency and power consumption in a non‐biological system and an antibiotic biosynthesis process, using a modified RUSHTON turbine agitator, were investigated. It was demonstrated that a simple modification of the blades through the increase of the blade height, simultaneously with the discontinuation of the blade surface, could improve the oxygen transfer efficiency by about 30%.

Experiments performed in stirred tank bioreactors with an overall volume of 20 m3, equipped with the modified RUSHTON turbine agitator, showed that the power consumption diminished by a factor of 1.18 to 1.6 during the fermentation processes of Streptomyces erithreus, Streptomyces griseus, Streptomyces noursei, and Nocardia mediaterranei, compared to the witness bioreactor.

The use of the modified RUSHTON turbine for the antibiotic biosynthesis process may contribute to the decrease of the overall costs and the obtainment of better productivity, allowing an intensive utilization of power inputs for aeration and agitation.
Optimization of the conditions of the fermentation of beet molasses to lactic acid by Lactobacillus delbrueckii
Authors: Monteagudo J. M. , Rodríguez L. , Rincón J. , Fuertes J.
Published: December 2004

Optimization studies were carried out for the production of L‐lactic acid from the fermentation of beet molasses by Lactobacillus delbrueckii. A Central Composite Design was used to determine the optimum values of the process variables (temperature, pH, inoculum concentration, and initial sucrose concentration) for obtaining the maximum yield and the maximum volumetric productivity of lactic acid. Among the variables selected for study, it was found that all of them apart from the temperature significantly affected the responses (yield and volumetric productivity of lactic acid). The Central Composite Design also permitted formulating two second‐order polynomial empirical models relating to the responses and the significant variables. From these models it was possible to determine the value of the variables giving the maximum yield of lactic acid production (87.8%) and the maximum volumetric rate of lactic acid biosynthesis (2.7 g/l · h). Finally, the dependence of the lactic acid yield and productivity on the model variables was investigated. All conclusions are restricted to the experimental range studied.
The variability of the hypericin content in the regenerants of Hypericum perforatum
Authors: Čellárová E. , Kimáková K. , Halušková J. , Daxnerová Z.
Published: December 2004

The hypericin content of in vitro regenerated plants of Hypericum perforatum L. was determined by spectrophotometry. A significant variability of some of the morphological characters, of the biomass production and the hypericin formation was found within the somaclones of the same genetic origin and among the regerants of different genotypes. The concentration of BAP which promoted the shoot differentiation did not affect the hypericin content and the gland density. New information on the ultrastructure of hypericin‐containing multicellular glands is presented here.
Biotechnological methods for the up‐grading and modification of animal waste fats
Authors: Bednarski W. , Adamczak M. , Kowalewska‐Piontas J. , Zadernowski R.
Published: December 2004

The possibility of producing monoacyloglycerols (MAGs) from poultry fat or beef tallow using selected microorganisms or enzymatic glycerolysis was established. The highest content of MAGs (16.21–17.63% w/w) in the lipids was obtained after the cultivation of Candida lipolytica on a medium with poultry fat. The concentration of MAGs in the lipids which remained in the medium was influenced by the microorganisms strains and their cultivation conditions. The yield of MAGs obtained by the enzymatic glycerolysis of poultry fat or beef tallow ranged from 3.52% to 55.10% w/w, respectively.
Formation of a micronuclei‐like structure induced by colchicine treatment in Saccharomyces cerevisiae
Authors: Toyama H. , Toyama N.
Published: December 2004

Minute nuclei named “smaller nuclei” were generated when the cells of Saccharomyces cerevisiae were treated with colchicine. The formation of “smaller nuclei” seemed to be related to nuclear division because those nuclei were only produced under conditions suitable for nuclear division. The fact that the average DNA content of “smaller nuclei” was almost one tenth of that of the isolated normal diploid nuclei showed that the “smaller nuclei” are not condensed nuclei but aneuploid nuclei like micronuclei in animal cells. It appeared therefore likely that a micronuclei‐like structure could be produced by colchicine treatment in S. cerevisiae.
Production of thiaminase I for analytical purposes
Authors: Ruml T. , Silhánková L.
Published: December 2004

A simple medium enhancing the production of thiaminase I (EC 2.5.1.2) by Bacillus thiaminolyticus was developed. Ca2+ stimulated the enzyme production. The activity of extracellular thiaminase I ranged between 1.29 and 1.33 U/ml medium.
The purification and immobilization of Penicillium notatum β‐galactosidase
Authors: Rogalski J. , Łobarzewski J.
Published: December 2004

Penicillium notatum No. 1 as a producer of β‐galactosidase was cultivated in a 5–1 fermenter. Various methods of protein isolation and concentration from the culture fluid were optimized. Then the conditions of β‐galactosidase purification using an affinity chromatographic technique were established. The purified enzyme was immobilized on a controlled porous glass (CPG). The optimum temperature and pH values of the native and immobilized forms of β‐galactosidase were determined as 50°C and 30–50°C as well as pH 3 and pH 3–5, respectively.
Cultivation of a filamentous mould in an airlift bioreactor
Authors: Gavrilescu M. , Roman R.‐V.
Published: December 2004

Cephalosporin C biosynthesis was investigated in a pilot‐plant external‐loop airlift bioreactor for evaluating the capacity of this bioreactor to surpass the problems which arise from the morphology of the mould and the rheology of the broth.

Some of the results were compared with those obtained in a stirred tank bioreactor.

The dilution and the use of static mixers was necessary to overcome the effects of the high viscosities. The oxygen transfer rate represented 84% of that in the stirred bioreactor, but the efficiency of the power utilization was higher.

The specific productivity of Cephalosporin C is comparable to that obtained in the stirred tank bioreactor, but the average specific power consumption was found to be 2/3 of that in the stirred vessel.
Evolutionary biotechnology – theory, facts and perspectives
Authors: Schuster P.
Published: December 2004

Molecular evolution has recently been applied in biotechnology which consist of the development of evolutionary strategies in the design of biopolymers with predefined properties and functions. At the heart of this new technology are the in vitro replication and random synthesis of RNA or DNA molecules, producing large libraries of genotypes that are subjected to selection techniques following DARWIN's principle. By means of these evolutionary methods, RNA molecules were derived which specifically bind to predefined target molecules. Ribozymes with new catalytic functions were obtained as well as RNA molecules that are resistant to cleavage by specific RNases. In addition, the catalytic specificities of group I introns, a special class of ribozymes, were modified by variation and selection.

Efficient applications of molecular evolution to problems in biotechnology require a fundamental and detailed understanding of the evolutionary process. Two basic questions are of primary importance: (i) How can evolutionary methods be successful as the numbers of possible genotypes are so large that the chance of obtaining a particular sequence by random processes is practically zero, and (ii) how can populations avoid being caught in evolutionary traps corresponding to local fitness optima? This review is therefore concerned with an abridged account of the theory of molecular evolution, as well as its application to biotechnology. We add a brief discussion of new techniques for the massively parallel handling and screening of very small probes as is required for the spatial separation and selection of genotypes. Finally, some imminent prospects concerning the evolutionary design of biopolymers are presented.
Immobilization of glucose oxidase and peroxidase to a urea derivative of granulated microcrystallized cellulose
Authors: Ivanov I. P.
Published: December 2004

Glucose oxidase and peroxidase were immobilized individually to a urea derivative of granulated microcrystallized cellulose activated by formaldehyde. The catalytic properties of the immobilized enzymes were studied and compared to those of the soluble enzymes. The immobilized glucose oxidase and peroxidase were used for the manual determination of the concentration of glucose in sera. The developed method is characterized by high analytical reliability and comparatively low cost. The results correlated well with those obtained by using a BECKMAN glucoanalyzer, utilizing soluble glucose oxidase.
Cloning and expression of the porA gene of the Neisseria meningitidis strain B : 4 : P1.15 in Escherichia coli. Preliminary characterization of the recombinant polypeptide
Authors: Guillen G. , Alvarez A. , Niebla O. , Silva R. , Gonzalez S. , Musacchio A. , Martin A. , Delgado M. , Herrera L.
Published: December 2004

The gene coding for the class 1 outer membrane protein from the Neisseria meningitidis strain B385 (B : 4 : P1.15) was isolated by the Polymerase Chain Reaction (PCR) and cloned into the Sma I cut M13mp 18 vector. Then, a Xba I restriction site was created by using an oligonucleotide‐directed in vitro mutagenesis system at the start of the coding fragment. In order to express the protein, this fragment was fused to 180 base pairs corresponding to 60 amino acids from the N terminus of interleukin‐2 under the control of the tryptophan promoter (Ptrp). The expression was confirmed by Western‐blotting where the recombinant protein (PILM28) was detected by bactericidal monoclonal antibodies (MABs). The recombinant polypeptide was partially purified and used to elicit murine antibodies, able to recognize the meningococcal class 1 subtype 15.
The use of a thermotolerant fermentative Kluyveromyces marxianus IMB3 yeast strain for ethanol production
Authors: Banat I. M. , Singh D. , Marchant R.
Published: December 2004

An investigation was carried out on the growth and ethanol production of a novel thermotolerant ethanol‐producing Kluyveromyces marxianus IMB3 yeast strain. It grew aerobically on glucose, lactose, cellobiose, xylose and whey permeate and fermentad all the above carbon sources to ethanol at 45°C. This strain was capable of growing under anaerobic chemostat fermentation conditions at 45°C and a dilution rate of 0.15 h−1 and produced ≤ 0.9 g/l biomass and 1.8% (v/v) ethanol. An increase in biomass (up to 10.0 g/l) and ethanol (up to 4.3% v/v at 45°C and 7.7% v/v at 40°C) were achieved by applying a continuous two‐stage fermentation in sequence (one aerobic and one anaerobic stage) or a two‐stage anaerobic fermentation with cell recycling. Potential applications, involving alcohol production systems, for use in dairy and wood related industries, were discussed.
Heavy metal sorption by microalgae
Authors: Sandau E. , Sandau P. , Pulz O.
Published: December 2004

Viable microalgae are known to be able to accumulate heavy metals (bioaccumulation). Against a background of the increasing environmental risks caused by heavy metals, the microalgae Chlorella vulgaris and Spirulina platensis and their potential for the biological removal of heavy metals from aqueous solutions were taken as an example for investigation. Small‐scale cultivation tests (50 1) with Cd‐resistant cells of Chlorella vulgaris have shown that approx. 40% of the added 10 mg Cd/l was removed from the solution within seven days. At this heavy metal concentration sensitive cells died.

Non‐viable microalgae are able to eliminate heavy metal ions in a short time by biosorption in uncomplicated systems, without any toxicity problems. Compared with original biomasses, the sorption capacity of microalgal by‐products changes only insignificantly. Their low price makes them economical.
Modelling the stability of the pBR322 plasmid derivative pBB210 in Escherichia coli TG1 under non‐selective and selective conditions
Authors: Löser C. , Ray P.
Published: December 2004

A mathematical model has been developed to describe the stability behaviour of the pBR322 plasmid derivative pBB210 with the β‐lactamase gene and the human interferon‐α1 gene in Escherichia coli TG1 under non‐selective, selective and modified selective conditions in a chemostat. The model was formulated on the basis of experimental investigations. It includes the interaction between β‐lactam antibiotics (ampicillin and sulbactam) and cells (with and without plasmids), in particular the correlation between the growth rate of plasmid‐free cells and ampicillin concentration in the medium; ampicillin transport into the periplasm of the plasmid‐bearing cells; ampicillin degradation in the periplasm by by plasmid‐encoded β‐lactamase and the inhibition of the latter by sulbactam.

The results obtained by the simulation of chemostat cultivations under various conditions and by steady state analyses are closely related to the results of experiments. Under non‐selective conditions, the fraction of plasmid‐bearing cells was approaching zero. Under selective and modified selective conditions, a coexistence between plasmid‐free and plasmid‐bearing cells was reached at steady state. Under these conditions, the steady state fraction of plasmid‐bearing cells was proportional to the ampicillin concentration in the feed and inversely proportional to the cell concentration in the chemostat. During high‐density cultivation, a large amount of ampicillin is necessary to suppress plasmid‐free cells. Even small concentrations of the β‐lactamase inhibitor sulbactam in the feed increased the steady state fraction of plasmid‐bearing cells (from 17.2% to 99.6% at sulbactam‐Na concentrations of 0 to 5 mg/l).
Degradation of sugar cane bagasse by several white‐rot fungi
Authors: Breccia J. D. , Siñeriz F. , Bettucci L. , Piaggio M.
Published: December 2004

Forty‐two white‐rot fungi isolated in South America were incubated with long fibre sugar cane bagasse (LFB). The residual composition of LFB was determined after white‐rot decay at 30 and 60 days. The ratio of residual lignin to residual lignin to residual cellulose (RL/RC) of untreated material (LFB) was 0.48. After white‐rot‐decay, the residual material with lower RL/RC ratios indicated that mainly lignin was degraded. In only 30 days,Phlebiasp. MVHC 5535,Atheliasp. MVHC 5509 andSpongipellis pachyodonMVHC 5019 caused a decrease in the RL/RC ratio to 0.36, 0.37 and 0.38, respectively, while it took 60 days forGanoderma applanatumMVHC 5347,Hyphodontiasp. MVHC 5544,Panus tigrinusMVHC 5400,Stereumsp. MVHC 5113,Phellinus punctatusMVHC 5346 and MVHC 6388 to reach a ratio lower than 0.40. No correlation was found between the amount of some ligninolytic enzymes secreted and the residual composition of bagasse after white‐rot fungi fermentation. Most of the fungal strains caused an increase in the relative amount of residual cellulose, indicating that hemicellulose was the preferred energy source.
α‐Galactosidase in immobilized cells of Papaver somniferum L.
Authors: Stano J. , Nemec P. , Kovács P. , Kákoniová D. , Lišková D. , Neubert K.
Published: December 2004

A poppy cell suspension culture was permeabilized by Tween 80 and immobilized by glutaraldehyde. The α‐Galactosidase in these cells showed an optimum pH level at 5.2 and an optimum temperature at 70 °C. Enzyme hydrolysis was linear for 3 h, reaching 86% conversion. A very good level of storage stability was achieved when using dry catalyst and immobilized cells in 0.15 M NaCl solution (with the addition of chloramphenicol, [1‐methyldodecy1)‐dimethylamin‐4‐oxide (ATDNO), chlortetracycline hydrochloride (CLCTC)] or by freezing them in 0.15 M NaCl solution.
Lipase‐catalyzed kinetic resolution of (R,S)‐1‐phenylethyl propionate in an enzyme membrane reactor
Authors: Ceynowa J. , Koter I.
Published: December 2004

Enzymatic stereoselective hydrolysis of (R,S)‐1‐phenylethyl propionate was performed in a stirred tank and in a biphasic enzyme membrane reactor. Lipase from Pseudomonas sp. was proved to be a good enantioselective catalyst for this reaction. The enzyme was covalently immobilized in a porous polyamide membrane (flat sheet as well as hollow‐fibres) via glutaraldehyde. An influence of membrane hydrophobicity on reactor performance was observed. Initial lipase activity and productivity in the processes were equal to 1.05 × 10−4, 1.3 × 10−5 and 1.0 × 10−5 mole/(h × mg of enzyme) in the case of native lipase, in the aromatic polyamide hydrophobic membrane reactor and in the hydrophilic polyamide‐6 membrane reactor, respectively. The influence of some factors such as temperature, pH, buffer concentration, initial substrate concentration and addition of β‐cyclodextrin derivatives on reaction rate and enantioselectivity was investigated and discussed. In the enzyme membrane reactor both organic and aqueous phases circulated countercurrently on both sides of the membrane. At a conversion degree of under 55–60%, pure enantiomer of the remaining ester (i.e. > 98%) was obtained.
Methods based on artificial intelligence, for controlling biotechnological processes. Monitoring of the concentration of dissolved oxygen (part III)
Authors: Sarkisjants L. , Kristapsons M.
Published: December 2004

A real‐time artificial intelligence method for controlling the concentration of dissolved oxygen is proposed.

Two projection versions of algorithms are considered in this paper. The versions vary in structure of the intelligent agents. One of the agents represents an automaton of expedient behaviour, the structure of the other consists of two automata which behave expediently in a complicated random medium.

The first algorithm holds a check on a trend of change in values. The second version of the algorithm takes into account both the trend of change in the values and the speed of change in the values.

Simulation studies show that expedient behaviour of the automata in the random medium for the control of dissolved oxygen concentration can bring about a good performance.
Growth kinetics of the 4‐nitrophenol degrading strain Pseudomonas putida PNP1
Authors: Löser C. , Oubelli M. Ait , Hertel T.
Published: December 2004

A 4‐nitrophenol degrading strain PNP1 isolated from the El‐Harrach River near Algiers (Algeria) was studied with respect to its growth behaviour. According to the morphological and biochemical characteristics this strain was assigned to Pseudomonas putida. Besides 4‐nitrophenol, the strain also used 1,2‐ and 1,4‐dihydroxybenzene, benzoate, 4‐hydroxybenzoate and 3,4‐dihydroxybenzoate as sources of carbon and energy, degrading them exclusively via the ortho pathway. Pseudomonas putida PNP1 degrades 4‐nitrophenol through a purely oxidative pathway with release of the nitro group as nitrite. During cultivation with 4‐nitrophenol in ammonium‐containing mineral medium, the strain PNP1 grew optimally at pH 7 and at a temperature between 30 and 35°C and showed stoichiometric nitrite release (at pH 7 and 30°C MONOD model parameters μmax = 0.615 h−1 and KS = 0.145 mg/l). A phenomenological model for the description of growth inhibition at high 4‐nitrophenol concentrations was derived (below 400 mg/l only weak inhibition and at 600 mg/l acute toxicity). In ammonium‐free medium, the maximum specific growth rate was reduced to 0.318 h−1 and part of the 4‐nitrophenol‐N was used as the nitrogen source (32% N in biomass and 68% N in nitrite). The yield coefficients of strain PNP1 were smaller in ammonium‐free than in ammonium‐containing medium (e.g. with 4‐nitrophenol YX/S = 0.305 g/g compared to 0.350 g/g), which can be explained by the energy expense for the assimilatory nitrite reduction in the biosynthesis of N‐containing cellular compounds. But the oxygen consumption was only slightly influenced by the ammonium content of the cultivation medium (e.g. with 4‐nitrophenol YO/S = 1.005 g/g compared to 0.954 g/g).
Enzymatic decrease in the phenolic content of canola meal using concentrated aqueous or aqueous/hexane slurries
Authors: Lacki K. , Duvnjak Z.
Published: December 2004

An enzymatic process to decrease the phenolic content in canola meal was investigated. The new method was based on the addition of an enzyme preparation from the white‐rot fungus Trametes versicolor to concentrated meal‐buffer slurries. This approach eliminated the extraction of the valuable meal components such as proteins and carbohydrates. Two systems were considered: (i) slurries with canola meal concentrations higher than 33% [w/v]; (ii) slurries with canola meal concentrations equal to or less than 12.5% [w/v] with n‐hexane as the main component of the continuous phase.

The concentration of sinapic acid esters decreased by 99% after a 1.5, 2 and 3 hour long treatment of the meal with an initial moisture content of 75% at 90°C, 70°C and 50°C, respectively. The process was carried out at temperaturs as high as 110°C. Both the enzyme and the moisture concentrations influenced the enzymatic process and their action was coupled. The concentration of oxygen strongly affected the process.

The enzymatic process was able to be carried out in the presence of hexane as the main component of the continuous phase. The optimum temperature for such a process was 30–40°C, At 30°C, after 1 h of treatment, the meal phenolic content was decreased by 97%. The water uptake by the meal was diminished in the presence of hexane.
The extractive purification of peroxidase from plant raw materials in aqueous two‐phase systems
Authors: Miranda M. V. , Fernández‐lahore H. M. , Cascone Osvaldo , Dobrecky J.
Published: December 2004

The extractive purification of peroxidase from Armoracia rusticana roots and Glycine max seed coats in temperature‐induced and affinity microsphere‐containing aqueous two‐phase systems was stuied. The extractive purification of peroxidase from Glycine max seed coats was carried out in a temperature‐induced aqueous two‐phase system formed by Triton X‐45, Triton X‐100 and sodium acetate at pH 5.5 A 99% yield with a 6‐fold purification factor was obtained. When the clear top phase was subjected to concanavalin‐A affinity chromatography, the purification factor rose to 41 and the yield dropped to 28%.

A two‐step purification process for peroxidase from Armoracia rusticana roots was developed by adding concanavalin‐A affinity microspheres to a PEG/phosphate aqueous two‐phase system. The method allows a 60% recovery of high purity peroxidase (1,860 guaiacol units per mg). A lower recovery rate and degree of purification of this enzyme was achieved after temperature‐induced aqueous two‐phase partition or acetone precipitation and concanavalin‐A affinity column chromatography.
The effect of chemical treatment of stainless steel wire surfaces on Zymomonas mobilis cell attachment and product synthesis
Authors: Karsakevich A. , Ventina E. , Vina I. , Bekers M. , Gonta S. , Linde R. , Kaminska E.
Published: December 2004

The attachment, growth and product synthesis of non‐flocculating Zymomonas mobilis cell, fixed in stainless steel wire spheres (WS), were investigated. The carrier surface was activated by treatment with titanium (IV) chloride (TiCl4) and γ‐aminopropyltriethoxysilane (AS) in an attempt to raise the efficiency in the immobilization of the cells. System productivity for ethanol and levan production, using cells immobilized on a modified stainless steel in the batch fermentation of a sucrose medium, rose as a result of increased biomass compared to the productivity of cells fixed on untreated (control) metal surfaces. Stabilized ethanol synthesis was demonstrated in the course of four cycles (each cycle 48 h) of repeated fermentations with a stainless steel carrier treated with AS, and three cycles when TiCl4 was used. Levan synthesis decreased after three cycles with cells immobilized on a silanized surface. System productivity for ethanol and levan production after the fourth cycle in experiments with TiCl4‐activated, silanized and unmodified carriers were Qeth = 1.01, 1.06 and 0.27 g/l × h; Qlev = 0.32, 0.29 and 0.12 g/l × h, respectively. However, the specific productivity of biomass for product synthesis was higher in fermentation systems with untreated stainless steel surfaces, probably due to some loss of physiological activity of cells attached to a modified carrier. Investigations of throughly washed activated stainless steel wire surfaces, by scanning electron microscopy after immobilization, showed significant attachment of cells to the carriers. A polymer layer covered the wire surface treated with TiCl4 after fermentations. This may be explained as the binding of extracellular polysaccharide, such as the fructose‐polymer levan and yeast extract components, to the modified support via chelation. After four fermentations, craters and holes in the polymer layer were evident, probably as a result of CO2 formation. A small number of cells appeared on this layer. In view of the good ethanol formation during all fermentation cycles, it is probably that active Z. mobilis cells remained under the polymer layer. Wire treatment with AS resulted in the formation of long filamentous cells during fermentation and some disturbance of cellular fission. This may be partly explained by strong electrostatic interactions between the positively charged carrier surface and the predominately negatively charged surface of Z mobilis cells. However, this did not significantly affect other cellular functions. The surface of the wire treated with AG was practically without a polymer layer.
Studies on whey fermentation using lactic acid bacteria L. acidophilus and L. bulgaricus
Authors: Skudra L. , Blija A. , Sturmović E. , Dukaļska L. , Áboltiņš A. , K´rkliņa D.
Published: December 2004

The fermentation process of acid curd whey using pure cultures of L. bulgaricus and L. acidophilus was investigated. The influence of the starter culture amount on the acidification rate in the fermentation was specified, the biological value of fermented and fermented‐ammoniated curd whey was determined, and the ability of fermented whey to prevent the injurious effect of Bac. mesenthericus on the wheat bread quality was examined.

Acid curd whey was fermented up to a titratable acidity of 19.8–21.6 g lactic acid/kg whey using L. acidophylus and L. bulgaricus. Mathematical equations were developed on the basis of experimental data to calculate the titratable acidity (A) as a functionof fermentation time (τ) and temperature (t). Fermentation and fermentation‐ammoniation processes increase the biological value of whey (the content of the vitamins B1, B2, B6, PP and the free amino acids increase). A new dry fodder BIOLAKTS was developed from fermented curd whey and was recommended for use in veterinary medicine. The fermentation‐ammoniation process of curd whey was carried out by adding calculated amounts of non‐protein nitrogen NH4OH to increase the total protein equivalent and to achieve mutual proportions of protein and lactose 1:1.4, as in skimmed milk. Fermented‐ammoniated curd whey was used to obtain a skimmed milk substitute. A dry flour lactic acid concentrate (FLC) was created as a mixture of high quality wheat flour and evaporated fermented whey in established ratios. As our experiments prove, it can be used as an additive in bread‐making to prevent the spoiling of wheat bread by Bac. mesenthericus.
Preparation and some properties of multinucleate cells of Saccharomyces cervisiae after colchicine treatment
Authors: Toyama H. , Toyama N.
Published: December 2004

For the purpose of forming cells possessing more than three nuclei and of determining the factors inducing multinucleation, cells of Saccharomyces cerevisiae were treated with 0, 0.3, 0.5, and 1.0% [w/v] colchicine solution, with and without shaking. When the cells were treated with 1.0% [w/v] colchicine solution, the number of cells containing two to eight nuclei was the largest. The multinucleate cells could grow on potato dextrose agar medium and their multinucleate nature did not disappear for at least three generations. This means that such cells are genetically stable. The proliferation rate of the multinucleate cells was not superior to that of the original strain. However, by monitoring the weight loss of the flask, it was possible to indirectly estimate the increase in the alcohol production of the multinucleate cell. It was concluded that the shaking treatment and higher colchicine concentrations contributed to multinucleation.
Mixed‐solid substrate fermentation. A novel process for enhanced lipase production by Candida rugosa
Authors: Benjamin S. , Pandey A.
Published: December 2004

Candida rugosa was cultivated in a mixed‐solid substrate containing coconut oil cake (COC) and fine and coarse wheat bran (1:1:1) with an initial water activity (aw) of 0.92. The substrate was modified by adding a mineral solution (5%), corn steep liquor (6%), maltose (2%), peptone (3%), olive oil (10%), gum arabic (0.4%), different fatty acids (0.3%) and Tweens (0.5%). Fermentation in a column fermenter significantly improved the lipase yield to 118.2 Units per gram of dry fermented substrate [U/gds] at 72 h. This result was obtained 24 hours earlier than in our former studies (87.76 U/gds at 96 h) in COC, and the yield showed a 38% increase. Growth was measured indirectly by determining the glucosamine content in the cell wall of the yeast contained in the fermented matter, after its hydrolysis.
Optimization of the growth parameters of Aspergillus foetidus
Authors: Kara A. , Bozdemir T. Ö.
Published: December 2004

The batch production of gluconic acid in the presence of glucose, sucrose and molasses was investigated using free mycelia of Aspergillus foetidus NRRL 337 in shake flasks. Eight growth parameters were chosen as independent variables. The temperature, pH, substrate type and initial concentrations, inoculum percentage and shake rate directly affected the specific microorganism growth and gluconic acid production rates. The optimum temperature and initial pH values were found to be 33°C and five to six, respectively. The maximum specific growth and gluconic acid production rates were established as 57 g/dm3 of glucose, 75 g/dm3 of sucrose and 150 g/dm3 of molasses. The optimum values of the shake rate, inoculum percentage and initial ammonium nitrate concentration were determined as 100 1/min, 0.5% and 1.5 g/dm3, respectively. The maximum gluconic acid concentrations corresponding to these initial substrate concentrations were observed to be 8.3 g/dm3, 17.4 g/dm3 37.0 g/dm3, respectively. The optimum specific microbial growth and gluconic acid production rates were found as 0.0145 1/h and 0.0375 g/g × h, respectively, for the fermentation conditions of SGo = 57 g/dm3, T = 28°C, initial pH = 6.5, N = 84 1/min, A = 0.5 g/dm3 and I = 0.5%.
Ligninolytic enzymes from corncob cultures of Phanerochaete chrysosporium under semi‐solid‐state conditions
Authors: Couto S. Rodríguez , Longo M. A. , Cameselle C. , Sanromán A.
Published: December 2004

The effects of adding some inducers of lignolytic activity to semi‐solid‐state cultures of Phanerochaete chrysosporium BKM‐F‐1767 (ATCC 24725) were investigated. The inducers assayed were veratryl alcohol and solid manganese (IV) oxide. The microorganism was cultured on corncob, which functioned both as physical support and source of nutrients.

Supplementing the cultures with veratryl alcohol created the situation where manganese‐dependent peroxidase (MnP) and lignin peroxidase (LiP) activities of approximately 1,500 U/l and 200 U/l, respectively, could be attained. These activities were considerably higher than those obtained in the reference cultures (about 5 and 4‐fold).

In the same way, the addition of manganese (IV) oxide led to MnP and LiP activity levels of about 2,000 U/l and 300 U/l, respectively. These activities were also notably above (about 6 and 5‐fold, respectively) those achieved in the reference cultures.

Moreover, laccase activity (around 200 U/l) was only detected in veratryl alcohol or manganese (IV) oxide supplemented cultures.
Selective recovery of xylanase from Penicillium janthinellum using BDBAC reversed micelles
Authors: Rodrigues E. M. , Milagres A. M. F. , Pessoa A.
Published: December 2004

A xylanase was removed from crude extract of the fungus Penicillium janthinellum under optimized conditions: 0.10M phosphate buffer, pH 7.0, 0.2 M BDBAC (N‐benzyl‐N‐dodeceyl‐N‐bis (2‐hydroxyethyl) ammonium chloride), 7.5% hexanole, 30°C and an agitation time of 1 minute. At 1.42 mg per ml protein concentration, 73% of the xylanase activity was recovered and a 7‐fold enrichment factor was obtained. The enzyme had a molecular weight (MW) of 20.1 kDa and the isoelectric point (PI) revealed the presence of two protein bands with a PI of 6.0 and 6.5. The optimum pH and optimum temperature were 4.2 and 50°C, respectively. The low pH differential between the aqueous medium and the protein PI seemed to influence the xylanase transportation into the reversed micelles.
Morphoregulatory effect of plant growth regulators on Hypericum perforatum L. Seedlings
Authors: Čellárová E. , Kimáková K.
Published: December 2004

The morphogenetic response of Hypericum perforatum seedlings to different auxin and cytokinin concentrations was studied. A stimulation of the concentration‐dependent rooting ability was observed under the influence of indole‐3‐acetic acid and indole‐3‐butyric acid. Rooting was not enhanced by the effects of 2,4‐dichlorophenoxyacetic acid and 1‐naphtaleneacetic acid. Differentiated roots were isolated and cultured in liquid media with the same combination of growth‐promoting auxins. Chromosome counts in root tip cells after long‐term cultivation indicated a high degree of chromosomal instability. Multiple shoot formation occurred under the influence of 6‐benzylaminopurine and kinetin. Adenine and 6‐(γ,γ‐dimethylallylamino)‐purine did not stimulate shoot differentiation. No differences in the morphogenetic response to auxins and cytokinis were detected between diploid and tetrapoloid plants.
Influence of a pulsed electric field on the spores and oxygen consumption ofAspergillus nigerand its citric acid production
Authors: Fiedurek J.
Published: December 2004

Spores ofAspergillus nigerwere exposed to a pulsed electric field. After treatment by the electric field, the viability of the conidia ofA. nigervaried depending on the field strength, pulse width and frequency. In all cases, these parameters reduced the viability rate of the conidia from 2.0 × 107to a range from 6.2 × 106to 8.5 × 106spores/ml (3.1 to 42.6%). After pulse treatment, the conidia were used as the inoculum for citric acid fermentation in shake flasks. The highest increase in citric acid yield (about 1.4‐fold) was reached at a field strength of 2.85 kV/cm, a frequency of 1 Hz and a pulse width of 1 ms. When the parameters of the electric field increased there were important changes in the respiration rate of theAspergillus nigermycelium (48‐h‐old) after electric shock treatment. The highest consumption of dissolved oxygen (22.9%) in the medium byAspergillus nigermycelium was observed at an electric field strength of 2.85 kV/cm, a 1 Hz frequency, a pulse width of 1 ms and a 1‐min exposure period. It seems that an electric‐field stimulation of the conidia prior to inoculation may offer an important method of improving the efficiency of citric acid. The treatment of the conidia is both simple from the technical point of view and extremely rapid.
The development of biotechnology in environmental processes
Authors: Rehm H.‐J.
Published: December 2004

The application of biotechnology in environmental processes is an enormous subject that could remain the topic of a university lecture course for many years. For this reason I wish to limit my lecture to a few examples and to attempt to sketch out particularly promising opportunities for future development.
Hydrolysis of lactose in whey permeate by immobilized β‐galactosidase from Penicillium notatum
Authors: Szczodrak J.
Published: December 2004

A new low‐cost β‐galactosidase (lactase) preparation for whey permeate saccharification was developed and characterized. A biocatalyst with a lactase activity of 10 U/mg, a low transgalactosylase activity and a protein content of 0.22 mg protein/mg was obtained from a fermenter culture of the fungus Penicillium notatum. Factors influencing the enzymatic hydrolysis of lactose, such as reaction time, pH, temperature and enzyme and substrate concentration were standardized to maximize sugar yield from whey permeate. Thus, a 98.1% conversion of 5% lactose in whey permeate to sweet (glucose‐galactose) syrup was reached in 48 h using 650 β‐galactosidase units/g hydrolyzed substrate. After the immobilization of the acid β‐galactosidase from Penicillium notatum on silanized porous glass modified by glutaraldehyde binding, more than 90% of the activity was retained. The marked shifts in the pH value (from 4.0 to 5.0) and optimum temperatures (from 50°C to 60°C) of the solid‐phase enzyme were observed and discussed. The immobilized preparation showed high catalytic activity and stability at wider pH and temperature ranges than those of the free enzyme, and under the best operating conditions (lactose, 5%; β‐galactosidase, 610–650 U/g lactose; pH 5.0; temperature 55°C), a high efficiency of lactose saccharification (84–88%) in whey permeate was achieved when lactolysis was performed both in a batch process and in a recycling packed‐bed bioreactor. It seems that the promising results obtained during the assays performed on a laboratory scale make this immobilizate a new and very viable preparation of β‐galactosidase for application in the processing of whey and whey permeates.
A model for biopigment formation by Serratia marcescens biovar A2/6 in batch cultures containing lactic acid and beef extract
Authors: Hardjito L. , Bley Th.
Published: December 2004

Serratia marcescens biovar A2/A6 is able to produce a red pigment as a secondary metabolite which has antimicrobial activity. This paper describes its growth and biopigment formation in batch cultures, in media containing different concentrations of lactic acid and beef extract as carbon and nitrogen sources, respectively. An unstructured model has also been developed to describe its growth, lactic acid uptake and biopigment formation. The comparison of simulated and experimental data shows that the proposed model predicts reasonably well the system behaviour over a range of conditions.
Innovative use ofThiobacillus ferrooxidansfor the biological machining of metals
Authors: Ting Y. P. , Kumar A. Senthil , Rahman M. , Chia B. K.
Published: December 2004

Preliminary results on the novel use of the bacteriumThiobacillus ferrooxidans(ATCCJ 3598 and ATCC33020) for the micro‐machining (orbiomachinig) of metals are reported. Biomachning is a controlled microbiological process to selectively form microstrucutures on a metal work‐piece by metal removal (or dissolution) using microorganisms. Applying copper and mild steel as work‐pieces, it was shown that the mass removed increased proportionately with machining time. In another experiment, the work‐pieces were coated with organic photo‐resistive materials to mask (i.e. protect) certain regions of the metlas, thereby defining the microstructure to be formed. The unmasked regions were successfully biomachined; the final machined profile was shown to be similar to the coating image on the original metal. Although biomachining proceeded at a slower rate than chemical machining, the undesired leaching of the metal in the region under the masked area (termed undercutting) was not as severely encountered when compared with the latter. This work demonstrates the potential use of microorganisms for the biomachining of metals. As a “green process”, the innovative use ofT. ferrooxidansfor the micro‐machining of metals opens up the possibility of biomachining as an alternative to conventional metal processing.