bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lipase‐catalyzed kinetic resolution of (R,S)‐1‐phenylethyl propionate in an enzyme membrane reactor
Authors: Ceynowa J. , Koter I. 
Published: December 2004

AbstractEnzymatic 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

AbstractA 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

AbstractA 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

AbstractAn 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractFor 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

AbstractCandida 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractSpores 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.
Hydrolysis of lactose in whey permeate by immobilized β‐galactosidase from Penicillium notatum
Authors: Szczodrak J. 
Published: December 2004

AbstractA 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

AbstractSerratia 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

AbstractPreliminary 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.