Showing papers in "Biotechnology Letters in 1991"
TL;DR: Aqueous Solutions of N-carboxymethylchitosan suppressed both growth and aflatoxin production by Aspergillusflavus and A.parasiticus in submerged culture and NCMC-treated cultures showed marked reduction of a Flatoxin production and fungal growth.
Abstract: Aqueous Solutions of N-carboxymethylchitosan (NCMC) suppressed both growth and aflatoxin production byAspergillusflavus andA.parasiticus in submerged culture (Adye and Mateles A&M). Test media were amended with various concentrations of zinc (15, 30, 45, 60 uM), and NCMC solution (0.62 uM). After 8 days incubation NCMC-treated cultures showed marked reduction of aflatoxin production and fungal growth. Enhanced levels of zinc did not overcome the NCMC-mediated inhibition of fungal growth or aflatoxin production.
203 citations
TL;DR: The Candida guillermondii strain did not convert glucose, mannose and galactose into their corresponding polyols but only into ethanol and cell mass and fermentation of arabinose lead to the formation of arabitol.
Abstract: The ability ofCandida guillermondii to produce xylitol from xylose and to ferment individual non xylose hemicellulosic derived sugars was investigated in microaerobic conditions. Xylose was converted into xylitol with a yield of 0,63 g/g and ethanol was produced in negligible amounts. The strain did not convert glucose, mannose and galactose into their corresponding polyols but only into ethanol and cell mass. By contrast, fermentation of arabinose lead to the formation of arabitol. On D-xylose medium,Candida guillermondii exhibited high yield and rate of xylitol production when the initial sugar concentration exceeded 110 g/l. A final xylitol concentration of 221 g/l was obtained from 300 g/l D-xylose with a yield of 82,6% of theoretical and an average specific rate of 0,19 g/g.h.
126 citations
TL;DR: The influence of the immobilization procedure on the synthetic activity of the derivatives was considered, and solvent hydrophobicity and water content in the biphasic system influenced both enzyme stability and equilibrium displacements.
Abstract: Mucor miehei lipase has been adsorbed on Celite and covalently bound to nylon. The obtained derivatives have been studied regarding their ability for synthetize several flavouring esters in biphasic aqueous/organic media. The influence of the immobilization procedure on the synthetic activity of the derivatives was considered. Solvent hydrophobicity and water content in the biphasic system influenced both enzyme stability and equilibrium displacements. In this way, solvents with log P>3.5 and less than 1% water were optimal. It was important to consider pH effects on enzyme microenvironment when using acidic substrates. Optimum temperature and reuse of the catalyst were also checked.
111 citations
TL;DR: In this article, the removal of zinc and cadmium from homosphaera cells was investigated with sodium alginate immobilized cells, and the results showed that the metal removal achieved values near 100%.
Abstract: Cadmium and zinc biosorption, alone or in combination, was investigated with sodium alginate immobilizedChlorella homosphaera cells. Concentrations ranging from 20.0 to 41.0mg/l cadmium, 75.0 and 720.0mg/l zinc were tested and, in all cases, the metal removal achieved values near 100%. When these metals were put in combination a decrease in the rate of absorption was detected. Gold was also tested in the immobilized system and 90% of the initial metal added was recovered in a solution containing 213.0mg/l of the metal, the alginic matrix being responsible for 40% gold uptake.
109 citations
TL;DR: The highest pullulan yield was achieved at decreased constant DO in connection with decreased shear rate, and biomass production was not affected.
Abstract: Experiments were carried out withA. pullulans (ATCC 9348) at constant dissolved oxygen concentration (DO=100 and 50% related to air saturation at 1 bar) and at constant stirrer speeds (n=500 and 150 [min−1]). The highest pullulan yield was achieved at decreased constant DO in connection with decreased shear rate. Biomass production was not affected.
96 citations
TL;DR: Defective interfering particles, present within a high passage inoculum of Autographa californica nuclear polyhedrosis virus (AcMNPV), interfered with recombinant β-galactosidase and infectious virus production in three insect cell lines.
Abstract: Defective interfering particles, present within a high passage inoculum ofAutographa californica nuclear polyhedrosis virus (AcMNPV), interfered with recombinant β-galactosidase and infectious virus production in three insect cell lines. These particles were Selected during serial passage, were missing large parts of the AcMNPV genome, and caused large reductions in β-galactosidase production at multiplicities of infection above 0.01 pfu/cell.
92 citations
TL;DR: Lignin peroxidases and lyophilized fungal culture were shown to have considerable potential for treating Kraft effluents and immobilized form all the studied systems exhibited an average value around of 30% polymer consumption and very little of depolymerization.
Abstract: Color removal from Kraft effluent by lignin peroxidase and horseradish peroxidase was compared. Free lignin peroxidase and horseradish peroxidase removed color from kraft effluent. Immobilization of lignin peroxidase type III, lyophilized fungal culture and horseradish peroxidase on CNBr-Sepharose 4B improved the decolorization by factor of 2.9, 4.5 and 2.6, respectively in 48 h. Lignin peroxidase type I was effective only in the immobilized form in decolorization. In general, the immobilized form all the studied systems exhibited an average value around of 30% polymer consumption and very little of depolymerization. Lignin peroxidases and lyophilized fungal culture were shown to have considerable potential for treating Kraft effluents.
91 citations
TL;DR: In this paper, a screening of 51 ligninolytic strains of fungi to examine their ability to decolorized phenolic industrial effluent was carried out, and the selection showed thatLentinus edodes (UEC-2019) strain removed 73% of colour in 5 days, without any additional carbon sources.
Abstract: A screening of 51 ligninolytic strains of fungi to examine their ability to decolorized phenolic industrial effluent was carried out. The selection showed thatLentinus edodes (UEC-2019) strain removed 73% of colour in 5 days, without any additional carbon sources. Under these conditions,L. edodes was more efficient than the knownPhanerochaete chrysosporium (BKM-F-1767) strain (e.g. COD reductions were 60% and 26%, respectively).
88 citations
TL;DR: Pseudomonas acidovorans DMR-11, capable of oxidizing dimethyl sulfide (DMS), was isolated from peat biofilter and was reversibly evolved in excess of DMSO.
Abstract: Pseudomonas acidovorans DMR-11, capable of oxidizing dimethyl sulfide (DMS), was isolated from peat biofilter. DMS as a sole carbon or energy source was not degraded, but it was co-degraded in the medium containing organic carbon sources. The removal rate of DMS in heat-treated glucose medium was 1.12×10−17 mole/h cell at 30 °C. Dimethyl sulfoxide (DMSO) was the only product of DMS oxidation and was formed stoichiometrically. DMS was reversibly evolved in excess of DMSO. The cell free extract of strain DMR-11 oxidized DMS in presence of NADPH.
84 citations
TL;DR: Fructose oleate undergoes continuous synthesis in a fixed catalyst bed reactor using an industrial fixed lipase and a yield of 83% is obtained by recycling the effluent 3 times.
Abstract: Fructose oleate undergoes continuous synthesis in a fixed catalyst bed reactor using an industrial fixed lipase. The effects of the time spent in the reactor, substrate concentration and effluent recycling are studied. A yield of 83% is obtained by recycling the effluent 3 times.
80 citations
TL;DR: Seven white-rot fungi were examined for the production of ligninase, manganese peroxidase and laccase, indicating that different species of fungi may employ different modes ofLignin metabolism.
Abstract: Seven white-rot fungi were examined for the production of ligninase, manganese peroxidase and laccase. All these enzymes were found inTrametes gibbosa andTrametes hirsuta. Only manganese peroxidase and laccase were produced byPycnoporus cinnabarinus,Coriolopsis polyzona,Stereum hirsutum,Dichomitus squalens andGanoderma valesiacum. All fungi decolorized Poly B-411 and Indulin AT plates with low-N medium. The differences in enzyme pattern indicate that different species of fungi may employ different modes of lignin metabolism.
TL;DR: In this article, a batch fermentor using Lactobacillus amylovorus was used to produce lactic acid from starch in 20 hours and 92.5 g/L of lactate in 39 hours.
Abstract: Fermentation production of lactic acid directly from starch was studied in a batch fermentor usingLactobacillus amylovorus. At an initial concentration of 120 g/L starch, 96.2 g/L of lactic acid was produced from liquefied starch in 20 hours while 92.5 g/L of lactate was produced from the raw starch in 39 hours. High initial glucose levels (100 g/L) in the medium inhibited the organism, unless it had been adapted by growing it in a low-glucose medium. The direct production of lactic acid from starch could reduce overall production costs significantly.
TL;DR: Because of the oxygen-vector properties of soybean oil, this oil is able to significantly increase the kL a of a bioreactor.
Abstract: The effect of soybean oil on the volumetric oxygen transfer coefficient during the cultivation ofAerobacter aerogenes cells is presented. For our aeration-agitation conditions (0.278 vvm and 500 rpm), it has been demonstrated that the use 19% (v/v) of soybean oil enabled a 1.85-fold increase of thekl a coefficient (calculated on a per liter aqueous phase basis). For smaller volumetric oil fractions,kL a increased linearly with the oil loading. Because of the oxygen-vector properties of soybean oil, this oil is able to significantly increase thekL a of a bioreactor.
TL;DR: To assess optimal saccharification performance, α-cellulose and dilute acid pretreated aspen (DAA) wood meal were subjected to various loadings of commercial cellulase and β-D-glucosidase preparations.
Abstract: To assess optimal saccharification performance, α-cellulose and dilute acid pretreated aspen (DAA) wood meal were subjected to various loadings of commercial cellulase and β-D-glucosidase preparations. Fifteen international filter paper units (IFPU)/g cellulose content and 30 IFPU/g cellulose content were required to digest 95% of the available cellulose in α-cellulose and pretreated aspen, respectively. The optimal supplementation ratios, based on Genencor GC 123 cellulase and β-D-glucosidase from Novo SP 188 for the α-cellulose and DAA digestions range from 0.25 to 0.5 and 0.12 to 0.25, respectively.
TL;DR: Several filamentous fungi were grown on solid state fermentation systems and selected for their highest yield in lipolytic activity, low protease levels and dairy flavor generation.
Abstract: Several filamentous fungi were grown on solid state fermentation systems and selected for their highest yield in lipolytic activity, low protease levels and dairy flavor generationP candidum,M miehei andP camembertii were the selected ones A comparison between kinetics in solid and submerged fermentation was performed usingP candidum, with the solid system giving the highest titers and a stable production
TL;DR: Extractive fermentation is shown to greatly improve the performance of Zymomonas mobilis in continuous culture during the conversion of concentrated substrates to ethanol, and it is also used to eliminate the oscillatory behavior often exhibited by Z. mobilIS in conventional fermentations.
Abstract: Extractive fermentation is shown to greatly improve the performance ofZymomonas mobilis in continuous culture during the conversion of concentrated substrates to ethanol, and it is also used to eliminate the oscillatory behavior often exhibited byZ. mobilis in conventional fermentations. An ethanol productivity of 15.6 g/Lh is achieved with the near-conversion of a 295 g/L glucose feed at a medium dilution rate of 0.11 h−1 and solvent dilution rate of 1.5 h−1. This is more than triple the productivity obtained during conventional fermentation of a 135 g/L glucose feed at the same medium dilution rate.
TL;DR: It was found that the equation (E1)T1=(E2)T2 correlated well with the experimental data obtained, and the effect of temperature on the enantiomeric ratio, E, was investigated in lipase catalysed hydrolysis and transesterification.
Abstract: In the field of enhancement of the enantiomeric excess, the effect of temperature on the enantiomeric ratio, E, was investigated in lipase catalysed hydrolysis and transesterification. It was found that the equation (E1)T1=(E2)T2 correlated well with the experimental data obtained.
TL;DR: The mechanism of this transformation is elucidated and the crucial role of the water still present in the enzyme preparation is shown, which is the hydrolysis of the dipalmitin followed by the isomerisation of the 2-monopalmitin into the 1-monoester.
Abstract: Enzyme catalyzed isomerisation of 1,2-dipalmitin into the 1,3-isomer is shown to occur with 1,3 regiospecific lipases The mechanism of this transformation is elucidated and the crucial role of the water still present in the enzyme preparation is shown Thus, the first step is the hydrolysis of the dipalmitin followed by the isomerisation of the 2-monopalmitin into the 1-monoester The last is then esterified into the 1,3-dipalmitin
TL;DR: Escherichia coli B (ATCC 11303) carrying the PET operon on plasmid pLOI 297 converted hemicellulose hydrolysate to ethanol at an efficiency of 94% theoretical maximum, which is 15% better than the highest efficiency reported for pentose utilizing yeasts in a comparable system.
Abstract: Escherichia coli B (ATCC 11303) carrying the PET operon on plasmid pLOI 297 converted hemicellulose hydrolysate to ethanol at an efficiency of 94% theoretical maximum, which is 15% better than the highest efficiency reported for pentose utilizing yeasts in a comparable system. Aspen prehydrolysate (APH), that had been produced by theBio-Hol Process using a Wenger extruder with SO2 as catalyst, was used as feedstock. The fermentation medium contained predominantly xylose (35g/L) with acetic acid present at about 6g/L. With the pH controlled at 7.0, this concentration of acetic acid was not inhibitory for growth or xylose fermentation. When the APH was fortified with nutrients (tryptone and yeast extract), the recombinant (inoculated at 0.5 g dry wt/L) converted 100% of the xylose to ethanol with a volumetric productivity of 0.29 g/L/hr. Overliming the APH with Ca(OH)2, followed by neutralization to pH 7 with sulphuric acid and removal of the insolubles, resulted in a 2-fold increase in productivity. The max. productivity was 0.76 g/L/hr. The productivity in Ca(OH)2-treated APH, fortified with only mineral salts, was 0.26 g/L/hr.
TL;DR: The temperature induced intracellular production of the fused protein SpA-βgal (protein A/β-galactosidase) withE.
Abstract: The temperature induced intracellular production of the fused protein SpA-βgal (protein A/β-galactosidase) withE. coli was compared in batch and fed batch culture. By introducing fed batch cultivation a final cell dry weight of 77.0 g/l was achieved, as compared to 16.4 g/l in batch cultivation. The concentration of SpA-βgal in the fed batch cultivation was very high, 19.2 g/l. This corresponded to 25% of the cell dry weight.
TL;DR: Yield of sophorose lipids characterized by TLC/FID was greatly influenced by yeast extract concentration in the shake flasks in contrary to highly aerated fermenter.
Abstract: Torulopsis bombicola produced sophorose lipids when growing on sucrose in similar yields as if growing on glucose. Besides yield the composition of sophorose lipids characterized by TLC/FID was greatly influenced by yeast extract concentration in the shake flasks in contrary to highly aerated fermenter.
TL;DR: Studies on sucrose hydrolysis with Zymomonas mobilis CP4 have revealed, via electrophoresis and zymogram staining, three enzymes that hydrolyze sucrose.
Abstract: Studies on sucrose hydrolysis withZymomonas mobilis CP4 have revealed, via electrophoresis and zymogram staining, three enzymes that hydrolyze sucrose. One electrophoretic band corresponds to the well characterized levansucrase, while the two remaining bands appear to be invertases (Inv A and Inv B). Inv A occurs intracellularly in CP4, while Inv B occurs in the supernatant as well as intracellularly.
TL;DR: High product yield (95% with respect to the carbohydrate donor) of octyl β-D-glucoside has been obtained in a two-phase system containing 5% of water and the enantioselection for the galactosyl transfer to the secondary hydroxyl group of propane-1,2-diol is higher than that found using β-galactosidase fromE.
Abstract: Crude homogenate of thermophilic archaebacteriumSulfolobus solfataricus, possessing a β-glycosidase, has been used to synthesize different alkyl β-D-glycosides starting from phenyl β-D-glucoside, phenyl β-D-galactoside and lactose as carbohydrate donors. High product yield (95% with respect to the carbohydrate donor) of octyl β-D-glucoside has been obtained in a two-phase system containing 5% of water. The enantioselection for the galactosyl transfer to the secondary hydroxyl group of propane-1,2-diol is higher than that found using β-galactosidase fromE. coli.
TL;DR: It was shown that the lipases fromMucor miehei andPseudomonas fluorescens do in fact not display the high 1(3)-specifities reported in the literature for these enzymes.
Abstract: A facile system was developed for the quantitative determination of lipase regioselectivities in organic solvents towards the 1(3)-position of glycerides. It was utilized for the measurement of the regioselectivities displayed by lipase preparations fromMucor miehei (Lipozyme™),Pseudomonas fluorescens andRhizopus delemar. It was shown that the lipases fromMucor miehei andPseudomonas fluorescens do in fact not display the high 1(3)-specifities reported in the literature for these enzymes.
TL;DR: The fermentation of D-xylose by Candida parapsilosis was studied in continuous cultures and xylitol formation seems to be directly coupled to growth of biomass and strongly influenced by oxygen consumption.
Abstract: The fermentation of D-xylose byCandida parapsilosis was studied in continuous cultures. From the results obtained, xylitol formation seems to be directly coupled to growth of biomass, and strongly influenced by oxygen consumption.
TL;DR: The data establish regulation of the enzyme formation by enzyme end-product in submerged fermentation and ability of solid state fermentation to minimize it significantly.
Abstract: Alpha-amylase production byBacilluslicheniformis M27 in submerged fermentation was reduced from 480 to 30 units/ml when soluble starch concentration in medium was increased from 0.2 to 1.0%. In contrast, the enzyme production increased by 29 times even with 42 fold increase in the concentration of soluble starch and other starchy substrates in solid state fermentation system. The data establish regulation of the enzyme formation by enzyme end-product in submerged fermentation and ability of solid state fermentation to minimize it significantly. These features were not known earlier.
TL;DR: Competitive lipase-catalysed hydrolyses of triacylglycerols were used for the quantitative determination of the fatty acid profile of several lipases and a complete and reliable activity profile can be obtained in one single experiment.
Abstract: Competitive lipase-catalysed hydrolyses of triacylglycerols were used for the quantitative determination of the fatty acid profile of several lipases. In contrast to previously described methods a complete and reliable activity profile for triacylglycerols containing fatty acid residues with chain lengths from C4 to C18∶1 can be obtained in one single experiment.
TL;DR: An industrial alkaline protease “Alcalase” has been found to be very stable in organic solvents and usable as a catalyst for resolution of N-protected amino acids, in both aqueous solution and organic solvent with high yield and optical purity.
Abstract: An industrial alkaline protease “Alcalase” has been found to be very stable in organic solvents and usable as a catalyst for resolution of N-protected amino acids, in both aqueous solution and organic solvent with high yield and optical purity. Only the L-amino acid ester has been hydrolysed.
TL;DR: The fungus Ceratocystis fimbriata, known to produce among others a banana-like aroma, was optimized to produce characteristic volatile metabolites of this aroma and HPLC was used to separate and quantify some of the metabolites.
Abstract: The fungusCeratocystis fimbriata is known to produce among others a banana-like aroma. With a fractional factorial experimental design a culture medium was optimized to produce characteristic volatile metabolites of this aroma. HPLC was used to separate and quantify some of the metabolites. This showed the influence of the composition of the basal culture medium. It is not yet possible to correlate these results with sensorial evaluation.
TL;DR: In this paper, a new Basidiomycete showed significantly higher degradation rates, 10,000 times for H2S, 40 times for DMS, 15 times for methanethiol (MT) and 4 times for DMDS than any reported previously.
Abstract: A new Basidiomycete showed significantly higher degradation rates, 10,000 times for H2S,40 times for dimethyl sulfide(DMS),15 times for methanethiol(MT) and 4 times for dimethyl disulfide(DMDS) than any reported previously. The optimal pH for degradation activity was around 7. Degradation rate for each gas when mixed gases of H2S,MT and DMS were supplied was almost the same as that for single gas supply. H2S was oxidized to SO4 via SO3 and DMS was stoichiometrically converted to dimethyl sulfoxide(DMSO).