Showing papers in "Biotechnology Letters in 1982"
TL;DR: The yeast, Pachysolen tannophilus, can utilize the pentose D-xylose with accumulation of significant quantities of ethanol with the help of NADPH-linked D-Xylose reductase and NAD-dependent D- xylitol dehydrogenase.
Abstract: The yeast, Pachysolen tannophilus, can utilize the pentose D-xylose with accumulation of significant quantities of ethanol. Cell extracts of the organism contain NADPH-linked D-xylose reductase (aldose reductase EC 1.1.1.21) and NAD-dependent D-xylitol dehydrogenase (D-xylulose reductase EC 1.1.1.9). D-Xylose was required for induction of both the D-xylitol dehydrogenase and the D-xylose reductase. Neither enzyme was found in glucose grown cell-free extracts.
103 citations
TL;DR: Lactic acid was produced by viable Lactobacillus delbreuckii NRRL-B445 in a hollow fiber fermenter and the observed cell yields were appreciably lower than batch cell yields.
Abstract: Lactic acid was produced by viable Lactobacillus delbreuckii NRRL-B445 in a hollow fiber fermenter. Final cell densities in the fluid surrounding the fibers in the fermenter were apparently as high as 480 gms DW/L, and volumetric productivities reached 100 gms/L-hr lactic acid. The observed cell yields were appreciably lower than batch cell yields.
98 citations
TL;DR: It is concluded that enzyme denaturation is unlikely to play a direct part in ethanol tolerance, but inhibition by ethanol may be responsible for slowing some of the glycolytic reactions.
Abstract: An investigation of the effects of ethanol on both the stabilities and activities of glycolytic enzymes of yeast and Zymomonas mobilis is presented. It is concluded that enzyme denaturation is unlikely to play a direct part in ethanol tolerance, but inhibition by ethanol may be responsible for slowing some of the glycolytic reactions.
88 citations
TL;DR: Data of other workers has been found to fit the model and the inhibitory effect of ethanol on the yeast Saccharomyces cerevisiae ATCC 4126 has been studied in continuous culture under conditions where high concentrations of ethanol were produced by the yeast itself.
Abstract: The inhibitory effect of ethanol on the yeast Saccharomyces cerevisiae ATCC 4126 has been studied in continuous culture under conditions where high concentrations of ethanol were produced by the yeast itself. The fermentations were carried out using a glucose, salts medium at glucose concentrations of 20, 100 and 200 gl-1. The growth function
$$\mu = \hat \mu \cdot \frac{{C_s }}{{K_s + C_s }} \cdot \frac{{K_p }}{{K_p + Y_{ps} /\left( {C_{sf} - C_s } \right)}}$$
was found to describe the observed data with
$$\hat \mu = 1,64h^{ - 1} ,K_s = 3,3g\ell ^{ - 1} $$
$$K_p = 5,2g\ell ^{ - 1} $$
and
$$Y_{ps} = 0,43$$
as the values of the kinetic parameters. Data of other workers has also been found to fit the model.
83 citations
TL;DR: In this paper, mixed culture filtrates of T. reesei and A. wentii were used to obtain fermentable sugars, which were then treated to remove undesired impurities to produce butanol to the extent of 16 g/l.
Abstract: Agricultural residues such as bagasse and rice straw have been hydrolyzed by mixed culture filtrates of T. reesei and A. wentii to obtain fermentable sugars. After the hydrolyzate had been treated to remove undesired impurities, Cl. saccharoper butylacetonicum was used to produce butanol to the extent of 16 g/l.
80 citations
TL;DR: In this article, living Lactobacillus delbrueckii cells were entrapped in calcium alginate gel beads and employed both in recycle batch and continuous column reactors to produce l-lactic acid from glucose.
Abstract: Living Lactobacillus delbrueckii cells were entrapped in calcium alginate gel beads and employed both in recycle batch and continuous column reactors to produce l-lactic acid from glucose. The substrate contained l% (w/v) yeast extract as nutrient and 4.8% (w/v) solid calcium carbonate as buffer. The maxiumum lactic acid yield obtained was 97%, of which more than 90% was l-lactic acid. The biocatalyst activity half-life in continuous operation was about 100 d, and only about 10% of the activity was lost during intermittent storage of the bioreactor at +7°C for about 5 months.
80 citations
TL;DR: Clostridium acetobutylicum was grown in continuous culture under ammonium limitation and a decrease of the pH to values between 5.2 and 4.3 resulted in a shift of the fermentation towards acetone-butanol formation.
Abstract: Clostridium acetobutylicum was grown in continuous culture under ammonium limitation (15.15 mM NH4+). At a pH of 6.0 and at various dilution rates only acetate, butyrate and ethanol were formed as non-gaseous products. A decrease of the pH to values between 5.2 and 4.3 resulted in a shift of the fermentation towards acetone-butanol formation.
62 citations
TL;DR: In this article, conditions for pretreating aspen wood chips were optimized so that highest amounts of undegraded hemicellulose could be obtained after washing the steam exploded chips.
Abstract: Previously steam explosion had been used to enhance the enzymatic hydrolysis of lignocellulosic substrates to glucose. The conditions for pretreating aspen wood chips were optimized so that highest amounts of undegraded hemicellulose could be obtained after washing the steam exploded chips. The hemicellulose rich water soluble fractions showing highest pentosan yields were then acid hydrolysed to their composite sugars. Approximately 65–75% of the total reducing sugars detected in the wood hydrolysates were in the form of monosaccharides with D-xylose being the major component. Klebsiella pneumoniae was grown in media containing these wood hydrolysates as the substrate and 2,3-butanediol yields of 0.4–0.5 g per g of monosaccharide utilised were obtained.
62 citations
TL;DR: Silicalite, a zeolite analogue, has been used to adsorb n-butanol from fermentation liquors as mentioned in this paper, providing a possible alternative to distillation for product recovery, and may alleviate the problem of product inhibition during fermentation.
Abstract: Silicalite, a zeolite analogue, has been used to adsorb n-butanol from fermentation liquors. 85 mg butanol/g silicalite can be adsorped. This provides a possible alternative to distillation for product recovery, and may alleviate the problem of product inhibition during fermentation.
61 citations
TL;DR: Phenylalanine synthesis from glucose and ammonia was studied using a hyperproducing mutant of Escherichia coli to study kinetic parameters and results were similar to batch culture values.
Abstract: Phenylalanine synthesis from glucose and ammonia was studied using a hyperproducing mutant of Escherichia coli. Kinetic parameters (typical values : 8.7 g phenylalanine/l, yield on glucose 0.19 g/g, productivity 0.44 g/l/h) were similar to batch culture values.
60 citations
TL;DR: In a continuous flow fluidized bed reactor sustained photosynthesis, N2-fixation, and ammonia production have been achieved over a 130 hour period, the longest tested.
Abstract: Whole filaments of the N2-fixing cyanobacterium Anabaena ATCC 27893 have been immobilized by entrapment in calcium alginate gel beads. In a continuous flow fluidized bed reactor sustained photosynthesis, N2-fixation, and ammonia production have been achieved over a 130 hour period, the longest tested.
TL;DR: Both free and immobilized cells of the algae Chlorella vulgaris and Anacystis nidulans contain aminoacid oxidase (AAO) activity which is increased by illumination with red light, which results in increased production of keto acid.
Abstract: Both free and immobilized cells of the algae Chlorella vulgaris and Anacystis nidulans contain aminoacid oxidase (AAO) activity which is increased by illumination with red light. Both immobilized species are photosynthetically active. By co-immobilizing Chlorella with bacterial cells (Providencia sp. PCM 1298) containing high AAO activity an increased production of keto acid (up to tenfold) is observed due to improved oxygen supply.
TL;DR: Maltose transport in S. cerevisiae was inhibited by ethanol and other alkanols in a non-competitive way, indicating that inhibition is due to an alteration of the lipid environment of the maltose transport system in the plasma membrane.
Abstract: Maltose transport in S. cerevisiae was inhibited by ethanol and other alkanols in a non-competitive way. The Michaelis constant, Km, for the sugar, with or without alkanols was 5.9 mM, whereas the maximum trans port capacity, Vmax, decreased exponentially with alkanols concentration. The inhibitory capacity was positively correlated with the lipid solubility of the alkanols, indicating that inhibition is due to an alteration of the lipid environment of the maltose transport system in the plasma membrane.
TL;DR: Application of Schwanniomyces yeasts to single cell protein or alcohol production is feasible based on cell yields of 60% aerobically, and ethanol yields of 86% of theoretical in associative fermentation.
Abstract: Application of Schwanniomyces yeasts to single cell protein or alcohol production is feasible based on cell yields of 60% aerobically, and ethanol yields of 86% of theoretical in associative fermentation.
TL;DR: The utilization of sugars present in wood hemicellulose by Klebsiella pneumoniae was investigated and production of 2, 3-butanediol was optimal under anaerobic conditions with all sugars tested, with the exception of D-xylose which appeared to require a finite air supply for maximal diol yield.
Abstract: The utilization of sugars present in wood hemicellulose byKlebsiella pneumoniae was investigated. Production of 2, 3-butanediol was optimal under anaerobic conditions with all sugars tested, with the exception of D-xylose which appeared to require a finite air supply for maximal diol yield. Anaerobic growth and solvent production of the organism on individual sugars revealed a similar pattern: diol production occurred generally at late exponential phase, concomitant with a culture off drop, and continued into stationary phase of growth. Solvent yields of 0.69 moles of 2, 3-butanediol and 0.69 moles of ethanol could be obtained per mole of D-glucose fermented anaerobically, while 0.45 moles of diol and 0.34 moles of ethanol were obtained per mole of xylose fermented under conditions of finite air supply.
TL;DR: The addition of calcium carbonate to the media to enhance xylose utilized was beneficial although lower butanol values were obtained.
Abstract: Clostridium acetobutylicum was grown on a variety of different media and assayed for enhanced butanol production. Butanol values of about 90% of theoretical were obtained when glucose was used as the substrate. Five other sugars were assayed and the order of butanol production using these substrates was cellobiose>mannose>arabinose>xylose >galactose. The addition of calcium carbonate to the media to enhance xylose utilized was beneficial although lower butanol values were obtained.
TL;DR: The ammonia ion selective electrode method was the most practical and the most convenient one for measuring the ammonia nitrogen in methanogenic sludge because of its simplicity, rapidity, high precision and accuracy, freedom from interference, small sample size, and possibility for continuous monitoring.
Abstract: The ammonia ion selective electrode method was the most practical and the most convenient one for measuring the ammonia nitrogen in methanogenic sludge. This is because of its simplicity, rapidity, high precision and accuracy, freedom from interference, small sample size, and possibility for continuous monitoring.
TL;DR: In this paper, the optimum temperature for fermentation by Saccharomyces uvarum was found to be higher than that for its growth, and fermentation continued at temperatures above the growth maximum (40°C).
Abstract: The optimum temperature for fermentation by Saccharomyces uvarum was found to be higher than that for its growth. Fermentation continued at temperatures above the growth maximum (40°C). S.uvarum was most resistant to growth inhibition by ethanol at temperatures 5°C and 10°C below its growth optimum (35°C). Fermentation became more resistant to ethanol inhibition with increasing temperature.
TL;DR: Batch and fed-batch operation over a range of substrate concentrations are compared, which provides a means of avoiding the agitation and aeration difficulties, as well as repression effects encountered with high substrate concentration batch fermentation.
Abstract: Use of a fed-batch mode of cultivation of T. reesei has permitted high concentrations of substrate to be consumed. This has resulted in the production of high titre cellulase preparations around 30 FPU/ml at high volumetric productivities (177 IU/L.hr). Perhaps the most obvious area for major improvement in the process of cellulose utilization is the production of cellulase enzyme for hydrolysis of wood and agricultural residues. It has been estimated that some 50% of the cost of producing glucose from cellulosic material is attributable to enzyme production alone (Perez, et al., 1980). Improvements in the area would therefore have a dramatic impact, and are of paramount importance if economical hydrolysis processes are to be realized. The first major thrust in the area has been the development of improved mutant strains of T. reesei, free from catabolite repression and capable of constitutive cellulase production (Montenecourt and Eveleigh, 1977; Gallo, 1982). While this effort continues to develop further high yielding mutants, improvement must also come from developments in fermentation techniques. A major advance is the use of fed-batch cultivation, which provides a means of avoiding the agitation and aeration difficulties, as well as repression effects encountered with high substrate concentration batch fermentation. This report briefly compares batch and fed-batch operation over a range of substrate concentrations.
TL;DR: The possible role of sophorolipids from Torulopsis bombicola was investigated in alkane fermentation and it was found that they may act as a specific growth factor for Yeasts on insoluble alkanes.
Abstract: The possible role of sophorolipids from Torulopsis bombicola was investigated in alkane fermentation. Sophorolipids and related model compounds specifically stimulated the growth of strains of Torulopsis yeasts on insoluble alkanes and may act as a specific growth factor. There may be more than one way for a yeast to be stimulated to incorporate alkanes for growth.
TL;DR: In this article, experiments were conducted with Zymomonas mobilis in an attached film expanded bed (AFEB) fermentor at different dilution rates, using a feed glucose concentration of 100 gm/l.
Abstract: Experiments were conducted with Zymomonas mobilis in an attached film expanded bed (AFEB) fermentor at different dilution rates, using a feed glucose concentration of 100 gm/l. Vermiculite was used as the bed material for attachment of the bacterial film. Ethanol volumetric productivities were maximum at a dilution rate of 3.6hr-1. The productivities were 105 gm/l-hr and 210 gm/l-hr based on total fermentor volume and bed volume, respectively.
TL;DR: It was found that at low densities the fermentation of glucose was essentially acidogenic in nature, whereas acetone and butanol were the major end-products when the cultures were maintained at a high cell density.
Abstract: Turbidostat cultures of Clostridium acetobutylicum were analysed with respect to their fermentation products after steady states were obtained at various cell densities. It was found that at low densities the fermentation of glucose was essentially acidogenic in nature, whereas acetone and butanol were the major end-products when the cultures were maintained at a high cell density.
TL;DR: In this article, a gas meter based on the total counts of impulsions corresponding to the successive filling and emptying operations of a calibrated flask is described. And an example of application to the methane fermentation is reported.
Abstract: A device for measuring low rates of gas flow is described and an example of application to the methane fermentation is reported. Its principle is based on the total counts of impulsions corresponding to the successive filling and emptying operations of a calibrated flask. This gas meter can be used for flow rates ranging from milliliters- to liters per day.
TL;DR: In this paper, the effects of pH (5.0 to 8.0), temperature (30°C to 40°C), and initial glucose concentration (75 g/l to 150g/l) on the kinetics of ethanol production from glucose using batch fermentation were evaluated.
Abstract: Zymomonas mobilis, strain ATCC 10988, was used to evaluate the effects of pH (5.0 to 8.0), temperature (30°C to 40°C), and initial glucose concentration (75 g/l to 150 g/l) on the kinetics of ethanol production from glucose using batch fermentation. Specific ethanol production rate was maximum and nearly constant over a pH range of 6.0 to 7.5. End-of-batch ethanol yield and specific growth rate were insensitive to pH in the range of 5.0 to 7.5. End-of-batch ethanol yield was maximum and nearly constant between 30°C and 37°C but decreased by 24% between 37°C and 40°C. All other kinetic parameters are greatest at 34°C. End-of-batch ethanol yield is maximum at an initial glucose concentration of 100 g/l. Specific growth rate reaches a maximum at 75 g/l, but specific ethanol production rate decreases throughout the range. The optimum initial glucose concentration of 100 g/l gives the highest ethanol yield at a specific ethanol production rate less than 10% below the maximum observed.
TL;DR: Cellulase production by Trichoderma reesei mutant RUT-C30, immobilized on 4% κ-carrageenan beads, was monitored in continuous culture for 13 days and carbon and nitrogen requirements were reduced to 1/4-1/2 those of conventional continuous culture.
Abstract: Cellulase production by Trichoderma reesei mutant RUT-C30, immobilized on 4% κ-carrageenan beads, was monitored in continuous culture for 13 days. Cellulase production averaged 26.0 Filter Paper Units (FPU)/l/hr; carbon and nitrogen requirements per FPU produced were reduced to 1/4-1/2 those of conventional continuous culture.
TL;DR: Production of ethanol from cellodextrins, as large as cellohexose, byCandida lusitaniae and C. wickerhamii was studied and it was found that the former fermented only glucose and cellobiose, whereas the latter efficiently fermented cellodeXTrins.
Abstract: Production of ethanol from cellodextrins, as large as cellohexose, byCandida lusitaniae andC. wickerhamii was studied.C. lusitaniae fermented only glucose and cellobiose, whereasC. wickerhamii efficiently fermented cellodextrins. Maximum ethanol yields of 29.2 g/liter from 54 g/liter cellodextrins were achieved byC. wickerhamii in 3–4 days.
TL;DR: The yeast Schwanniomyces alluvius ferments soluble starch to ethanol at a conversion efficiency of greater than 95% with only trace amounts of side products are detectable as discussed by the authors.
Abstract: The yeast Schwanniomyces alluvius ferments soluble starch to ethanol at a conversion efficiency of greater than 95%. Only trace amounts of side products are detectable.
TL;DR: A flocculent mutant of Zymomonas mobilis has been isolated and kinetic studies carried out in batch and continuous culture, and the specific rates of glucose uptake and ethanol production were decreased by 20%.
Abstract: A flocculent mutant of Zymomonas mobilis has been isolated and kinetic studies carried out in batch and continuous culture. By comparison with the parent strain the specific rates of glucose uptake and ethanol production were decreased by 20%. Cell recycle and semibatch cultures with the flocculent strain resulted in relatively high productivities (viz. 50 g/l/h). However semibatch culture had the additional advantages of an increased ethanol concentration (viz. 82 g/l) and a more stable and controlled environment for cell separation.
TL;DR: Saccharomyces uvarum cells immobilized in the porous carrier showed high ethanol productivities with a maximum value of 25 g/l when monitored in packed bed reactors at 35°C with continuous cane molasses feedstock containing 10% fermentable sugars.
Abstract: Open pore gelatin pellets with entrapped yeast cells were obtained by selective leaching out of Ca alginate from the composite matrix followed by crosslinking with glutaraldehyde. Saccharomyces uvarum cells immobilized in the porous carrier showed high ethanol productivities with a maximum value of 25 g/l.h when monitored in packed bed reactors at 35°C with continuous cane molasses feedstock containing 10% fermentable sugars.
TL;DR: In this paper, a strain of Pachysolen tannophilus was used to ferment D-Xylose to ethanol, and the yeast would not grow at this pH when the initial pH of the medium was less than 3.0.
Abstract: D-Xylose was fermented to ethanol by a strain ofPachysolen tannophilus in yields greater than 0.3g ethanol per g xylose consumed. Ethanol production was influenced by xylose concentration and was at a maximum at 10%, w/v. Ethanol formation occurred at pH 2.75-2.50 but the yeast would not grow at this pH when the initial pH of the medium was less than 3.0. Ethanol was consumed by the yeast when the xylose concentration became limiting. L-Arabinose, D-glucose, D-fructose, cellobiose, D-glucuronic acid, but not sucrose,were also fermented to ethanol byPachysolen tannophilus. Kinetic studies on xylose fermentation established various parameters involved in growth, substrate utilization and ethanol formation when the yeast was fermenter grown.