Abstract: It is known that 2,3-butanediol is a potentially valuable chemical feedstock that can be produced from the sugars present in hemicellulose and celluose hydrolysates. Klebsiella oxytoca is able to ferment most pentoses, hexoses, and disaccharides. Butanediol appears to be a primary metabolite, excreted as a product of energy methabolism. The theoretical maximum yield of butanediol from monosaccharides is 0.50 g/g. This article describes the effects of pH, xylose concentration, and the oxygen transfer rate on the bioconversion of D-xylose to 2,3-butanediol. Product inhibition by butanediol is also examined. The most important variable affecting the kinetics of this system appears to be the oxygen transfer rate. A higher oxygen supply favors the formation of cell mass at the expense of butanediol. Decreasing the oxygen supply rate increases the butanediol yield, but decreases the overall conversion rate due to a lower cell concentration.

Abstract: The microbial conversion of organic matter to methane is a process which is becoming increasingly attractive as a method of waste treatment and resource recovery. This article focuses on recent progress made in understanding the microorganisms involved in converting organic matter to methane and the future contributions microbiology will be able to make to improve the process. There are three preliminary points about microbial bioconversion to CH/sub 4/, that the author makes. First, there is generally a greater degree of metabolic specialization in anaerobes than in aerobes. For example, many pure cultures of aerobes can completely mineralize cellulose to CO/sub 2/. However, the conversion of cellulose, or even simpler compounds, to CH/sub 4/ and CO/sub 2/ requires the cooperative interaction of several microbial species. Second, most of the free energy present in the substrate can be found in the methane that is produced. This makes the process attractive, since the methane produced can be burned for energy generation, but it also means that there is less energy available to the organisms involved in breaking down the substrate. The final point is that many of the most important bacteria involved in anaerobic bioconversion are slow-growing, strict anaerobes. These organisms are difficultmore » to culture and isolate, which discouraged many microbiologists from studying them. The recent development of simpler techniques for culturing strict anaerobes has contributed greatly to the recent increase in the isolation rate of new anaerobes.« less

Abstract: Steam-exploded aspenwood chips were acid hydrolysed to their component sugars. Near theoretical solvent yields were achieved in both the acetone-butanol-ethanol (ABE) fermentation and 2,3-butanediol fermentation of these liberated sugars. When Clostridium acetobutylicum was grown on wood hydrolysates, final butanol yields of 9.0 g/L (0.26 g of butanol per g of sugar consumed) were obtained. When Klebsiella pneumoniae was grown on the wood hydrolysates, final butanediol concentrations exceeded 20 g/L, resulting in a bioconversion efficiency approaching 0.5 g of butanediol per g of sugar utilised.

Abstract: The effect of different compounds on the enzymic action of the nitrile-hydratase used for the bioconversion of nitriles was studied. An excess of acrylonitrile as a substrate was shown to inhibit the activity of the enzyme. This inhibition occurred only at relatively high substrate concentrations (0.2 mol/l or more). The nitrile bioconversion products (acrylamide, propionamide) and their structural analogues (acrylic acid, thioacetamide) were shown to inhibit the enzyme competitively. The most important inhibition found was that of cyanide (Ki= 0.004 mol/l), a break down product of some nitriles. By using an acetamidase-negative mutant, amides were shown to inhibit biosynthesis of nitrile-hydratase. An identical result was obtained with thioacetamide, a non-substrate compound for acetamidase. This compound repressed the biosynthesis of nitrile-hydratase by both the wild type and the acetamidase-negative mutant to the same extent.

Abstract: A continuous culture of Zymomonas mobilis produced 60 g/l ethanol over a test period of 39 days. In the presence of oxygen and at ethanol concentrations exceeding 64 g/l, the substrate conversion was incomplete due to growth inhibition. The Zymomonas fermentation was used for ethanol production from an industrial, enzymatically hydrolyzed wheat starch fraction. Continuous cultures converted this substrate with productivities of up to 4.5 g/l.h at ethanol concentrations of 56-60 g/l. The fermentation of glucose derived from wheat starch has been scaled up to 50 cubic m in an industrial plant. Continuous operation has been possible up to 20 days. Disturbances to the process may be mainly due to the presence of lactic acid bacteria in the substrate feed.

Abstract: Ethanol-adaptedCandida utilis efficiently converted ethanol to acetaldehyde, a chemical feedstock of recognized importance. Acetaldehyde which has a low boiling point (21°C) readily evaporates and is easily recovered, thus this bioconversion could provide an energy saving process for efficient recovery of a useful product from low concentrations of ethanol.

Abstract: Streptomyces viridosporus T7A, when used in solid-state fermentation, degrades lignin at high yields to a water-soluble modified polymer, acid precipitable polymeric lignin (APPL) that is useful as an antioxidant, surfactant, and potentially as a component of adhesives and resins. Enhanced strains generated from ultraviolet irradiation mutagenesis and protoplast fusion produced up to 90% more APPL from corn stover lignocellulose than did the wildtype, and they were stable and produced APPL at a faster rate and to a higher final yield than did parental strain T7A. APPLs produced by the wildtype and selected mutants were chemicaly similar polyphenols, but some catabolic enzymes of the genetically manipulated strains were produced in greater amounts.

Abstract: Bioconversion of sterols to 17-ketosteroids by anArthrobacter species occurred in the presence of hydrophobic metal-chelating agents but the production of 17-ketosteroids (17-KS) was seriously limited by the rapis loss of the viability of cells in the presence of these inhibitors. Besides, the conversion was inhibited by 17-KS at concentrations of 500 ppm or more. The 17-KS formed consisted exclusively of l,4-androstadiene-3,17-dione (ADD) and 4-androstene-3, 17-dione (AD) and these were found in the extracellular medium predominantly in bound form or as molecular aggregates which may limit their accumulation. It was concluded that enhanced production of 17-KS could be achieved by protecting the viability of cells and by removing the steroid metabolites from the site of inhibition.

Abstract: This invention provides a semi-continuous fermentation process which is operated in a repeated fed-batch mode to maintain cell bioconversion productivity at a high level without product inhibition of enzymatic activity. The process is illustrated by the bioconversion of toluene or catechol via the ortho pathway to muconic acid which accumulates in the fermentation medium in a quantity up to about 50 grams per liter.

Abstract: TheBrevibacterium sp. R 312 strain possesses a nitrile-hydratase and an amidase, both with a wide substrate spectrum. These two enzymes can be used for the bioconversion of nitriles into the corresponding organic acids: the actions of three types of compounds (nitriles, amides and acids) on the activity of the amidase are reported in the present work.

Abstract: Continuous bioconversion of starch to EtOH by immobilized enzymes and yeasts was studied. Commercial corn starch (10%) was 1st batch-liquefied with bacterial alpha-amylase. In continuous-flow systems, liquefied starch was then converted to glucose with Ca alginate-entrapped fungal glucoamylase, and the resulting glucose was fermented to EtOH by Ca alginate-entrapped active dry yeast. The continuous-flow saccharification-fermentation processes were performed in either 2-stage (sequential) or single-stage (simultaneous) operations. In the single-stage operation, immobilized glucoamylase produced glucose from liquefied starch continuously for 11 days. In the simultaneous saccharification technique using immobilized glucoamylase and yeast mixture in a single-stage column, EtOH production was 69% of theoretical for 5 days. In the 2-stage operation, in which immobilized glucoamylase and yeast were contained in separate columns connected in tandem, EtOH production averaged 97% of theoretical for 5 days. The overall alcoholic production efficiency was significantly greater in the 2-stage system than in the single-stage system.

Abstract: This article shows how glucose and xylose, produced from biomass by hydrolysis with mineral acids, can be fermented to produce a variety of chemical feedstocks including ethanol, organic acids, butanol, and acetone. Agricultural and municipal residues are the most readily available sources of biomass. The bioconversion of biomass involves hydrolysis followed by fermentation. The major components of cellulosic biomass are hemicellulose, cellulose and lignin. Corn stover contains 27% hemicellulose, 43% cellulose, 8% lignin, and 2% ash. Since 60-70% of the biomass is available as carbohydrate, it can be converted into fuels and chemicals by biochemical methods.

Abstract: A combined enzymatic hydrolysis and fermentation (CHF) approach was established for the bioconversion of wood and agricultural residues to butanediol and ethanol. The final butanediol levels obtained from aspenwood xylan or solka floc by the CHF approach were 40-68% greater than the values obtained with the conventional sequential hydrolysis and fermentation approach. The combined cellulose and hemicellulose components of steam-exploded aspenwood and agricultural residues could be directly used by the CHF approach for the production of butanediol and ethanol. The final product yields ranged from 11 to 23 g/100 g original untreated biomass at 34.5-65.4% of the theoretical conversion efficiencies.

Abstract: A combined enzymatic hydrolysis and fermentation (CHF) approach was established for the bioconversion of wood and agricultural residues to butanediol and ethanol. The final butanediol levels obtained from aspenwood xylan or solka floc by the CHF approach were 40-68% greater than the values obtained with the conventional sequential hydrolysis and fermentation approach. The combined cellulose and hemicellulose components of steam-exploded aspenwood and agricultural residues could be directly used by the CHF approach for the production of butanediol and ethanol. The final product yields ranged from 11 to 23 g/100 g original untreated biomass at 34.5-65.4% of the theoretical conversion efficiencies.

Abstract: Process for the bioconversion production of L-ascorbic acid (Vitamin C), and to mocroorganisms (e. g., Candida Norvegensis MF-56, ATCC 20686 and Candida Norvegensis MF-78, ATCC 20732) and bioconversion media which are specifically adapted for such bioconversion.

Abstract: This invention provides hexamethylenediamine muconate salt. This novel salt can be produced by bioconversion of toluene to muconic acid in the presence of hexamethylenediamine. Hydrogenation of this salt provides hexamethylenediamine adipate salt.

Abstract: Although lignocellulose always has been a principal component of man’s food, fuel, and fiber, there has been for the past decade an increased interest in utilization of these materials by new and improved “bioconversion” processes. Since lignocellulose is the most abundant constituent of biomass, attention has been directed to several relatively inexpensive sources, such as agricultural, industrial, and municipal wastes. The biological reactions of the carbon cycle which are responsible for the conversion of lignin and cellulose turn over some 1011 tons/year (1). The variety of microorganisms which mediate the reactions, the extracellular conditions under which the reactions take place, and the products to which lignocellulose is converted are of scientific interest as well as being potentially valuable for technological applications. Studies of these processes range from determination of precise chemical mechanisms to analysis of microbial associations responsible for the multiplicity of reactions needed to convert the heterogeneous lignocellulose to metabolic intermediates and end products.

Abstract: This support is of the type comprising at least one cloth sheet, woven or nonwoven, made from a rotproof material According to the invention, each one 12 is provided, on at least of its faces, with a plurality of pompoms 17 evenly distributed on its surface, made from a plurality of threads joined to each other Application to the production of digesters for methane bioconversion

Abstract: L-malic acid is produced in a concentration of 170 to 400 g per liter and high yield by biotechnical conversion of fumaric acid neutralized with ammonium hydroxide in nutrient-free solution or suspension. Pure L-malic acid can be obtained economically therefrom with high efficiency in a quality suitable for food and pharmaceutical use. The fermentation can be carried out in simple vessels under non-sterile conditions. The conversion rate of the fumarate and the attainable concentration of L-malate are promoted by the ammonium ions.

Abstract: The bioconversion of 9,10-dihydroanthracene to anthraquinone as the major product has been performed by a mixed bacterial population.

Abstract: This invention provides a process for the bioconversion of a non-growth aromatic feed to an accumulated quantity of a 2-hydroxymuconic semialdehyde intermediate, which subsequently is converted by chemical means to picolinic acid and pyridine products.

Abstract: Laboratory results are presented of the bioconversion of cellulose from cocoa pod husks, utilizing cellulase from three mutants of Trichoderma reesei. Total reducing sugars in filtered hydrolysates were estimated by the dinitrosalicylic acid method. The sugars present were identified by paper chromatography as glucose and xylose.

Abstract: 1. A process for producing the pure L-isomer of malic acid from neutralized fumaric acid under bioconversion conditions by free movable microorganisms in an aqueous solution of fumarate characterized in that said microorganisms are fungi, that the initial concentration of fumarate is 11 to 15 % by weight and that the concentration of L-malic acid at the time of harvesting is 100 to 170 g per liter of fermentation broth.