Showing papers on "Fermentation published in 1983"
TL;DR: An overview of the following topics is given: main pathways of homo- and heterofermentation of hexoses, i.e. glycolysis, bifidus pathway, 6-phosphogluconate pathway; uptake and dissimilation of lactose (tagatose pathway); fermentation of pentoses and pentitols; alternative fates of pyruvate.
Abstract: The term “lactic acid bacteria” is discussed. An overview of the following topics is given: main pathways of homo- and heterofermentation of hexoses, i.e. glycolysis, bifidus pathway, 6-phosphogluconate pathway; uptake and dissimilation of lactose (tagatose pathway); fermentation of pentoses and pentitols; alternative fates of pyruvate, i.e. splitting to formate and acetate, CO2 and acetate or formation of acetoin and diacetyl; lactate oxidation; biochemical basis for the formation of different stereoisomers of lactate.
800 citations
TL;DR: During oxygen limitation in animals, glucose can be fermented via several metabolic pathways varying in energetic efficiency and leading to various end products (such as lactate, alanopine, octopine), succinate, or propionate.
Abstract: During oxygen limitation in animals, glucose can be fermented via several metabolic pathways varying in energetic efficiency and leading to various end products (such as lactate, alanopine, octopine, succinate, or propionate). Because of opposite pH dependencies of proton production by fermentation and by hydrolysis of adenosine triphosphate formed in the fermentation, the total number of moles of protons generated is always two per mole of the fermentable substrate. However, two and three times more adenosine triphosphate can be turned over per mole of protons produced in succinate and propionate fermentations, respectively, than in lactate fermentation.
562 citations
TL;DR: In this paper, byproduct production rates and inhibition levels in continuous fermentation with Saccharomyces cerevisiae have been determined for acetaldehyde, glycerol, formic, lactic, and acetic acids, 1-propanol, 2-methyl-1-butanol, and 2,3-butanediol.
Abstract: Inhibition by secondary fermentation products may limit the ultimate productivity of new glucose to ethanol fermentation processes. New processes are under development whereby ethanol is selectively removed from the fermenting broth to eliminate ethanol inhibition effects. These processes can concentrate minor secondary products to the point where they become toxic to the yeast. Vacuum fermentation selectively concentrates nonvolatile products in the fermentation broth. Membrane fermentation systems may concentrate large molecules which are sterically blocked from membrane transport. Extractive fermentation systems, employing nonpolar solvents, may concentrate small organic acids. By-product production rates and inhibition levels in continuous fermentation with Saccharomyces cerevisiae have been determined for acetaldehyde, glycerol, formic, lactic, and acetic acids, 1-propanol, 2-methyl-1-butanol, and 2,3-butanediol to assess the potential effects of these by-products on new fermentation processes. Mechanisms are proposed for the various inhibition effects observed.
380 citations
TL;DR: The main carbohydrate passing from the ileum to the cecum is polysaccharide from plant cell walls (dietary fiber) and residual starch that has escaped digestion.
309 citations
01 Sep 1983
TL;DR: A hypothesis is put forward which explains that ethanol production from xylose by yeast under anaerobic conditions is negligible, and it is suggested that the failure to fermentxylose anaerobically is due to a discrepancy between production and consumption of NADH in the overall conversion of xylOSE to ethanol.
Abstract: The kinetics of glucose and xylose utilization by batch cultures of Candida utilis were studied under aerobic and anaerobic conditions during growth in complex media. Rapid ethanol formation occurred during growth on glucose when aerobic cultures were shifted to anaerobic conditions. However, with xylose as a substrate, transfer to anaerobiosis resulted in an immediate cessation of metabolic activity, as evidenced by the absence of both ethanol formation and xylose utilization. The inability of the yeast to ferment xylose anaerobically was not due to the absence of key enzymes of the fermentation pathway, since the addition of glucose to such cultures resulted in the immediate conversion of glucose to ethanol. Furthermore, when the enzyme xylose isomerase was added to an anaerobic xylose culture, immediate conversion of xylose to ethanol was observed. This indicates that the inability of the yeast to form ethanol from xylose under anaerobic conditions is caused by metabolic events associated with the conversion of xylose to xylulose. A hypothesis is put forward which explains that ethanol production from xylose by yeast under anaerobic conditions is negligible. It is suggested that the failure to ferment xylose anaerobically is due to a discrepancy between production and consumption of NADH in the overall conversion of xylose to ethanol. When a hydrogen acceptor (i.e. acetoin) was added to anaerobic cultures of C. utilis, xylose utilization resumed, and ethanol and acetate were produced with the concomitant stoicheiometric reduction of acetoin to 2,3-butanediol.
270 citations
01 Nov 1983
TL;DR: It was demonstrated that the formation of acetone was initiated by the action of a coen enzyme A-transferase which transferred coenzyme A from acetoacetyl-CoA to either acetate or butyrate.
Abstract: Clostridium acetobutylicum cells were collected from chemostats which were run at pH 4.3 or 6.0 and which produced either acetone-butanol or acetate-butyrate; they were used to determine the level of enzymes involved either in solvent or in acid formation. The highest activity of phosphotransacetylase, phosphotransbutyrylase, acetate kinase, and butyrate kinase was found in cells which carried out an acetate-butyrate fermentation; these enzymes were present in solvent-producing cells at a level of about 10–50% as compared to acid-producing cells. Hydrogenase activity was detectable in approximately the same amounts in both cell types; however, in solvent-producing cells it was only measurable following a lag-period. Butyraldehyde and butanol dehydrogenases were found in small amounts exclusively in solvent-producing cells. It was demonstrated that the formation of acetone was initiated by the action of a coenzyme A-transferase which transferred coenzyme A from acetoacetyl-CoA to either acetate or butyrate. This coenzyme A-transferase as well as acetoacetate decarboxylase were hardly detectable in acid-producing cells, but reached high levels in solvent producing cells. Similar changes of the activity of the enzymes mentioned were observed when a batch culture was shifted from acid to solvent formation.
244 citations
TL;DR: A strain ofCandida shehatae fermented 9% D-xylose directly to ethanol within 40 hours with a yield coefficient of 0.29, which compared favourably with the published data for other xylose-fermenting microorganisms.
Abstract: A strain ofCandida shehatae fermented 9% D-xylose directly to ethanol within 40 hours with a yield coefficient of 0.29. The specific rate of ethanol production attained a maximum value of 0.28 g ethanol (g cells h)−1. The aeration rate greatly influenced the fermentation parameters. The performance of this yeast compared favourably with the published data for other xylose-fermenting microorganisms.
199 citations
TL;DR: An HPLC technique is described for the analysis of organic acids in lactic acid fermented vegetables and separation data are presented for oxalic, citric, tartaric, malic, succinic, lactic, formic, acetic, propionic, and butyric acids.
Abstract: An HPLC technique is described for the analysis of organic acids in lactic acid fermented vegetables. An Aminex HPX-87 column with 0.013 M-H2SO4 as mobile phase was used. Separation data are presented for oxalic, citric, tartaric, malic, succinic, lactic, formic, acetic, propionic, and butyric acids. Interference problems from sugars are also reported.
178 citations
TL;DR: A strain of Streptomyces was found to produce new antifungal antibiotics and leptomycins A and B exhibit strong inhibitory activity against Schizosaccharomyces and Mucor.
Abstract: A strain of Streptomyces was found to produce new antifungal antibiotics. The active compounds were purified and separated into two substances named leptomycin A and B by high performance liquid chromatography. The molecular formulae of leptomycins A and B are C32H46O6 and C33H48O6 respectively, and physicochemical and biological properties of them are very similar to each other. Leptomycins A and B exhibit strong inhibitory activity against Schizosaccharomyces and Mucor.
166 citations
TL;DR: The synthetic polyether polyethylene glycol (PEG) with a molecular weight of 20,000 was anaerobically degraded in enrichment cultures inoculated with mud of limnic and marine origins and described as the type strain of a new species, Pelobacter venetianus sp.
Abstract: The synthetic polyether polyethylene glycol (PEG) with a molecular weight of 20,000 was anaerobically degraded in enrichment cultures inoculated with mud of limnic and marine origins. Three strains (Gra PEG 1, Gra PEG 2, and Ko PEG 2) of rod-shaped, gram-negative, nonsporeforming, strictly anaerobic bacteria were isolated in mineral medium with PEG as the sole source of carbon and energy. All strains degraded dimers, oligomers, and polymers of PEG up to a molecular weight of 20,000 completely by fermentation to nearly equal amounts of acetate and ethanol. The monomer ethylene glycol was not degraded. An ethylene glycol-fermenting anaerobe (strain Gra EG 12) isolated from the same enrichments was identified as Acetobacterium woodii. The PEG-fermenting strains did not excrete extracellular depolymerizing enzymes and were inhibited by ethylene glycol, probably owing to a blocking of the cellular uptake system. PEG, some PEG-containing nonionic detergents, 1,2-propanediol, 1,2-butanediol, glycerol, and acetoin were the only growth substrates utilized of a broad variety of sugars, organic acids, and alcohols. The isolates did not reduce sulfate, sulfur, thiosulfate, or nitrate and were independent of growth factors. In coculture with A. woodii or Methanospirillum hungatei, PEGs and ethanol were completely fermented to acetate (and methane). A marine isolate is described as the type strain of a new species, Pelobacter venetianus sp. nov. Its physiology and ecological significance, as well as the importance and possible mechanism of anaerobic polyether degradation, are discussed.
154 citations
TL;DR: When the growth of aerobic spoilage bacteria is inhibited, lactic acid bacteria may become the dominant component of the microbial flora of meats and this occurs with cured meats and with meats packaged in films of low gas permeability.
Abstract: When the growth of aerobic spoilage bacteria is inhibited, lactic acid bacteria may become the dominant component of the microbial flora of meats. This occurs with cured meats and with meats packaged in films of low gas permeability. The presence of a flora of psychrotrophic lactic acid bacteria on vacuum-packaged fresh chilled meats usually ensures that shelf-life is maximal. When these organisms spoil meats it is generally by causing souring, however other specific types of spoilage do occur. Some strains cause slime formation and greening of cured meats, and others may produce hydrogen sulphide during growth on vacuum-packaged beef. The safety and stability of fermented sausages depends upon fermentation caused by lactic acid bacteria. Overall the presence on meats of lactic acid bacteria is more desirable than that of the types of bacteria they have replaced.
TL;DR: Strain YSRA-1 is described as the type strain of the new genus and species Thermodesulfobacterium commune, a new species of thermophile associated with volcanic activity in Yellowstone National Park which proliferated at temperatures above 45 °C but below 85 °C, and had an optimum growth temperature of 70 °C.
Abstract: SUMMARY: Microbial sulphate reduction was examined in thermal waters, sediments and decomposing algal-bacterial mats associated with volcanic activity in Yellowstone National Park. In vivo radioactive tracer studies which demonstrated biological [35S]sulphkie production from [35S]sulphate at temperatures higher than 50 °C but less than 85 °C, correlated with the presence of a unique sulphate-reducing bacterium. This new species proliferated at temperatures above 45 °C but below 85 °C, and had an optimum growth temperature of 70 °C. The organism was a small Gram-negative, straight rod which displayed an outer-wall membranous layer in thin sections. This obligate anaerobe utilized pyruvate, lactate or H2 as electron donors and sulphate or thiosulphate as electron acceptors for growth and sulphide formation. Pyruvate alone was fermented during growth to hydrogen, acetic acid and CO2. Cell extracts contained cytochrome c
3 but lacked a desulphoviridin-type bisulphite reductase. The DNA guanosine plus cytosine content was 34.4 ±1.0 mol%. Other unusual biochemical features of this extreme thermophile are discussed. Strain YSRA-1 is described as the type strain of the new genus and species Thermodesulfobacterium commune.
TL;DR: Mutant yeast strains that exhibit different metabolic product patterns can be induced and isolated from Candida sp.
Abstract: The utilization and conversion of D-xylose, D-xylulose, L-arabinose, and xylitol by yeast strains have been investigated with the following results: (1) The majority of yeasts tested utilize D-xylose and produce polyols, ethanol, and organic acids. The type and amount of products formed varies with the yeast strains used. The most commonly detected product is xylitol. (2)The majority of yeasts tested utilize D-xylulose aerobically and fermentatively to produce ethanol, xylitol, D-arabitol, and organic acids. The type and amount of products varies depending upon the yeast strains used. (3) Xylitol is a poor carbon and energy source for most yeasts tested. Some yeast strains produce small amounts of ethanol from xylitol. (4) Most yeast strains utilize L-arabinose, and L-arabitol is the common product. Small amounts of ethanol are also produced by some yeast strains. (5) Of the four substrates examined, D-xylulose was the perferred substrate, followed by D-xylose, L-arabinose, and xylitol. (6) Mutant yeast strains that exhibit different metabolic product patterns can be induced and isolated from Candida sp. Saccharomyces cerevisiae, and other yeasts. These mutant strains can be used for ethanol production from D-xylose as well as for the study of metabolic regulation of pentose utilization in yeasts.
TL;DR: It was shown that the growth of lactic acid bacteria during alcoholic fermentation depends on the composition of the must, and the survival of Leuconostoc oenos in wines after malolactic fermentation depended on wine pH, alcohol concentration, SO(2) concentration, and temperature of storage.
Abstract: We showed that the growth of lactic acid bacteria during alcoholic fermentation depends on the composition of the must. We illustrated how the addition of sulfur dioxide to the must before fermentation and the temperature of storage both affect the growth of these bacteria in the wine. Whereas species of Lactobacillus and Leuconostoc mesenteroides were isolated from grapes and must, Leuconostoc oenos was the only species isolated after alcoholic fermentation. This organism was responsible for the malolactic fermentation. Isolates of this species varied in their ability to ferment pentoses and hexoses. The survival of Leuconostoc oenos in wines after malolactic fermentation depended on wine pH, alcohol concentration, SO2 concentration, and temperature of storage.
TL;DR: In this paper, a natural lactic acid fermentation of corn significantly reduced phytate levels and thus increased the amount of Fiske-Subbarow positive phosphorus (free).
Abstract: Natural lactic acid fermentation of corn significantly reduced phytate levels and thus increased the amount of Fiske-Subbarow positive phosphorus (free). Sixteen bacterial strains isolated from a natural lactic fermentation of corn meal had active phytases.
TL;DR: Various forms of liquid‐liquid extraction systems are being developed to separate products, such as ethanol and volatile fatty acids (VFA), from fermentation liquids, since distillation is energetically expensive.
Abstract: Various forms of liquid-liquid extraction systems are being developed to separate products, such as ethanol and volatile fatty acids (VFA), from fermentation liquids, since distillation is energetically expensive. Continuous extraction is advantageous, as product inhibition of the fermentation is minimized. However, some extraction solvents may be toxic or inhibitory to microorganisms.Thirty organic chemicals were examined by means of a small scale (60 mL) batch fermentation bioassay procedure for their toxicity to a commercial inoculum (Methanobac, W.B.E. Ltd.), which was a mixed culture of facultatively anaerobic, acid-producing bacteria. Gas production, pH change of medium, and the concentrations of ethanol, VFA, and lactic acid were measured after 75 h growth. The optimum experimental conditions for toxicity testing were alfalfa as substrate (2 g), a buffered nutrient medium (pH 6.8), "Methanobac" inoculum (10 mL), and test chemicals at levels between 10 and 100 microL/mL.Thirteen chemicals were nontoxic, and included the paraffins (C(6)-C(12)), phthalates, organophosphorus compounds, Freon 113 (1,1,2-trichloro-1,2,2-trifluoro ethane), Aliquat 336 (tricaprylylmethyl ammonium chloride), di-isoamyl ether, and trioctylamine. Other amine extractants were partially toxic. Alcohols (C(5)-C(12)), ketones (C(5)-C(8)), benzene derivatives, isoamyl acetate, and di-isopropyl ether were toxic. Generally, the chemicals were not toxic unless present at levels in excess of that expected to be required to saturate the aqueous phase.Total gas production was a good indicator of toxicity even within 24 h, but the presence of homofermentative (nongas producing) lactic acid bacteria complicated interpretation."Methanobac" inoculum was compared with an inoculum derived from a rumen culture for four test chemicals. The results were essentially the same. However, the toxicity of a chemical to bacteria is likely to vary considerably between bacterial species.
Patent•
16 Sep 1983
TL;DR: Hyaluronic acid, a polysaccharide, is prepared in high yield from streptococcus bacteria by fermenting the bacteria under anaerobic conditions in a CO2-enriched growth medium, separating the bacteria from the resulting broth and isolating the hyaluronic acid from the remaining constituent of the broth.
Abstract: Hyaluronic acid, a polysaccharide, is prepared in high yield from streptococcus bacteria by fermenting the bacteria under anaerobic conditions in a CO2-enriched growth medium, separating the bacteria from the resulting broth and isolating the hyaluronic acid from the remaining constituent of the broth. The bacteria may be grown free of endotoxins by filtering all ingredients through a 10K Millipore (Reg. Trademark) filter prior to inoculation of the medium and subsequently maintaining pyrogen-free conditions. Separation of the microorganisms from the polysaccharide is facilitated by killing the bacteira with trichloroacetic acid. After removal of the bacterial cells and concentration of the higher molecular weight fermentation products, the hyaluronic acid is isolated and purified by precipitation, resuspension and reprecipitation.
TL;DR: It has been demonstrated that Dunaliella concentrates of up to 300-fold can be directly fermented to an identical pattern of mixed solvents and solvent yields were reduced by >50% when fermentations were performed in the presence of 2% NaCl.
Abstract: Five species of the genus Dunaliella (D. tertiolecta, D. primolecta, D. parva, D. bardawil, and D. salina) were examined for glycerol accumulation, growth rate, cell density, and protein and chlorophyll content. The suitability of each algal species for use as a fermentation substrate was judged according to glycerol accumulation and quantities of neutral solvents produced after sequential bacterial fermentations. When grown in 2 M NaCl, with 24 mM NaHCO3 or 3% CO2 at 28°C and with 10,000 to 15,000 lx of incident light on two sides of a glass aquarium, four of the five species tested produced ca. 10 to 20 mg of glycerol per liter of culture. Clostridium pasteurianum was found to convert an algal biomass mixture supplemented with 4% glycerol to ca. 16 g of mixed solvents (n-butanol, 1,3-propanediol, and ethanol) per liter. Acetone was not detected. Additionally, it has been demonstrated that Dunaliella concentrates of up to 300-fold can be directly fermented to an identical pattern of mixed solvents. Overall solvent yields were reduced by >50% when fermentations were performed in the presence of 2% NaCl. These results are discussed in terms of practical application in tropical coastal zones.
TL;DR: Factors that may initiate the metabolic transition for butanol production were investigated in batch cultures of Clostridium beijerinckii and it is speculated that a slowdown in metabolism, which may be brought about by several conditions, is mechanistically related to the onset ofbutanol production.
Abstract: Factors that may initiate the metabolic transition for butanol production were investigated in batch cultures of Clostridium beijerinckii (synonym, Clostridium butylicum) VPI 13436. Cultures maintained at pH 6.8 produced nearly as much butanol as those incubated without pH control, indicating that neither a change in the culture pH nor acid conditions per se are always required to initiate solvent formation. Acetate and butyrate levels at the onset of butanol production were dependent on the pH at which the cultures were maintained. Cultures maintained at pH 6.8 could be accelerated into solvent production by artificially lowering the pH to 5.0 or by the addition of acetate plus butyrate without a pH change (but neither acid alone was effective). Solvent production was associated with slower rates of growth and general metabolism, and it did not show a requirement for mature spore formation. We speculate that a slowdown in metabolism, which may be brought about by several conditions, is mechanistically related to the onset of butanol production. Extracts of solvent-producing cells contained acetoacetate decarboxylase activity as well as higher NADP+-linked butanol dehydrogenase and lower hydrogenase activities than extracts of acid-producing cells. Solvent production did not appear to involve an enhanced ability to catalyze H2 oxidation.
TL;DR: A computer‐aided methodology is developed for on‐line monitoring and control of cell growth in fed‐batch penicillin fermentation using a semidefined medium containing low corn steep liquor concentration.
Abstract: A computer-aided methodology is developed for on-line monitoring and control of cell growth in fed-batch penicillin fermentation using a semidefined medium containing low corn steep liquor concentration (5.7 g/L). Cell growth is monitored and controlled with the use of experimental correlation and carbon-balancing equatiions on a real-time basis throughout the fermentation. Through a combination of feed-forward and feedback control of sugar addition, residual glucose concentration in the broth was maintained below 1 g/L and cell-growth rate was kept at constant at preset vaiues. The accuracy and reproducibility of this technique are demonstrated. The use of real-time control of cell growth is expected to aid future investigations of this antibiotic fermentation.
TL;DR: Studies of bacterial physiology have provided new insights into the mechanisms of end-product inhibition and these may lead to reduced manufacturing costs for fermentation products such as ethanol, butanol, acetone and lactic acid.
Book•
01 Jan 1983
TL;DR: Baked Goods Wine and Brandy Beer Cheese Other Fermented Dairy Products Lactic Acid Fermentation of Cabbage and Cucumbers Olives Starter Cultures in Meat Production Vinegar Distilled Beverages Indigenous Fermented Foods.
Abstract: Baked Goods Wine and Brandy Beer Cheese Other Fermented Dairy Products Lactic Acid Fermentation of Cabbage and Cucumbers Olives Starter Cultures in Meat Production Vinegar Distilled Beverages Indigenous Fermented Foods Cocoa Fermentation Tea Manufacture Coffee Fermentation Fermented Feeds and Feed Supplements.
TL;DR: Clostridium stercorarium, a new species of anaerobic, sporeforming, thermophilic, saccharoclastic, cellulolytic bacteria, is described, and its temperature optimum is 65%C.
Abstract: Clostridium stercorarium, a new species of anaerobic, sporeforming, thermophilic, saccharoclastic, cellulolytic bacteria, is described. The colonies produced by these bacteria on cellobiose agar are 3 to 6 mm in diameter, cream colored, glossy, and umbonate with fiat, entire margins. Single cells are straight rods 0.7 to 0.8 by 2.7 to 7.7 µm, with oval terminal spores. Fermentation products from cellulose include hydrogen, carbon dioxide, ethanol, acetate, and lactate. The deoxyribonucleic acid base composition of the type strain of C. stercorarium, NCIB 11754, is 39 mol% guanine plus cytosine, and its temperature optimum is 65%C. The specific epithet refers to the source of the original isolate, rotting vegetation (a compost heap).
TL;DR: It could be shown that the synthesis of pyruvate decarboxylase is efficiently regulated by variations in the amount of PDC1 mRNA, which is affected by a number of different factors.
Abstract: The yeast PDC1 gene coding for the fermentative enzyme pyruvate decarboxylase was isolated. This DNA sequence was used to identify the corresponding messenger RNA by hybridization. It could be shown that the synthesis of pyruvate decarboxylase is efficiently regulated by variations in the amount of PDC1 mRNA. Very low levels of PDC1 mRNA were found in cells growing in a medium containing ethanol. Glucose addition to these cells leads to a rapid accumulation of PDC1 mRNA. The PDC1 mRNA levels found in different mutants and in cells growing in media containing carbon sources other than glucose or ethanol suggest that the amount of PDC1 mRNA in yeast cells is affected by a number of different factors.
TL;DR: A selective solvent pretreatment with alkaline–ethanol–water mixtures was examined for the delignification of cellulosic biomass under conditions where very little loss of fermentable carbohyrates results.
Abstract: Cellulose and hemicellulose in renewable biomass resources such as cornstover and wheat straw have been examined as substrates for the production of ethanol. A mixed culture of selected strains of Clostridium thermocellum and Clostridium thermosaccharolyticum are used to accomplish both the hydrolysis and fermentation of these carbohydrates in a single step. However, lignin and related phenolic materials are shown to diminish the rate, extent, and yield at which these carbohydrates can be utilized for ethanol production. In order to overcome this problem, a selective solvent pretreatment with alkaline-ethanol-water mixtures was examined for the delignification of cellulosic biomass under conditions where very little loss of fermentable carbohyrates results. Under optimal conditions, up to 67% of the initial lignin in cornstover can be extracted while 95% of the alpha-cellulose and pentosan carbohydrates remain insoluble. Subsequent mixed culture fermentation of the treated material has shown a 400% increase in the rate of degradation and greater than 85% utilization of the substrate. The effects of various extraction parameters on delignification kinetics and subsequent fermentation performance are discussed.
TL;DR: Organisms from cultures exhibiting delayed fermentation in the presence of sublethal concentrations of an herb, when subcultured into fresh media containing identical herb concentrations, initiated fermentation without delay, indicating development of resistance to the herb's effect.
Abstract: Increasing concentrations (0.5–8g/liter) of oregano, rosemary, sage, and thyme progressively delayed growth and acid production by Lactobacillus plantarum and Pediococcus acidilactici in a liquid medium. After the bacteriostatic activity was overcome, all four herbs strongly stimulated acid production. The relative inhibitory effect of the herbs toward both microorganisms was oregano ≫ rosemary = sage gt; thyme. L. plantarum was more resistant than P. acidilactici to the toxic effect of the herbs. Organisms from cultures exhibiting delayed fermentation in the presence of sublethal concentrations of an herb, when subcultured into fresh media containing identical herb concentrations, initiated fermentation without delay, indicating development of resistance to the herb's effect. Moreover, bacteria which had acquired a resistance to one herb were also resistant to the other three herbs.
TL;DR: It can be concluded that brewers yeast are tolerant to levels of ethanol previously associated only with winery and distilling yeasts, and that they do not require genetic manipulation or strain improvement to become tolerant to 14–16% ethanol.
Abstract: Supplementation of high gravity brewing worts with 0.8% yeast extract, 24 ppm ergosterol and 0.24% (v/v) Tween 80 can result in the production of >14% (v/v) alcohol at 14°C within 5 days. Unsupplemented worts require up to 2 weeks to end ferment. Overcoming nitrogenous and lipid nutritional deficiencies results in substantial increases in cell mass production, decreased fermentation times and increased ethanol. It can be concluded that brewers yeast are tolerant to levels of ethanol previously associated only with winery and distilling yeasts, and that they do not require genetic manipulation or strain improvement to become tolerant to 14–16% ethanol.
TL;DR: The bioconversion of sugars present in wood hemicellulose to 2,3-butanediol by Klebsiella pneumoniae grown on high sugar concentrations was investigated and final butanediol values were higher for cultures grown on an initial sugar concentration of 150 g/liter, particularly when the inoculum was first acclimatized to high sugar levels.
Abstract: The bioconversion of sugars present in wood hemicellulose to 2,3-butanediol by Klebsiella pneumoniae grown on high sugar concentrations was investigated When K pneumoniae was grown under finite air conditions in the presence of added acetic acid, 50 g of D-glucose and D-xylose per liter could be converted to 25 and 27 g of butanediol per liter, respectively The efficiency of bioconversion decreased with increasing sugar substrate concentrations (up to 200 g/liter) Butanediol production at low sugar substrate concentrations was less efficient when the organism was grown under aerobic conditions; however, final butanediol values were higher for cultures grown on an initial sugar concentration of 150 g/liter, particularly when the inoculum was first acclimatized to high sugar levels When a double fed-batch approach (daily additions of sugars together with yeast extract) was used under aerobic conditions, up to 88 and 113 g of combined butanediol and acetyl methyl carbinol per liter could be obtained from the utilization of 190 g of D-xylose and 226 g of D-glucose per liter, respectively
TL;DR: The separations method described in this article involves the use of solid materials to preferentially remove ethanol from fermentation broths using an experimental proprietary molecular sieve with hydrophobic properties and column breakthrough curves indicated very favorable kinetics.
Abstract: Industrialized nations face a critical problem in replacing the sources of liquid fuels that traditionally have been supplied by petroleum. One solution that has gained increasing support in this country is the use of ethanol produced by fermentation of renewable biomass as an extender in, or supplement to, gasoline for transportation fuel. Distillation, the present method of separating ethanol from the fermentation broth, is an energy-intensive one and frequently uses more energy than is available from the ethanol recovered. There are many investigations under way to find alternative, less energy-intensive techniques for the ethanol-water separation. The separations method described in this article involves the use of solid materials to preferentially remove ethanol from fermentation broths. Subsequent stripping of the ethanol from the sorbent with a dry gas reduces dramatically the energy required for the separation. Three solid sorbents have been investigated experimentally. Their sorption/desorption characteristics are described, and their incorporation in an ethanol recovery process is evaluated. Three sorbents were investigated: two commercially available divinylbenzene crosslinked polystyrene resins in bead form (one with a nominal surface area of 300 m(2)/g, the other with 750 m(2)/g) and an experimental proprietary molecular sieve with hydrophobic properties. Equilibrium adsorption isotherms for two of the sorbents were obtained at ambient temperature (21 degrees C) for ethanol-water solutions containing up to 12 wt. % ethanol. In addition, 40 degrees C isotherms were obtained for the polystyrene sorbents. Although different, the equilibrium isotherms for the sorbents indicated that ethanol could be preferentially sorbed from a dilute solution. Column breakthrough curves indicated very favorable kinetics. Desorption of the ethanol was readily effected with warm (60-80 degrees C), dry nitrogen.
TL;DR: A new Clostridium species is described that was isolated from a thermal, volcanic, algal-bacterial community via selective enrichment procedures with pectin as energy source and revealed a double-layered wall without the presence of an outer membranous layer.
Abstract: SUMMARY: A new Clostridium species is described that was isolated from a thermal, volcanic, algal-bacterial community via selective enrichment procedures with pectin as energy source. Clostridium thermosulfurogenes sp. nov. deposits elemental sulphur on the cell surface and in the culture medium from thiosulphate transformation. This species stained Gram-negative, but electron micrographs revealed a double-layered wall without the presence of an outer membranous layer. Thin sections displayed numerous internal membranes and sulphur granules were not discernible. The organism was motile and formed distinctly swollen sporangia with terminal, white-refractile, spherical spores. The temperature range for growth was >35 °C and <75 °C, the pH range was between 4.0 and 7.5. The DNA base composition was 32.6 < 0.04 mol% guanosine plus cytosine. Fermentable carbohydrates included pectin, starch, xylose, glucose, mannose, cellobiose, maltose, arabinose and sucrose. The doubling time on glucose or pectin was about 2 h. The production of ethanol, H2/CO2, acetate and lactate accounted for a balanced fermentation of glucose, whereas methanol and isopropanol were also produced during pectin fermentation. The taxonomic relationships of C. thermosulfurogenes to other thermophilic Clostridia and its biological role in a thermal microbial community are discussed.