Showing papers on "Fermentation published in 1982"

Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids II. Incomplete oxidation of propionate by Desulfobulbus propionicus gen. nov., sp. nov.

Abstract: A new type of sulfate-reducing bacteria with ellipsoidal to lemon-shaped cells was regularly enriched from anaerobic freshwater and marine mud samples when mineral media with propionate and sulfate were used. Three strains (1pr3, 2pr4, 3pr10) were isolated in pure culture. Propionate, lactate and alcohols were used as electron donors and carbon sources. Growth on H2 required acetate as a carbon source in the presence of CO2. Stoichiometric measurements revealed that oxidation of propionate was incomplete and led to acetate as an endproduct. Instead of sulfate, strain 1pr3 was shown to reduce sulfite and thiosulfate to H2S; nitrate also served as electron acceptor and was reduced to ammonia. With lactate or pyruvate, all three strains were able to grow without external electron acceptor and formed propionate and acetate as fermentation products. None of the strains contained desulfoviridin. In strain 1pr3 cytochromes of the b- and c-type were identified. Strain 1pr3 is described as type strain of the new species and genus, Desulfobulbus propionicus.

Intermediary Metabolism of Organic Matter in the Sediments of a Eutrophic Lake

Abstract: The rates, products, and controls of the metabolism of fermentation intermediates in the sediments of a eutrophic lake were examined. 14C-fatty acids were directly injected into sediment subcores for turnover rate measurements. The highest rates of acetate turnover were in surface sediments (0- to 2-cm depth). Methane was the dominant product of acetate metabolism at all depths. Simultaneous measurements of acetate, propionate, and lactate turnover in surface sediments gave turnover rates of 159, 20, and 3 μM/h, respectively. [2-14C]propionate and [U-14C]lactate were metabolized to [14C]acetate, 14CO2, and 14CH4. [14C]formate was completely converted to 14CO2 in less than 1 min. Inhibition of methanogenesis with chloroform resulted in an immediate accumulation of volatile fatty acids and hydrogen. Hydrogen inhibited the metabolism of C3-C5 volatile fatty acids. The rates of fatty acid production were estimated from the rates of fatty acid accumulation in the presence of chloroform or hydrogen. The mean molar rates of production were acetate, 82%; propionate, 13%; butyrates, 2%; and valerates, 3%. A working model for carbon and electron flow is presented which illustrates that fermentation and methanogenesis are the predominate steps in carbon flow and that there is a close interaction between fermentative bacteria, acetogenic hydrogen-producing bacteria, and methanogens.

Production and Tolerance of Ethanol in Relation to Phospholipid Fatty-acyl Composition in Saccharomyces cerevisiae NCYC 431

Abstract: Summary: Accumulation of ethanol in supernatants from anaerobic cultures of Saccharomyces cerevisiae NCYC 431 closely paralleled growth during the early exponential phase of batch growth, and continued after growth had ceased. During the 8–64 h period of the fermentation, the intracellular ethanol concentration was greater than the extracellular concentration. Ethanol was very rapidly extracted from organisms by washing with water. During growth up to 32 h, there was a progressive decrease in fatty-acyl unsaturation in phospholipids, and a corresponding proportional increase in saturation. Thereafter, the trend was very slightly reversed. Supplementing cultures with ethanol (0.5 or 1.0m) after 8h incubation retarded growth rate, while supplementation with 1.5 m-ethanol immediately stopped growth. In cultures supplemented with 0.5 or 1.0 m-ethanol, viability was not lowered, but supplementation with 1.5 m-ethanol caused a rapid decline in viability. Supplementation of cultures with ethanol at any of the three concentrations led to an increase in the proportion of mono-unsaturated fatty-acyl residues in cellular phospholipids, especially in C18 residues, which was accompanied by a decrease in the proportion of saturated residues.

Acetone and Butanol Production by Clostridium acetobutylicum in a Synthetic Medium.

Abstract: The effect of the component concentrations of a synthetic medium on acetone and butanol fermentation by Clostridium acetobutylicum ATCC 824 was investigated. Cell growth was dependent on the presence of Mg, Fe, and K in the medium. Mg and Mn had deleterious effects when in excess. Ammonium acetate in excess caused acid fermentation. The metabolism was composed of two phases: an acid phase and a solvent one. Low concentrations of glucose allowed the first phase only. The theoretical ratio of the conversion of glucose to solvents, which was 28 to 33%, was obtained with the following medium: MgSO4, 50 to 200 mg/liter; MnSO4, 0 to 20 mg/liter; KCl, 0.015 to 8 g/liter (an equivalent concentration of K+ was supplied in the form of KH2PO4 and K2HPO4); FeSO4, 1 to 50 mg/liter; ammonium acetate, 1.1 to 2.2 g/liter; para-aminobenzoic acid, 1 mg/liter; biotin, 0.01 mg/liter; glucose, 20 to 60 g/liter.

Effect of pH and butyrate concentration on the production of acetone and butanol by Clostridium acetobutylicum grown in continuous culture

Abstract: When Clostridium acetobutylicum was grown in continuous culture under glucose limitation at neutral pH and varying dilution rates the only fermentation products formed were acetate, butyrate, carbon dioxide and molecular hydrogen. The Y glucose max and (Y ATP max ) gluc exp values were 48.3 and 23.8 dry weight/mol, respectively. Acetone and butanol were produced when the pH was decreased below 5.0 (optimum at pH 4.3). The addition of butyric acid (20 to 80 mM) to the medium with a pH of 4.3 resulted in a shift of the fermentation from acid, to solvent formation.

Ethanol production by extractive fermentation

Abstract: The ideal method to produce a terminal metabolite inhibitor of cell growth and production is to remove and recover it from the fermenting broth as it formed. Extractive fermentation is achieved in the case of ethanol production by coupling both fermentation and liquid-liquid extraction, The solvent of extraction is 1-dodecanol (or a mixture 1-dedecanol, 1-tetradecanol); study of the inhibitory effect of primary aliphatic alcohols of different chain lengths shows that no growth is observed in the presence of alcohols which have between 2 and 12 carbons. This effect is suppressed when the carbon number is 12 or higher. A new reactor has been used-1 pulsed packed column. Pulsation is performed pneumatically. Porous material used as a package adsorbs the cells. The fermentation broth is pulsed in order to (1) increase the interfacial area between the aqueous phase and the dodecanol, (2) decrease gas holdup. Alcoholic fermentation, performed at 35 degrees C on glucose syrup, permits the total utilization of glucose solution of 409 g/L with a yeast which cannot-in classical process- completely use solutions with 200 g/L of glucose. The feasibility of a new method of fermentation coupling both liquid-liquid extraction and fermentation is demonstrated. Extension of this method is possible to any microbial production inhibited by its metabolite excretion.

Fermentation of Trihydroxybenzenes by Pelobacter acidigallici gen. nov. sp. nov., a New Strictly Anaerobic, Non-Sporeforming Bacterium

Abstract: Five strains of rod-shaped, Gram-negative, non-sporing, strictly anaerobic bacteria were isolated from limnic and marine mud samples with gallic acid or phloroglucinol as sole substrate. All strains grew in defined mineral media without any growth factors; marine isolates required salt concentrations higher than 1% for growth, two freshwater strains only thrived in freshwater medium. Gallic acid, pyrogallol, 2,4,6-trihydroxybenzoic acid, and phloroglucinol were the only substrates utilized and were fermented stoichiometrically to 3 mol acetate (and 1 mol CO2) per mol with a growth yield of 10g cell dry weight per mol of substrate. Neither sulfate, sulfur, nor nitrate were reduced. The DNA base ratio was 51.8% guanine plus cytosine. A marine isolate, Ma Gal 2, is described as type strain of a new genus and species, Pelobacter acidigallici gen. nov. sp. nov., in the family Bacteroidaceae. In coculture with Acetobacterium woodii, the new isolates converted also syringic acid completely to acetate. Cocultures with Methanosarcina barkeri converted the respective substrates completely to methane and carbon dioxide.

Continuous production of acetone and butanol by Clostridium acetobutylicum in a two-stage phosphate limited chemostat

Abstract: When Clostridium acetobutylicum was grown in continuous culture under phosphate limitation (0.74 mM) at a pH of 4.3, glucose was fermented to butanol, acetone and ethanol as the major products. At a dilution rate of D=0.025 h−1 and a glucose concentration of 300 mM, the maximal butanol and acetone concentrations were 130 mM and 74 mM, respectively. 20% of the glucose remained in the medium. On the basis of these results a two-stage continuous process was developed in which 87.5% of the glucose was converted into butanol, acetone and ethanol. The cells and minor amounts of acetate and butyrate accounted for the remaining 12.5% of the substrate. The first stage was run at D=0.125 h−1 and 37° C and the second stage at D=0.04 h−1 and 33° C. High yields of butanol and acetone were also obtained in batch culture under phosphate limitation.

Solid Substrate Fermentations

Abstract: Publisher Summary The solid-state fermentation refers to any fermentation that takes place on solid or semisolid substrate or that occurs in a nutritionally inert solid support, which provides some advantage to the microorganism with respect to access to nutrients. In a solid-state fermentation, several factors must be taken into consideration to achieve high efficiency of the overall process. Some of the general characteristics include: the solid substrate must be in a form to allow free circulation of air, usually the only other medium component required is water, and control of temperature is sometimes critical. Moisture content of the solid substrate is an important factor during microbial growth in a solid-state fermentation process. There are many advantages of the solid-state fermentation processes over the conventional stirred tank system on both laboratory and large scale. Some of the advantages for work involving fungi are—the medium is relatively simple, the conditions under which the fungus grows are more like the conditions in its natural habitat, and the desired product may be readily extracted from the vessel by addition of solvent directly.

Salient Biochemical Characters of Actinobacillus actinomycetemcomitans

Abstract: A total of 136 strains of Actinobacillus actinomycetemcomitans were studied for 135 features. All isolates were small nonmotile capnophilic gram-negative rods which grew with no requirement of X or V growth factors. They all decomposed hydrogen peroxide, were oxidase-negative and benzidine-positive, reduced nitrate, produced strong alkaline and acid phosphatases, and fermented fructose, glucose and mannose. Variable fermentation results were obtained with dextrin, maltose, mannitol and xylose. Some isolates produced small amounts of gas. Representative strains of Haemophilus aphrophilus were morphologically and biochemically quite similar to A. actinomycetemcomitans. Characters which should prove to be useful to identify and distinguish these two species include catalase reaction. fermentation of lactose, starch, sucrose and trehalose, and resistance to sodium fluoride. This information allows a rapid diagnosis by species and may be helpful in studies of infections involving these organisms.

Alcohol conversions by desulfobulbus-propionicus lindhorst in the presence and absence of sulfate and hydrogen

Abstract: Ethanol was rapidly degraded to mainly acetate in anaerobic freshwater sediment slurries. Propionate was produced in small amounts. Desulfovibrio species were the dominant bacteria among the ethanol-degrading organisms. The propionate-producing Desulfobulbus propionicus came to the fore under iron-limited conditions in an ethanol-limited chemostat with excess sulfate inoculated with anaerobic intertidal freshwater sediment. In the absence of sulfate, ethanol was fermented by D. propionicus Lindhorst to propionate and acetate in a molar ratio of 2.0.l-Propanol was intermediately produced during the fermentation of ethanol. In the presence of H2 and CO2, ethanol was quantitatively converted to propionate. H2-plus sulfate-grown cells of D. propionicus Lindhorst were able to oxidize l-propanol and l-butanol to propionate and butyrate respectively with the concomitant reduction of acetate plus CO2 to propionate. Growth was also observed on acetate alone in the presence of H2 and CO2 D. propionicus was able to grow mixotrophically on H2 plus an organic compound. Finally, a brief discussion has been given of the ecological niche of D. propionicus in anaerobic freshwater sediments.

Fermentation and Anaerobic Respiration by Rhodospirillum rubrum and Rhodopseudomonas capsulata

Abstract: Rhodospirillum rubrum and Rhodopseudomonas capsulata were able to grow anaerobically in the dark either by a strict mixed-acid fermentation of sugars or, in the presence of an appropriate electron acceptor, by an energy-linked anaerobic respiration Both species fermented fructose without the addition of accessory oxidants, but required the initial presence of bicarbonate before fermentative growth could begin Major products of R rubrum fermentation were succinate, acetate, propionate, formate, hydrogen, and carbon dioxide; R capsulata produced major amounts of lactate, acetate, succinate, hydrogen, and carbon dioxide R rubrum and R capsulata were also capable of growing strictly through anaerobic, respiratory mechanisms Nonfermentable substrates, such as succinate, malate, or acetate, supported growth only in the presence of an electron acceptor such as dimethyl sulfoxide or trimethylamine oxide Carbon dioxide and dimethyl sulfide were produced during growth of R rubrum and R capsulata on succinate plus dimethyl sulfoxide Molar growth yields from cultures grown anaerobically in the dark on fructose plus dimethyl sulfoxide were 38 to 46 times higher than values obtained from growth on fructose alone and were 56 to 60% of the values obtained from aerobic, respiratory growth with fructose Likewise, molar growth yields from anaerobic, respiratory growth conditions with succinate plus dimethyl sulfoxide were 51 to 54% of the values obtained from aerobic, respiratory growth with succinate The data indicate that dimethyl sulfoxide or trimethylamine oxide as a terminal oxidant is approximately 33 to 41% as efficient as O2 in conserving energy through electron transport-linked respiration

Involvement of oxygen-sensitive pyruvate formate-lyase in mixed-acid fermentation by Streptococcus mutans under strictly anaerobic conditions.

Abstract: Streptococcus mutans JC2 produced formate, acetate, ethanol, and lactate when suspensions were incubated with an excess of galactose or mannitol under strictly anaerobic conditions. The galactose- or mannitol-grown cell suspensions produced more formate, acetate, and ethanol than the glucose-grown cells even when incubated with glucose. The levels of lactate dehydrogenase and fructose 1,6-bisphosphate were not significantly different in these cells, but the level of pyruvate formate-lyase was higher in the galactose- or mannitol-grown cells, and that of triose phosphate was lower in the galactose-grown cells. This suggests that the regulation of pyruvate formate-lyase may play a major role in the change of the fermentation patterns. The cells of S. mutans grown on glucose produced a significant amount of volatile products even in the presence of excess glucose under strictly anaerobic conditions. However, when the anaerobically grown cells were exposed to air, only lactate was produced from glucose. When cells were anaerobically grown on mannitol and then exposed to air for 2 min, only trace amounts of fermentation products were formed from mannitol under anaerobic conditions. It was found that the pyruvate formate-lyase in the cells was inactivated by exposure of the cells to air.

Mechanisms of appearance of the Pasteur effect in Saccharomyces cerevisiae: inactivation of sugar transport systems.

Abstract: Saccharomyces cerevisiae does not show a noticeable Pasteur effect (activation of sugar catabolism by anaerobiosis) when growing with an excess of sugar and nitrogen source, but it does do so after exhaustion of the nitrogen source in the medium (resting state). We have found that this different behavior of growing and resting S. cerevisiae seems due to differences in the contribution of respiration to catabolism under both states. Growing S. cerevisiae respired only 3 to 20% of the catabolized sugar, depending on the sugar present; the remainder was fermented. In contrast, resting S. cerevisiae respired as much as 25 to 100% of the catabolized sugar. These results suggest that a shift to anaerobiosis would have much greater energetic consequences in resting than in growing S. cerevisiae. In resting S. cerevisiae anaerobiosis would strongly decrease the formation of ATP; as a consequence, various regulatory mechanisms would switch on, producing the observed increase of the rate of glycolysis. The greater significance that respiration reached in resting cells was not due to an increase of the respiratory capacity itself, but to a loss of fermentation which turned respiration into the main catabolic pathway. The main mechanism involved in the loss of fermentation observed during nitrogen starvation was a progressive inactivation of the sugar transport systems that reduced the rate of fermentation to less than 10% of the value observed in growing cells. Inactivation of the sugar transports seems a consequence of the turnover of the sugar carriers whose apparent half-lives were 2 to 7 h.

Studies on immobilized Saccharomyces cerevisiae. I. Analysis of continuous rapid ethanol fermentation in immobilized cell reactor.

Abstract: Rapid fermentation of cane molasses into ethanol has been studied in batch, continuous (free-cell cell-immobilized systems) by a strain of Saccharomyces cerevisiae at temperature 30/sup 0/C and pH 5.0. The maximum productivity of ethanol obtained in immobilized system was 28.6 g L/sup -1/ h/sup -1/. The cells were immobilized by natural mode on a carrier of natural origin and retention of 0.132 g cells/g carrier was achieved. The immobilized-cell column was operated continuously at steady state over a period of 35 days. Based on the parameter data monitored from the system, mathematical analysis has been made and rate equations proposed, and the values of specific productivity of ehtanol and specific growth rate for immobilized cells computed. It has been established that immobilized cells exhibit higher specific rate of ethanol formation compared to free cells but the specific growth rate appears to be comparatively low. The yield of ethanol in the immobilized-cell system is also higher than in the free-cell system.

Ester Concentration Differences in Wine Fermented by Various Species and Strains of Yeasts

Abstract: Fourteen pure-culture wine yeasts were found to produce white wines with significantly different individual ester concentrations. The esters quantified, by glass capillary gas chromatography, were isoamyl acetate (including active amyl acetate), ethyl hexanoate, hexyl acetate, ethyl octanoate, 2-phenethyl acetate, and ethyl decanoate. The complex relationships for each ester due to the yeast used for fermentation are illustrated. From analysis of variance of the total-ester content in the wines, only Saccharomyces cerevisiae (U.C.D. Enology 586) was found to be significantly different (.01 level) from the other yeasts examined.

Propionigenium modestum gen. nov. sp. nov. a new strictly anaerobic, nonsporing bacterium growing on succinate

Abstract: From marine and freshwater mud samples and from human saliva new strictly anaerobic, Gram-negative, nonsporeforming bacteria were isolated growing with succinate as sole source of carbon and energy. All strains grew in defined mineral media containing at least 1% sodium chloride. Succinate was stoichiometrically transformed to propionate und carbon dioxide; the growth yield varied between 2.1 and 2.4 g cell dry weight per mol of succinate fermented. In addition to succinate, only fumarate, l-aspartate, l-malate, oxaloacetate and pyruvate, were utilized and were stoichiometrically fermented to propionate and acetate. Yeast extract was not fermented but enhanced growth rates and yields. Neither sulfate, sulfur, nor nitrate were reduced. The DNA base ratio was 33.9±0.3 mol % guanine plus cytosine. A marine isolate, strain Gra Succ 2, is described as type strain of a new species, Propionigenium modestum gen. nov. sp. nov., in the family Bacteroidaceae.

Fermentation of Cellulose to Methane and Carbon Dioxide by a Rumen Anaerobic Fungus in a Triculture with Methanobrevibacter sp. Strain RA1 and Methanosarcina barkeri.

Abstract: The fermentation of cellulose by a rumen anaerobic fungus in the presence of Methanobrevibacter sp. strain RA1 and Methanosarcina barkeri strain 227 resulted in the formation of 2 mol each of methane and carbon dioxide per mol of hexose fermented. Coculture of the fungus with either Methanobrevibacter sp. or M. barkeri produced 0.6 and 1.3 mol of methane per mol of hexose, respectively. Acetate, formate, ethanol, hydrogen, and lactate, which are major end products of cellulose fermentation by the fungus alone, were either absent or present in very low quantities at the end of the triculture fermentation (

Direct Fermentation of d-Xylose to Ethanol by Kluyveromyces marxianus Strains.

Abstract: Eight strains of Kluyveromyces marxianus were screened, and all of them were found to ferment the aldopentose d-xylose directly to ethanol under aerobic conditions. One of these strains, K. marxianus SUB-80-S, was grown in a medium containing 20 g of d-xylose per liter, and the following results were obtained: maximum ethanol concentration, 5.6 g/liter; ethanol yield, 0.28 g of ethanol per g of d-xylose (55% of theoretical); maximum specific growth rate, 0.12 h−1; 100% d-xylose utilization was completed in 48 h.

Isolation of ethanol-tolerant mutants of yeast by continuous selection

Abstract: The ethanol tolerance of Saccharomyces species is an important constraint on the efficiency of the industrial production of ethanol by fermentation. The alcohol reduces the viability, growth rate and fermentation rate of the producing organism. The complexity of the effect make it difficult to isolate tolerant mutants by simple agar plate screening regimes. We have therefore turned to continuous selection in an attempt to isolate such mutants.

Enhanced Production of 2,3-Butanediol by Klebsiella pneumoniae Grown on High Sugar Concentrations in the Presence of Acetic Acid.

Abstract: The bioconversion of sugars present in wood hemicellulose to 2,3-butanediol (hereafter referred to as butanediol) by Klebsiella pneumoniae grown on high initial concentrations (up to 10%) of sugars was investigated. Initial fermentation studies with a chemically defined medium suggested that sugar levels in excess of 2% could not be utlized even when a higher inoculum size (5 to 10%) was used. The addition of nutrient supplements, viz., yeast extract, urea, ammonium sulfate, and trace elements resulted in a 10 to 50% increase in butanediol yields, although sugar utilization remained incomplete. The concentration of end products normally found at the termination of fermentation was shown to be noninhibitory to growth and substrate utilization. Acetic acid was inhibitory at concentrations above 1%, although growth and butanediol yield were stimulated in cultures supplemented with lower levels of acetic acid. The efficient utilization of 4% substrate concentrations of d-glucose and d-xylose was achieved, resulting in butanediol yields of 19.6 and 22.0 g/liter, respectively.

Fermentation of D-xylose, xylitol, and D-xylulose by yeasts

Abstract: Fifteen yeasts which can assimilate D-xylose were examined for the ability to convert this pentose to ethanol. In six of the seven genera investigated the conversion was enhanced when air had access to the medium. Therefore, the ability to convert D-xylose to ethanol under these conditions is probably common among yeasts. Growth under the same conditions on xylitol, a putative catabolite of D-xylose, led to only traces of ethanol. The effects of growth on another putative catabolite, D-xylose, were complex, but some of the strains which were among the better producers of ethanol from D-xylose produced less from D-xylulose.

Lipid metabolism and the regulation of volatile ester synthesis in saccharomyces cerevisiae

Abstract: The specific rates at which ethyl acetate and iso-amyl acetate are produced by yeast increase markedly at that point in fermentation where syntheses of lipids (ie saturated fatty acids and squalene) stop An increase in the acetyl-CoA: CoASH ratio, or a reduced availability of substrates (fatty acyl-CoAs) for acyl transferases, are possible reasons for such a stimulation of ester synthesis Increased rates of ester production are not sustained but contribute significantly (ca 30% for ethyl acetate) to the total concentration of acetate esters in beer fermented from 1·040 all-malt wort Addition of linoleic acid (50 mg litre−1) suppresses the induction of ester synthesis and reduces overall formation of both ethyl and iso-amyl acetates by ca 80% Possibly, linoleic acid exerts these effects either by directly inhibiting the activity of an ester-synthesising enzyme, or by allowing alternative use of acetyl-CoA for the synthesis of saturated fatty acids