Showing papers on "Fermentation published in 1976"
327 citations
TL;DR: It was found that the intracellular ethanol concentration reached a level of approximately 2 X 10(11) ethanol molecules/cell in the first 30 min of fermentation at 30 C, which would appear to be normal and that this level does not damage either cell viability or ADH activity.
Abstract: Whereas "rapid fermentation" of diluted clover honey (25 degrees Brix) fortified with yeast nutrients using 8 X 10(8) brewers' yeast cells per ml resulted in an ethanol content of 9.5% (wt/vol; 12% vol/vol) in 3 h at 30 C, death rate of the yeast cells during this period was essentially logarithmic. Whereas 6 h was required to reach the same ethanol content at 15 C, the yeast cells retained their viability. Using a lower cell population (6 X 10(7) cells/ml), a level at which the fermentation was no longer "rapid," the yeast cells also retained their viability at 30 C. Ethanol added to the medium was much less lethal than the same or less quantities of ethanol produced by the cell in "rapid fermentation." It was considered possible that ethanol was produced so rapidly at 30 C that it could not diffuse out of the cell as rapidly as it was formed. The hypothesis was postulated that ethanol accumulating in the cell was contributing to the high death rate at 30 C. It was found that the intracellular ethanol concentration reached a level of approximately 2 X 10(11) ethanol molecules/cell in the first 30 min of fermentation at 30 C. At 15 C, with the same cell count, intracellular ethanol concentration reached a level of approximately 4 X 10(10) ethanol molecules/cell and viability remained high. Also, at 30 C with a lower cell population (6 X 10(7) cells/ml), under which conditions fermentation was no longer "rapid," intracellular ethanol concentration reached a similar level (4 X 10(10) molecules ethanol/cell) and the cells retained their viability. Alcohol dehydrogenase (ADH) lost its activity in brewers' yeast under conditions of "rapid fermentation" at 30 C but retained its activity in cells under similar conditions at 15 C. ADH activity was also retained in fermentations at 30 C with cell populations of 6 X 10(7)/ml. It would appear that an intracellular level of about 5 X 10(10) ethanol molecules/cell is normal and that this level does not damage either cell viability or ADH activity. Higher intracellular ethanol concentrations, such as 2 X 10(11) molecules ethanol/cell (a fourfold increase in intracellular ethanol concentration), are accompanied by inactivation of ADH and loss of cell viability.
225 citations
TL;DR: Effects of amino acids upon microbial growth, optimum ratio of nonprotein to amino acid nitrogen for microbialgrowth, and incorporation of amino acid into microbial cells were determined with washed cell suspension in vitro as were rumen microbial cells.
180 citations
TL;DR: The inter-relationships of organic acid and amino-acid metabolism, yeast growth and formation of fusel alcohols are discussed.
Abstract: The acids of alcoholic beverages are largely those present in the raw materials but the concentrations of some may be changed by yeast action during fermentation. In addition a number of other acids are formed by the yeasts often as by-products of main metabolic pathways. The inter-relationships of organic acid and amino-acid metabolism, yeast growth and formation of fusel alcohols are discussed.
130 citations
TL;DR: Preliminary process design and cost studies are developed for industrial scale fermentations to produce ethanol and torula yeast from sugars obtained by enzymatic hydrolysis of newsprint.
Abstract: Ethanol fermentation studies were conducted with Saccharomyces cerevisiae ATCC "4126, to determine the optimal conditions of oxygen tension and feed sugar concentration. In long-term continuous culture maximum ethanol production was found to occur at 0.07 mmHg oxygen tension and 10% glucose feed concentration. Preliminary process design and cost studies are developed for industrial scale fermentations to produce ethanol and torula yeast from sugars obtained by enzymatic hydrolysis of newsprint.
117 citations
TL;DR: Small amounts of amino acids to a diet containing urea as the sole nitrogen source improved considerably rumen microbial protein yields and rates of microbial growth, volatile fatty acid production, and effects of amino acid additions upon microbial nitrogen yields were highest right after feeding and decreased with time after feeding.
116 citations
TL;DR: Applying Green's theorem to the maximization problem was proposed, and it succeeded in determining the feed rate of the substrate that maximized the production rate ofThe desired product.
Abstract: This work is concerned with the optimization study of the semibatch fermentation by which an amino acid is produced. The particular fermentation studied is the synthesis of lysine by the auxotrophic mutant. Applying Green's theorem to the maximization problem was proposed, and it succeeded in determining the feed rate of the substrate that maximized the production rate of the desired product.
106 citations
TL;DR: It is concluded that the environment at birth is important in determining the fermentative ability of the stomach flora and that if lactic acid is produced in large amounts in the stomach, it may partly or completely inhibit acidification by HC1.
Abstract: 1. The contribution to acidification of the stomach contents of pigs by hydrochloric acid secretion or by lactic acid produced by fermentation was studied in fifteen suckling pigs from six litters born and reared either in a ‘conventional’ environment or in an isolated ‘clean’ environment. Sequential samples of stomach contents obtained during periods of up to 24 h were analysed for their chloride and lactic acid contents, pH and total titratable acidity. These values gave a measure of organic and inorganic acids respectively.2. Six pigs from two litters born and reared in a ‘clean’ environment had acid secretion in the stomach at 2 d of age, and the concentrations of lactic acid in stomach contents remained low (0-40 mmol/1) throughout the suckling period.3. Eight pigs from three litters born and reared in a ‘conventional’ environment, and a ninth pig born in this environment but moved to the ‘clean’ environment at 24 h of age, had lactic acid in concentrations of up to 250 mmol/l in stomach contents within the 1st week of life. The pattern of lactic acid production (and hence the acidity of stomach contents) was governed by the frequency of suckling.4. Both between- and within-litter variation in the age of onset of HCl secretion was evident in the group reared in a ‘conventional’ environment, and when HCl secretion did occur it was usually accompanied by a reduction in lactic acid production.5. It is concluded: (I) that the environment at birth is important in determining the fermentative ability of the stomach flora; (2) that if lactic acid is produced in large amounts in the stomach, it may partly or completely inhibit acidification by HCl.
104 citations
TL;DR: The results indicate that the ATP required for maintaining the yeast alive, what would be considered maintenance energy "sensu stricto", is only a minor proportion of the ATP spent in non net-biosynthetic functions during growth.
96 citations
TL;DR: Under aerobic and substrate‐limiting conditions, where the sugar substrate was fed incrementally, the growth pattern of the yeast cells was found to be uniform, as indicated by a constant respiratory quotient during the entire growing period.
Abstract: Saccharomyces cerevisiae was grown under aerobic and substrate-limiting conditions for efficient biomass production. Under these conditions, where the sugar substrate was fed incrementally, the growth pattern of the yeast cells was found to be uniform, as indicated by a constant respiratory quotient during the entire growing period. The effect of carbon dioxide was investigated by replacing portions of the nitrogen in the air stream with carbon dioxide, while maintaining the oxygen content at the normal 20% level, so that identical oxygen transfer rate and atmospheric pressure were maintained for all experiments with different partial pressures of carbon dioxide. Inhibition of yeast growth was negligible below 20% CO2 in the aeration mixture. Slight inhibition was noted at the 40% CO2 level and significant inhibition was noted above the 50% CO2 level, corresponding to 1.6 X 10(-2)M of dissolved CO2 in the fermentor broth. High carbon dioxide content in the gas phase also inhibited the fermentation activity of baker's yeast.
77 citations
TL;DR: The results suggest that the more rapid acid development that took place when a mixed yogurt starter culture was grown in milk containing prehydrolyzed lactose was the result of a more rapid and efficient utilization of carbohydrate by S. thermophilus when free glucose in addition to lactosewas available for fermentation.
Abstract: The mechanism responsible for an increased rate of acid production when yogurt starter cultures are grown in milk treated with lactase enzyme was investigated by studying carbohydrate utilization and acid development by a pure culture of Streptococcus thermophilus and a mixed yogurt starter culture consisting of S. thermophilus and Lactobacillus bulgaricus. In milk containing glucose, galactose, and lactose, glucose and lactose (but not free galactose) were fermented. Fermentation of lactose in control milk was accompanied by the release of free galactose, with the result that carbohydrate utilization was less efficient than in treated milk. This phenomenon also occurred when lactose was fermented by S. thermophilus in broth culture. Carbohydrate utilization by the mixed yogurt culture was more rapid when the lactose in milk was partially prehydrolyzed. Our results suggest that the more rapid acid development that took place when a mixed yogurt starter culture was grown in milk containing prehydrolyzed lactose was the result of a more rapid and efficient utilization of carbohydrate by S. thermophilus when free glucose in addition to lactose was available for fermentation. The evidence presented also suggests that uptake and utilization of glucose and lactose by S. thermophilus are different in broth and milk cultures.
TL;DR: Dilution rate and the efficiency of synthesis of microbial protein in vivo were increased and there was an increased flow of total amino acids into the duodenum with artificial saliva infusion.
Abstract: Artificial saliva (4 litres/day) was infused into the rumen of sheep fed a semi-purified diet at hourly intervals. Dilution rate and the efficiency of synthesis of microbial protein in vivo were increased. The pattern of rumen fermentation was altered; the molar proportion of propionic acid decreased (32–20%) and acetic acid increased (58–66%) with infusion, and there was an increased flow of total amino acids into the duodenum.
TL;DR: In this article, the relative significance of factors which cause pH to decrease during fermentation has been investigated, using eleven yeast strains and finding that approximately 30% of the increase in hydrogen ion concentration cannot be attributed to known causes; direct excretion of hydrogen ions may be responsible.
Abstract: The relative significance of factors which cause pH to decrease during fermentation has been investigated, using eleven yeast strains. Organic acid excretion and absorption of basic amino acids both have substantial effects: solution of carbon dioxide and absorption of primary phosphate contribute to a small extent. Buffering capacity, over the pH range 4 to 5, increases slightly during fermentation. Approximately 30% of the increase in hydrogen ion concentration cannot be attributed to known causes; direct excretion of hydrogen ions may be responsible. Fermentation with yeast propagated in semi-aerobic conditions rather than in fermentors gives beers of lower pH and increased organic acid content, but the latter factor is not in itself sufficient to account for the pH difference.
TL;DR: The data support the proposition that for ethylene to stimulate respiration the capacity for cyanide-resistant respiration must be present and enhance both respiration and aerobic glycolysis in cherimoya fruits with no buildup of lactate and ethanol and with an increase in the level of ATP.
Abstract: The effects of cyanide and ethylene, respectively, were studied on the respiration of a fully cyanide-sensitive tissue-the fresh pea, a slightly cyanide-sensitive tissue-the germinating pea seedling, and a cyanide-insensitive tissue-the cherimoya fruit. Cyanide inhibition of both fresh pea and pea seedling respiration was attended by a conventional Pasteur effect where fermentation was enhanced with an accumulation of lactate and ethanol and a change in the level of glycolytic intermediates indicative of the activation of phosphofructokinase and pyruvate kinase accompanied by a sharp decline in ATP level. In these tissues, ethylene had little or no effect on the respiration rate, or on the level of glycolytic intermediates or ATP. By contrast, ethylene as well as cyanide enhanced both respiration and aerobic glycolysis in cherimoya fruits with no buildup of lactate and ethanol and with an increase in the level of ATP. The data support the proposition that for ethylene to stimulate respiration the capacity for cyanide-resistant respiration must be present.
TL;DR: The rate of heat evolution in mycelial fermentations for novobiocin and cellulase production with media containing noncellular solids was measured by an in situ dynamic calorimetric procedure, demonstrating the validity of this technique by closing the overall material and energy balances.
Abstract: The rate of heat evolution (kcal/liter-hr) in mycelial fermentations for novobiocin and cellulase production with media containing noncellular solids was measured by an in situ dynamic calorimetric procedure. Thermal data so obtained have proved significant both in monitoring cell concentration during the trophophase (growth phase) and in serving as a physiological variable in the fermentation process. The validity of this technique has been demonstrated by closing the overall material and energy balances. The maintenance energy in a batch fermentation can be calculated by integrating heat evolution data. This integration method is applicable to a fermentation lacking a precise cell growth curve. The maintenance coefficient, obtained for the novobiocin fermentation by Streptomyces niveus, is equal to 0.028 g glucose equivalent/g cell-hr. The production of novobiocin in the idiophase (production phase) also correlates well with the amount of energy catabolized for maintenance and this results in an observed conversion yield of glucose to novobiocin of 11.8 mg of novobiocin produced per gram of glucose catabolized. A new physiological variable, kilocalories of heat evolved per millimole of oxygen consumed, has been proposed to monitor the state of cells during the fermentation. This method may provide a simple way to monitor on-line shifts in the efficiency of cell respiration and changes in growth yields during a microbial process.
TL;DR: A facultatively anaerobic spirochete isolated from a high-salinity pond grew optimally when 0.75 M NaCl, 0.2 M MgSO4, and 0.01 M CaCl2 were present in media containing yeast extract, peptone, and a carbohydrate.
Abstract: A facultatively anaerobic spirochete isolated from a high-salinity pond grew optimally when 0.75 M NaCl, 0.2 M MgSO4, and 0.01 M CaCl2 were present in media containing yeast extract, peptone, and a carbohydrate. The organism failed to grow when any one of these three salts was omitted from the medium. Aerobically-grown colonies of the spirochete were red, whereas anaerobically-grown colonies showed no pigmentation. Non-pigmented mutants of the spirochete were isolated. The spirochete used carbohydrates, but not amino acids, as energy sources. Glucose was fermented to CO2, H2, ethanol, acetate, and a small amount of lactate. Determinations of radioactivity in products formed from glucose-1-14C and enzymatic assays indicated that glucose was dissimilated to pyruvate mainly via the Embden-Meyerhof pathway. Pyruvate was metabolized through a clostridial-type clastic reaction. Cells growing aerobically performed an incomplete oxidation of glucose mainly to CO2 and acetate. Comparison of aerobic and anaerobic growth yields indicated that oxidative phosphorylation occurred in cells growing aerobically. The guanine + cytosine content of the DNA of the spirochete was 62 moles %. It is proposed that the spirochete described herein be considered a new species and that it be named Spirochaeta halophila.
Journal Article•
TL;DR: Chemostat cultures of E. coli K-12 revealed that the metabolic change from respiration to aerobic fermentation can be obtained with increasing specific growth rate at low glucose input concentration, or increasing glucose input concentrations at low Specific growth rate.
Abstract: Chemostat cultures of E. coli K-12 revealed that the metabolic change from respiration to aerobic fermentation can be obtained with increasing specific growth rate at low glucose input concentration (0.1%), or increasing glucose input concentrations at low specific growth rate (0.1 h-1). Both effects do not affect biomass formation. The metabolic change is not related to a pathway switch of glucose utilization. The increase in specific growth rate causes suppression of succinate dehydrogenase, and NADH oxidase, whereas glucose increases cause suppression of succinate dehydrogenase, cytochrome a and 2-ketoglutarate dehydrogenase. Both phenomena are reflected in the specific oxygen uptake rate, specific carbon dioxide production rate and respiratory quotient values. Growth limitation could be related to a maximal glucose uptake rate of the cell and thus constitutes an entirely different effect caused by high glucose input concentration.
Patent•
12 May 1976TL;DR: In this article, a system for treatment of biochemical waste such as activated sludges, the waste is subjected to anaerobic stabilization processes, which include two phases of an acid fermentation and a methane fermentation effected in separate reactors.
Abstract: In a system for treatment of biochemical waste such as activated sludges, the waste is subjected to anaerobic stabilization processes, which include two phases of an acid fermentation and a methane fermentation effected in separate reactors. The waste after the acid fermentation is then separated into a liquid effluent for the methane fermentation and a waste sludge. The waste sludge which may cause secondary environmental pollution is re-treated within the anaerobic stabilization processes without withdrawing from the system.
TL;DR: In this article, conditions for small-scale preparation of soy-sauce are described, and the first stage of the fermentation, growing the mould Aspergillus oryzae on a mixture of soy beans and wheat flour, followed standard procedures.
Abstract: Summary
Conditions for the small-scale preparation of soy-sauce are described. the first stage of the fermentation, growing the mould Aspergillus oryzae on a mixture of soy beans and wheat flour, followed standard procedures. In the second stage, the soy mash or moromi stage, a variety of conditions were tested. Results showed that a two-step fermentation occurs, first lactic acid bacteria, then yeast growing in the mash. Good yeast growth in the very salty mash depends upon the provision of acidic conditions.
TL;DR: A simple and efficient process for the production of a ruminant feed supplement, rich in crude protein, by bacterial fermentation of cheese whey has been developed, and 40 tons of concentrated product were produced fro animal feeding trials, without ever encountering putrefactive spoilage.
Abstract: A simple and efficient process for the production of a ruminant feed supplement, rich in crude protein (defined as total N X 6.25), by bacterial fermentation of cheese whey has been developed. The lactose in unpasteurized whey is fermented to lactate acid by Lactobacillus bulgaricus at a temperature of 43 degrees C and pH 5.5. The lactic acid produced is continually neutralized with ammonia to form ammonium lactate. The fermented product is concentrated by evaporation to a solids content of about 70% and adjusted to pH 6.8 with additional ammonia. The concentrated product contains about 55% crude protein. Approximately 6 to 8% of the crude protein is derived from bacterial cells. 17% from whey proteins, and 75 to 77% from ammonium lactate. The efficiency of conversion of lactose to lactic acid usually exceeds 95%. The fermentation time is greatly reduced upon the addition of 0.2% yeast extract or 0.1% corn steep liquor as a source of growth factors. Whey containing lactose at concentrations up to 7% can be fermented efficiently, but at higher concentrations lactose is fermented incompletely. The process has been scaled up to a pilot plant level, and 40 tons of concentrated product were produced fro animal feeding trials, without ever encountering putrefactive spoilage.
TL;DR: Physico-chemical characterization revealed that herbicidins are new antibiotics having an adenine nucleoside moiety in their structures.
Abstract: Herbicidins were produced in submerged fermentation by Streptomyces saganonensis. Isolation of the antibiotics from the culture broth was performed by adsorption on resinous adsorbent followed by elution with aqueous acetone. Herbicidins A and B were separated from each other by counter-current distribution on a Ronor column or by silica gel chromatography. Physico-chemical characterization revealed that herbicidins are new antibiotics having an adenine nucleoside moiety in their structures.
TL;DR: Metabolism of D-glucose by Bacteroides ruminicola subsp.
Abstract: Metabolism of D-glucose by Bacteroides ruminicola subsp. brevis, strain B14, has been examined. Growth yield studies gave molar growth yields, corrected for storage polysaccharide, of approximately 66 g (dry weight)/mol of glucose fermented. The storage polysaccharide amounted to about 14% of the total dry weight, or 55% of the total cellular carbohydrate, at full growth. After correcting glucose utilization for incorporation into cellular carbohydrate, measurement of product formation showed that 1.1 succinate, 0.8 acetate, and 0.35 formate are produced and 0.5 CO2 net is taken up during the fermentation of 1 glucose under the conditions used. The implication of these results with respect to adenosine 5'-triphosphate (ATP) molar growth yield calculations is discussed. If substrate-level phosphorylation reactions alone are responsible for ATP generation, then the ATP molar growth yield must be about 23 g (dry weight)/mol of ATP. Alternatively, if anaerobic electron transfer-linked phosphorylation also occurs, the ATP molar growth yield will be lower.
TL;DR: In this paper, a qualitative and quantitative study of several components formed over a two-year period was undertaken to gain insight into the many microbiological transformations occurring during the spontaneous fermentation of Belgian lambic and gueuze.
Abstract: Lambic is a type of Belgian beer obtained by spontaneous fermentation of wort. The fermentation in casks takes almost two years, and after that period the beer may be re-fermented in bottles and is then called gueuze. To gain insight into the many microbiological transformations occurring during this process, a qualitative and quantitative study of several components formed over a two-year period was undertaken. It was found that lambic and gueuze are characterized by high contents of ethyl acetate, ethyl lactate, lactic acid and acetic acid. Two phases of fermentation may be distinguished: a primary phase lasting for about three months during which almost all the ethanol and higher alcohols are formed and a very long secondary phase during which lactic acid is formed first, followed by ethyl lactate. Some lower fatty acids, including all the acetic acid, are made at the very beginning of the first phase. An important part of the ethyl acetate is made during the first phase but the amounts increase slowly to high levels during the second phase. Unusually low amounts of isoamyl acetate are detected. Several components are above the reported threshold levels of taste and are thus probably involved in the genesis of the typical aroma of lambic and gueuze. These results will allow a further study of the relations between the components found and the microbial populations involved in the spontaneous fermentation inherent in the brewing of lambic and gueuze.
TL;DR: Derivatives of pleuromutilin, formed during the fermentation of Pleurom utilin, were isolated and their structure determined and the possible biosynthetic pathways are shown.
Abstract: Derivatives of pleuromutilin, formed during the fermentation of pleuromutilin, were isolated and their structure determined. 14-Acetyl-mutilin and mutilin as well as different unsaturated fatty acid esters of pleuromutilin were identified. The proportion of each derivative formed depends to a considerable degree on the conditions of the fermentation process. The possible biosynthetic pathways are shown.
TL;DR: A new technique is described for determining the fermentation reactions of non-sporing anaerobes using horse blood agar plates, which is simple, sensitive and yields reproducible fermentation patterns.
Abstract: 1A new technique is described for determining the fermentation reactions of non-sporing anaerobes.
2The fermentation reactions are carried out on horse blood agar plates to which fermentable substrates are added.
3The technique is simple, sensitive and yields reproducible fermentation patterns.
TL;DR: In this paper, a 668% betacyanine content was achieved in the final dry product, the fermentable carbohydrate, nitrates and 80% of the Kjeldahl nitrogen were assimilated by Gmdida utilis after 6.5 hr of fermentation by maintaining the pH at 5.0 with NaOH and HCl solutions.
Abstract: Recent limitations on the use of artificial red food colorants has prompted extensive research into finding suitable natural red pigments as color additives. Investigations have shown that water-based concentrates or powders of red beet root (Beta vulgaris) are applicable colorants in some food systems. However, presently available commercial beet preparations have relatively low pigment concentration; therefore, large quantities are required to obtain the desired color strength. Fermentation of ultrafiltered red beet juice by Candidu utilis under partial anaerobic conditions was shown to substantially reduce solids, resulting in a five- to sevenfold increase in betacyanine content on a dry basis. A 668% betacyanine content was achieved in the final dry product, The fermentable carbohydrate, nitrates and 80% of the Kjeldahl nitrogen were assimilated by Gmdida utilis after 6.5 hr of fermentation by maintaining the pH at 5.0 with NaOH and HCl solutions. After drying, the product lacked the characteristic beet flavor and aroma and was readily water soluble. This dry betacyanine concentrate may have application as a red food colorant.
TL;DR: Several samples of buttermilk also exhibited the near absence of glucose, and lactose content of yogurt mix was higher than expected, and galactose content remained a trace throughout fermentation.
Patent•
05 Mar 1976
TL;DR: In this article, the authors proposed a method to solve the problem of poorly soluble gases in fermentation liquids by dissolving the gas in an aqueous medium, usually water, under superatmospheric conditions and injecting the gas solution into the fermentation liquid in controlled quantities.
Abstract: The bubbling of poorly soluble gases into fermentation liquids either for the replenishment of dissolved oxygen or for removal of excess super-saturated CO 2 can lead to severe foaming problems, particularly in deep fermentation vessels. The present invention overcomes this problem by dissolving the gas in an aqueous medium, usually water, under superatmospheric conditions and injecting the gas solution into the fermentation liquid in controlled quantities under conditions such that the gas is either retained in solution in the fermentation liquid or, at most, the gas is released from solution in the form of microbubbles of much smaller size than can be obtained by passing gas through a porous diffuser. Microbubbles may be released from the gas solution by injecting the pressurized gas solution into the fermentation liquid under conditions of high shear rate.
TL;DR: The results suggest that zinc plays a role in the regulation of growth and citric acid accumulation and Iron, manganese, calcium at concentrations as high as 5-10 muM had no influence on either growth or citrate accumulation.
Abstract: The citric acid fermentation by Aspergillus niger is divided into two consecutive phases, a growth phase when the cells proliferate but do not accumulate citrate, followed by an accumulating phase when they produce citrate but do not proliferate, or else do so at a much reduced rate. When studied in a low sucrose (0.4-0.8%) mpinimal salts medium the growth-accumulation alternative was controlled by the concentration of zinc: high zinc (about 1-2 muM) maintained growth phase, while at low zinc (below 1 muM) growth became limited by zinc deficiency and the cultures passed into accumulating phase. Addition of zinc to accumulating cultures resulted in their reversion to growth phase. Iron, manganese, calcium at concentrations as high as 5-10 muM had no influence on either growth or citrate accumulation. These results suggest that zinc plays a role in the regulation of growth and citric acid accumulation.