Showing papers on "Fermentation published in 1972"

Aspergilli as ochratoxin producers.

Abstract: To determine whether ochratoxin is produced by species of Aspergillus other than Asp. ochraceus, 44 strains representative of the 9 spp. composing the Asp. ochraceus group were grown on both pearled wheat and cracked corn in duplicate shaken flasks at 28°C for 5 days. Rice was a poor substrate for ochratoxin production. Moulded substrates were extracted with acetonitrile-water; partially purified extracts were assayed for ochratoxins by TLC. All positive samples were confirmed by solubility in sodium bicarbonate and preparation of methyl esters. Ochratoxins A and B were found in some strains of Asp. sulphureus, Asp. sclerotiorum, Asp. alliaceus, Asp. melleus, Asp. ochraceus, Asp. ostianus, and Asp. petrakii. No ochratoxin was produced by the one strain of Asp. elegans or any of 6 strains of Asp. auricomus. 5 of 9 strains of Asp. sclerotiorum and 5 of 11 strains of Asp. ochraceus were negative. All 7 strains of Asp. alliaceus were positive, but one was at a very low level. Generally, yields of ochratoxin were higher in wheat than in corn. Occasionally, as much ochratoxin B was produced as A. Highest yields of ochratoxins A and B were obtained from respective strains of Asp. ochraceus NRRL 3174 and NRRL 3519. Some strains of most species of the Asp. ochraceus group produce this mycotoxin as a secondary metabolite.

Carboxylic acid patterns in Ogi fermentation

Abstract: The fermentation rate and carboxylic acids of Ogi, a Nigerian fermented cereal porridge, have been investigated. As a measure of fermentation rate, the acidity of steeped grain was evaluated by extracting the acids with a suitable solvent and titrating against a standard alkali. Since the method is time consuming, the titratable acidity of the aqueous centrifugate may be preferred in routine quality control operations. The carboxylic acids of Ogi fermentation were analysed using paper, gas-liquid and thin-layer chromatography. Eleven acids were identified, lactic, acetic and butyric acids being the most important.

Fermentation of various glycolytic intermediates and other compounds by rumen micro-organisms, with particular reference to methane production.

Abstract: Experiments with a small-scale artificial rumen have shown that of forty-two compounds tested the majority were fermented, as judged by the production of volatile fatty acids, but methane production was associated only with the fermentation of formate, certain hydroxy-acids, pyruvic acid, primary alcohols (methanol, ethanol, propanol and butanol), glycerol and methyl compounds. With primary alcohols there was a stoichiometric relationship between methane production and the oxidation of the alcohols to the corresponding acids.The fermentation of rhamnose and 1,2-propanediol was studied in detail. With both compounds there was a temporary accumulation of lactic acid and a continuous net production of propionic acid. The initial rate of acetate production was rapid with rhamnose but decreased subsequently, whereas propionate continued to increase. With propanediol the net rate of production of acetate was slow at first and then increased. There was no increase in the production of butyric acid with either rhamnose or propanediol, and the endogenous methane production was inhibited by 20–40%. There was evidence for the formation of an unidentified compound during fermentation of rhamnose and propanediol.

Influence of oxygen on growth, cytochrome synthesis and fermentation pattern in propionic acid bacteria.

Abstract: Summary: The influence of oxygen on growth and cytochrome synthesis was investigated in four species of Propionibacterium After anaerobic growth all species contained cytochrome b, cytochrome a or a 1, cytochrome a 2 and a carbon monoxide-binding pigment Cytochrome b functions in an electron transport system from lactate to fumarate since the lactate-fumarate dismutation reaction, unlike lactate oxidation via methylene blue, was strongly inhibited by 2-n-heptyl-4-hydroxyquinoline-N-oxide (HOQNO) No species grew on agar plates under aerobic conditions but all grew in aerated media, though at different rates and with diminished synthesis of all cytochromes In Propionibacterium freudenreichii and P shermanii, which grew slower under aerobic conditions than P rubrum and P pentosaceum, cytochrome synthesis was more repressed by oxygen Large amounts of pyruvate accumulated under aerobic conditions whereas acetate, propionate and succinate were not formed The bacteria are therefore dependent on oxidative phosphorylation for energy under aerobic conditions For P freudenreichii an Y 0 value (g dry wt bacteria/g-atom oxygen taken up) of 15 was measured, suggesting a P/O value of 1 to 2 Absence of cytochrome synthesis resulting in the loss of oxidative phosphorylation may explain the absence of aerobic growth on agar plates

Fermentation of Fructose and Synthesis of Acetate from Carbon Dioxide by Clostridium formicoaceticum

Abstract: Clostridium formicoaceticum ferments fructose labeled with 14C in carbon 1, 4, 5, or 6 via the Embden Meyerhof pathway. In fermentations of fructose in the presence of 14CO2, acetate is formed labeled equally in both carbons. Extracts convert the methyl groups of 5-methyltetrahydrofolate and methyl-B12 to the methyl group of acetate in the presence of pyruvate. Formate dehydrogenase, 10-formyltetrahydrofolate synthetase, 5,10-methenyltetrahydrofolate cyclohydrolase, 5,10-methylenetetrahydrofolate dehydrogenase, and 5,10-methylenetetrahydrofolate reductase are present in extracts of C. formicoaceticum. These enzymes are needed for the conversion of CO2 to 5-methyltetrahydrofolate. It is proposed that acetate is totally synthesized from CO2 via the reactions catalyzed by the enzymes listed above and that 5-methyltetra-hydrofolate and a methylcorrinoid are intermediates in this synthesis.

Characteristics of S Organism Isolated from Methanobacillus omelianskii

Abstract: Previous work showed that Methanobacillus omelianskii was a mixed culture of an ethanol-oxidizing organism called S organism and a hydrogen-utilizing methane bacterium, strain MOH. S organism grows poorly on ethanol unless a hydrogen-utilizing methanogenic bacterium is included to utilize the H2 produced during growth. Further studies have shown that, among many substrates tested, only ethanol, n-propanol, n-butanol, isobutanol, n-pentanol, acetaldehyde, oxalacetate, and pyruvate are fermented by S organism, either alone or in combination with Methanobacterium ruminantium. It grew better in pure culture with pyruvate than with alcohols. H2 gas phase inhibited growth on pyruvate as well as on alcohol. When grown alone on pyruvate, S organism produced mainly acetate, ethanol, and CO2, in addition to a small amount of H2. When combined with M. ruminantium, no H2 and very little ethanol were produced and acetate production was increased. When M. ruminantium was present, electrons from pyruvate oxidation by S organism were channeled almost entirely to H2 and hence to methane formation rather than ethanol. Also, S organism utilized more pyruvate when grown with M. ruminantium. Attempts to obtain better growth of S organism on ethanol by addition of many possible electron acceptors were unsuccessful. It grew best between 32 and 45 C, had a per cent guanine plus cytosine content of deoxyribonucleic acid bases of 47.27 ± 0.1, contained no cytochrome, and could be grown on a defined medium with pyruvate as the energy and carbon source and with (NH4)2SO4 as the main nitrogen source. These and other results suggest that S organism belongs in a new genus, but assignment of a definite taxonomic status should await isolation and characterization of more strains.

Kinetic studies of the lactic acid fermentation in batch and continuous cultures

Abstract: Summary The fermentation kinetics of the homofermentative organism Lactobacillus delbrueckii in a glucose-yeast extract medium is studied in both batch and continuous culture under conditions of controlled pH. From a graphical analysis of the batch data, a mathematical model of the process is derived which relates bacterial growth, glucose utilization, and lactic acid formation. The parameters in the model represent the activity of the organism and are a function of pH, having a maximum value at about 5.90. In a continuous stirred tank fermentor (CSTF), the effect of pH, feed concentration, and residence time is observed. The feed medium is a constant ratio of two parts glucose to one part yeast extract plus added mineral salts. An approximate prediction of the steady-state behavior of the CSTF can be made using a method based on the kinetic model derived for the batch case. In making step changes from one steady state to another, the transient response is observed. Using the kinetic model to simulate the transient period, the calculated behavior qualitatively predicts the observed response.

Control of clostridium botulinum and staphylococcus aureus in semi-preserved meat products

Abstract: Clostridium botulinum and Staphylococcus aureus are naturally occurring contaminants in semi-preserved meat products. They can be inhibited by (a) storage below 3 C, (b) 10% sodium chloride (brine concentration), (c) pH values below 4.5, or (d) proper combinations of these factors. However, most meat products do not have the pH values and brine concentrations required to completely inhibit C. botulinum and S. aureus and there is always a risk of temperature abuse. Improved safety can be achieved by adding 1% or more glucose to the product. The glucose will, in the event of temperature abuse, generally be fermented to lactic acid by the indigenous microflora in the product. As a result, the pH value drops to a level at which the brine concentration is sufficient to inhibit C. botulinum and S. aureus. A better approach to safety is to add, together with glucose, a radiation-killed preparation of lactic acid bacteria, e.g., Pediococcus cerevisiae. Such preparations cause a rapid decline in pH only when the p...

Fate of metabolic hydrogen in the rumen.

Abstract: Introduction T h e first axiom of ruminology appears to be: ‘The rumen is a strictly anaerobic system’ (Hungate, 1966) but before we accept this we should examine the evidence for and against this assertion. Probably the strongest evidence for anaerobiosis comes from the studies of the reactions in the rumen, from the stoichiometries observed and from the low oxidation-reduction potential obtaining in the rumen, although some discrepancies exist (Seeley, Armstrong & MacRae, I 969 ; Demeyer, Nevel, Henderickx & Martin, 1970). Many important rumen organisms grown in pure culture are sensitive to oxygen, but the isolated microbes, apart from being separated by countless generations from the original inocula, might behave quite differently in their natural habitat. The evidence that the rumen might be a partially aerobic system is not conclusive, but plentiful. It can be easily demonstrated in vitro that the rumen contents can utilize oxygen with an alteration of the fermentation pattern but with no inhibition of the rate of utilization of substrates (Czerkawski & Breckenridge, 1969). The rumen contents are surrounded by tissues rich in capillaries containing blood with high-oxygen tension compared with the oxygen tension in the rumen which is never more and rarely less than 1% (see review, Czerkawski, 1969). Facultatively anaerobic micro-organisms exist in the rumen and there is evidence of some processes in the rumen that are more common under aerobic conditions, such as oxidation of n-alcohols (Czerkawski & Breckenridge, 1972) or desaturation of long-chain acids (Patton, McCarthy & Griel, 1968 ; Sklan, Volcani & Budowski, 1971). The metabolic hydrogen and possibly oxygen are of vital importance in the energy exchanges in the rumen, and any attempt to manipulate this balanced ecosystem to increase the efficiency of feed conversion, must take the fate of hydrogen and the possible participation of oxygen into consideration.

Characterization and Energetics of Leuconostoc Oenos ml 34

Abstract: Characteristics of the malo-lactic bacterium Leuconostoc oenos ML 34 are reported indicating that this organism, previously designated L. citrovorum ML 34, should be placed in the new species L. oenos Garvie 1967. Of 26 compounds tested, energy sources for the organism were D-glucose, D-fructose, D-ribose, trehalose, and cellobiose. L-malic and citric acids, not energy sources themselves, provided a slight increase in cell yield in the presence of limited carbohydrate. Production of one of the end products, D-lactic acid, greatly exceeded that expected on the basis of the fermentation of glucose and L-malic acid substrates. It was concluded not only that sugar utilization is required for malo-lactic fermentation, but that malo-lactic fermentation also has a profound influence on the metabolism of the organism and implies a stimulation in utilization of carbon sources. Also discussed are the nomenclature and taxonomy of the wine leuconostocs.

The Ecology and Classification of Strains of Lactobacillus collinoides nov. spec.: A Bacterium Commonly Found in Fermenting Apple Juice

Abstract: Summary: Most heterofermentative lactic rods occurring throughout the cider industry are quite similar and form a fairly coherent group. The constituent bacteria are sufficiently different from other heterofermentative lactobacilli to be considered a new species. They have, therefore, been named Lactobacillus collinoides nov. spec. These occur most frequently in factories where sulphur dioxide, the only permitted preservative, is either used in small quantities or not at all.

The fermentation of L-sorbose by Gluconobacter melanogenus. I. General characteristics of the fermentation.

Abstract: Growing cultures, washed cells, and cell-free preparations of Gluconobacter melanogecnus IFO 3293 converted L-sorbose to 2-keto-L-gulonic acid, to D-sorbitol (which was metabolized further) and to 5-keto-D-fructose.

Influence of Yeast Strain and Malo-Lactic Fermentation on Composition and Quality of Table Wines

Abstract: The micro-organisms which can grow in grape juice and wine are limited to yeasts, lactic and acetic acid bacteria, and in rare cases, possibly sporing bacilli. Pure yeast cultures are becoming widely used in technologically advanced winemaking countries. The yeast must conduct the alcoholic fermentation or at least dominate the naturally occurring microflora. The benefits found from use of selected pure yeasts are rapid onset of fermentation, even and complete fermentation leaving no residual sugar, and elimination of undesirable products of fermentation such as hydrogen sulfide. Yeasts may also be selected for their ability to decompose L-malic acid partially or completely. Mixed yeast cultures may be desirable, but their use in practical winemaking presents problems. Sherry-flor and other oxidative film yeasts bring about changes in the composition and quality of wines. More chemical studies of products formed by such yeasts are desirable. Yeast clouding of bottled wine is a recurring problem, particularly with sweet wines of low alcoholic strength. Malo-lactic fermentation is the bacterial decomposition of L-malic acid to lactic acid and carbon dioxide. It is brought about by lactic acid bacteria and is widespread in red table wines in most winegrowing areas. It renders the wine stable to subsequent breakdown of malic acid, and may improve the flavor of the wine. Diacetyl and other secondary products may be formed as an indirect result of malo-lactic fermentation. Dry red wines with pH values above about 3.8 do not benefit from malo-lactic fermentation. If sugar is present in such wines, bacterial growth may cause spoilage. Factors which encourage malo-lactic fermentation are low alcohol, high pH, low sulfur dioxide, late racking, and warm temperature. The opposite factors discourage malo-lactic fermentation. Considerable progress has been made toward induction of malo-lactic fermentation by addition of selected bacteria, but further work is needed.

Process of making the feed stuff containing bagasse, protein, and yeast

Abstract: Disclosed is a process of making a feed stuff for cattles, pigs, or poultry by subjecting a mixture of bagasse, Candida utilis or a variety of yeast fungus, var major, and Trichoderma viride to a fermentation treatment, mixing a fermentation product with the crushed and dried top portion of sugar canes, having added thereto cereals, and rolling and drying a resultant mixture into a desired shape. Also disclosed is the invention of the apparatus suitable for conducting the above process.

Heterofermentative Carbohydrate Metabolism of Lactose-Impaired Mutants of Streptococcus lactis

Abstract: Two mutants of Streptococcus lactis ATCC 11454 have been isolated which possess an impaired lactose-fermenting capacity; galactose utilization is also affected, but to a lesser extent Although the Embden-Meyerhof-Parnas pathway is the major, if not the sole, pathway of carbohydrate metabolism in the three strains, the fermentation end products of the mutants are dramatically different from the typical homolactic pattern of the wild type Under conditions of low oxygen tension and growth-limiting lactose concentrations, mutant strain T-1 produces largely formic acid, acetic acid (2:1), and ethanol rather than lactic acid Aerated cultures produce acetic acid, CO(2) (1:1), acetyl-methylcarbinol, and diacetyl When the mutants use galactose as an energy source, lactic acid is the major end product, but significant heterofermentative activity is observed The aberrations responsible for the mutant phenotypes reside in the proteins which catalyze the transport and hydrolysis of galactosides It is hypothesized that the impaired transport system of the mutants reduces the intracellular pool of glycolytic intermediates below that of the wild type Since fructose-1, 6-diphosphate is an activator of lactic dehydrogenase in S lactis, lactic acid production is reduced, and pathways leading to the formation of other products are expressed

End-products, fermentation balances and molar growth yields of homofermentative lactobacilli.

Abstract: SUMMARY: Y(glucose) values for Lactobacillus plantarum, L delbrueckii, L casei, L lactis and L bulgaricus, grown as batch cultures in defined medium, and L casei, grown in complex medium, were 200 to 333Y(galactose) values for L plantarum were 257 to 325 Each species produced acetate in addition to lactate, and Y(ATP) values, corrected for the energy produced simultaneously with the formation of acetate, were 100 to 109, close to 105, proposed as a standard value by Bauchop & Elsden (1960) Neither formate nor ethanol was produced in more than trace quantities Y(glucose) values determined for L lactis and L bulgaricus at 40 °C were less than 50% of those determined at 37 °C Production of lactate and acetate accounted for all of the glucose utilized at both temperatures, indicating that the production of ATP by L lactis or L bulgaricus at 40 °C was not coupled closely to the utilization of ATP in the synthesis of bacterial mass

Wort composition and beer flavour. ii. the influence of different carbohydrates on the formation of some flavour components during fermentation

Abstract: Wort, to which was added various amounts of solutions of glucose, fructose, sucrose or maltose, was fermented, and in the resulting beers the concentrations of the following flavour components were determined by gas chromatography: ethyl acetate, isobutyl acetate, iso-amyl acetate, 2-phenyl ethyl acetate, ethyl caproate, ethyl caprylate, n-propanol, isobutanol, amyl alcohols, 2-phenyl ethanol, caprylic acid and capric acid. The concentrations of these compounds were affected in different ways by the various amounts of sugar added, and some differences were observed etween the different carbohydrates.

Glucose Degradation, Molar Growth Yields, and Evidence for Oxidative Phosphorylation in Streptococcus agalactiae

Abstract: In a complex medium with the energy source as the limiting nutrient factor and under anaerobic growth conditions, Streptococcus agalactiae fermented 75% of the glucose to lactic acid and the remainder to acetic and formic acids and ethanol. By using the adenosine triphosphate (ATP) yield constant of 10.5, the molar growth yield suggested 2 moles of ATP per mole of glucose from substrate level phosphorylation. Under similar growth conditions, pyruvate was fermented 25% to lactic acid, and the remainder was fermented to acetic and formic acids. The molar growth yield suggested 0.75 mole of ATP per mole of pyruvate from substrate level phosphorylation. Under aerobic growth conditions about 1 mole of oxygen was consumed per mole of glucose; about one-third of the glucose was converted to lactic acid and the remainder to acetic acid, acetoin, and carbon dioxide. Molar growth yields indicated 5 moles of ATP per mole of glucose. Estimates based on products of glucose degradation suggested that about one-half of the ATP was derived from substrate level phosphorylation and one-half from oxidative phosphorylation. Addition of 0.5 m 2,4-dinitrophenol reduced the growth yield to that occurring in the absence of oxygen. Aerobic pyruvate degradation resulted in 30% of the substrate becoming reduced to lactic acid and the remainder being converted to acetic acid and carbon dioxide, with small amounts of formic acid and acetoin. The molar growth yields and products found suggested that 0.70 mole of ATP per mole of pyruvate resulted from substrate level phosphorylation and 0.4 mole per mole of pyruvate resulted from oxidative phosphorylation.

Use of tartaric acid isomers and citric acid in the biotyping of Salmonella typhimurium

Abstract: The colour-change and lead acetate tests for fermentation of d-, l- and m-tartaric acids and citric acid used in the Kristensen scheme for biotyping Salmonella typhimurium were found to be unreliable because, whatever the conditions of culture, they gave different results in replicate tests of the same strains. Many genotypically non-fermenting strains gave inconsistent reactions due to the emergence of fermenting mutant bacilli in some of their test cultures. No reliable test was found for the fermentation of citric acid. A `turbidity' test was found to give consistent and reliable results with the three tartaric acid isomers. It demonstrated fermentation by the significantly greater amount of growth obtained in a 24 hr. culture in Oxoid peptone water with added isomer than in a control culture without isomer. Lewis & Stocker's (1971) plateinhibition test for fermentation of m-tartrate, which identifies m-tartrate-negative strains because m-tartrate inhibits their growth on citrate- or glycerol-containing minimal medium, was found to be as reliable as, and easier to read than, the turbidity test. Use of the turbidity test for d- and l-tartrates and the plate-inhibition test for m-tartrate in biotyping 1435 strains of S. typhimurium showed that many strains had previously been mistyped by the lead acetate test and distinguished 16 new biotypes in addition to the 22 biotypes already recognized.

Genes for the fermentation of maltose and -methylglucoside in Saccharomyces carlsbergensis.

Abstract: 1. Saccharomyces carlsbergensis N.C.Y.C.74 was shown to be diploid and heterothallic. On acetate medium four spored asci were produced with a spore viability of no more than 2%. However diploid hybrids from the viable spores yielded asci with a spore viability of 75%, thus making tetrad analysis and consequently a genetical study of sugar fermentation in this strain feasible. 2. Auxotrophic mutants in a haploid derivative of this strain were obtained, some of which could be classified as ade1, ade2, ade4, ade5, ade6, ade7, ura2, ura3, lys1, trp2, trp5, his4 and his5. 3. 150 Random spores all fermented glucose, sucrose, mannose, galactose, melibiose, raffinose, and maltose, but only 28% fermented α-methylglucoside. The same fermentation pattern was found in petites of these 150 spores, except that 40% grew poorly on galactose; this gal phenotype could not be ascribed to a single gene. 4. In crosses with mal strains the maltose fermenting ability of the spores from S. carlsbergensis appeared to be dependent upon 1 single gene, which could be identified as MAL6, one of the 7 known polymeric genes for maltose fermentation in Saccharomyces. 5. Our strain was found to be heterozygous for 2 unlinked MGL genes, in this paper indicated as MGLa, and MGLb, both indispensable for the fermentation of α-methylglucoside. 6. After mutagenesis of a haploid strain with genotype MGLaMGLb, one mgl mutant was found, which complemented a strain with genotype mglamglb. This third indispensable MGL gene, preliminarily called MGLc, is homozygously present in our strain and is not linked to either MGLa or MGLb.

Some effects of wort composition on the rate and extent of fermentation by brewing yeasts

Abstract: The time required to ferment worts of varied composition to a given extent is dependent upon the extent of exponential growth in the early stages of fermentation; in the worts studied this is determined by the concentration of assimilable nitrogen. When the concentration of all the non-carbohydrate nutrients in malt wort is halved by dilution with carbohydrate, the addition of appropriate quantities of serine or arginine restores the rate of fermentation to that of the malt wort. Minor nutrients, other than amino acids specifically required by the yeasts used, are thus present in at least two-fold excess in the malt wort. The yeast produced during exponential growth in malt wort (sp.gr. 1·040) is able to ferment rapidly much greater quantities of fermentable carbohydrate than are present in that wort. The majority of the strains of yeast examined ferment equally well when either glucose or maltose is added to malt wort and do so whether the sugar is added prior to fermentation or towards the end; however, one strain fails to ferment satisfactorily if a substantial quantity of glucose is added to wort prior to fermentation, because of the subsequent failure of the yeast to adapt to ferment maltose. It is suggested that most brewing strains do not require to adapt to maltose utilization during the fermentation of wort.

Effect of fermentation temperature on changes in meat properties and flavor of summer sausage

Abstract: Changes in several parameters during summer sausage fermentation by Pediococcus cerevisiae at 22, 30, and 37 C were followed over a 72 hr period. A decrease in meat pH from 5.9 to 4.6 was significantly correlated with the increase of lactic acid. Significantly less acid was produced at 22 C than at 30 and 37 C. The meat water-holding capacity, as determined by extract release volumes, was significantly affected by time and temperature of fermentation. Lactic acid production was correlated with growth of the added starter culture but maximal amounts of lactic acid were not produced until approximately 24 hr after maximal cell populations were reached. Panel analysis of summer sausage fermented at 22 and 37 C showed that fermentation temperature within this range did not significantly affect product flavor. The importance of this latter finding to meat processors is discussed.