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PubMed1999

Identification and characterization of Enterococcus species isolated from forage crops and their influence on silage fermentation.

Forty-eight strains of lactic acid bacteria were isolated from forage crops, and their identification, characterization and influence on silage fermentation were studied. All isolates were Gram-positive, short-chain-forming, catalase-negative, and facultatively anaerobic cocci that did not produce gas from glucose, only formed L-lactic acid, and were able to grow at pH 9.6%, in 6.5% NaCl, or with 40% bile, but not below pH 4.5. These isolates were commonly isolated from forage crops, and they were divided into four groups (A, B, C, and D) according to sugar fermentation characteristics. Selected strains of FA 5, FA 27, FA 45, and FA 57 were identified as Enterococcus hirae, E. faecalis, E. casseliflavus, and E. mundtii, respectively, on the basis of DNA-DNA homology, Strains FA 5, FA 27, FA 45, and FA 57 and two strains from commercial inoculants, LC 10 (Lactobacillus casei) and LP 15 (L. plantarum), were used as additives to alfalfa and guinea grass silages. Alphalfa and guinea grass silages inoculated with LC 10, LP 15, FA 5 + LC 10, and FA 5 + LP 15-treatments in alfalfa and guinea grass silages had significantly lower pH values, contents of butyric acid and ammonia nitrogen, gas production, and dry matter losses compared with the control silage after 60 d of fermentation. However, the E. hirae FA 5, E. faecalis FA 27, E. casseliflavus FA 45, and E. mundtii FA 57-inoculated silages gave similar values to the control in both types of silage. The FA 27 + LC 10 and FA 27 + LP 15-inoculated silages did not differ in fermentation quality from LC 10 and LP 15-inoculated silages alone. The results confirmed that Enterococcus species were not able to improve silage quality.

Bacteria, Anaerobic↗
PubMed2004

The effect of Lactobacillus casei strain Shirota on the cecal fermentation pattern depends on the individual cecal microflora in pigs.

Probiotic bacteria improve fermentation in the large intestine through interaction with indigenous bacteria. The microflora in the large intestine differ from one individual to another. The objective of this study was to determine whether the different cecal microflora induce different probiotic effects on cecal fermentation in three pigs (pig A, B and C). Pigs were administered fermented milk prepared with the Lactobacillus casei strain Shirota (LCS) as a probiotic for 2 wk. The average number of LCS was higher than 5.0 (log cfu/g cecal digesta) in all pigs. The hierarchical clustering of the temperature-gradient gel electrophoresis (TGGE) profile of cecal bacteria showed that the cecal microflora was slightly altered by the LCS dose in all pigs. However, the molar ratios of cecal butyrate in pigs A and C were significantly increased by LCS. Inversely, the molar ratio of propionate in pigs A and C was significantly decreased by LCS. However, the molar ratio of individual short-chain fatty acid in pig B was not significantly affected by LCS. The hierarchical clustering of the TGGE profiles indicated that the cecal microflora of pig A resembled that of pig C and that of pig B was dissimilar to those of pigs A and C. These results indicated that the effect of LCS on fermentation in the large intestine was possibly dependent on the composition of indigenous microflora.

Animals↗
PubMed1995

Fermentation of radiolabeled carbohydrates by a reconstructed continuous-flow culture effective against Salmonella in broiler chicks.

An 81-d-old continuous-flow (CF) culture of broiler cecal bacteria was maintained in a lactose-based broth. The culture had been previously proven effective against Salmonella colonization in young chicks, especially when the chicks were provided dietary lactose. Portions of the CF culture were batch-cultured in glucose- and lactose-based broths containing 14C-labeled lactose, glucose, galactose, or lactic acid to determine the effect of media carbohydrate on fermentation products. Acetic and propionic acids were the major 14C-labeled fermentation products. 14C-Carbohydrates were fermented to lactic acid and then to acetic and propionic acids. Distribution of radiolabeled fermentation products was effected by the broth carbohydrate and the time postinoculation.

Acetates↗
PubMed2000

Stimulation of starter culture for further reduction of foodborne pathogens during salami fermentation.

This study was conducted to determine if stimulated meat starter culture (MSC; Pediococcus acidilactici) would further control Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus during salami fermentation. Manganese ion (0.005% of MnSO4) was used as a stimulator for the growth and acid production of MSC. After 24-h salami fermentation, nonstimulated MSC and stimulated MSC reduced E. coli O157:H7 levels by 1.3 and 2.3 log10 units, respectively. Nonstimulated MSC reduced L. monocytogenes levels by 1.2 log10 units, whereas the stimulated MSC achieved a 2.2-log10 reduction after 24-h fermentation. In the case of S. aureus, nonstimulated MSC and stimulated MSC reduced S. aureus levels by 1.3 and 2.3 log10 units after 24-h fermentation, respectively. Stimulated MSC by MnSO4 reduced those foodborne pathogens more effectively compared with nonstimulated MSC (P < 0.05).

Animals↗
PubMed2000

Mixed starter cultures to control biogenic amine production in dry fermented sausages.

Several combinations of an amine-negative Lactobacillus sakei strain, along with proteolytic Staphylococcus carnosus or Staphylococcus xylosus strains, were used to study the influence of mixed starter cultures on biogenic amine production during the manufacture of dry fermented sausages. Changes in pH, water content, proteolysis, microbial counts, and biogenic amine contents were simultaneously examined in a spontaneously fermented batch and in three mixed starter-mediated batches. A double-controlled microbial charge initially inoculated as mixed starter culture of L. sakei and Staphylococcus spp. (all amine-negative strains) drastically reduced tyramine, cadaverine, and putrescine accumulation. No production of other aromatic amines such as histamine, phenylethylamine, or tryptamine was observed in any batch. The polyamines, spermine and spermidine, were found in raw materials and their levels decreased slightly in the spontaneously fermented batch. No correlation between proteolysis and biogenic amine production was observed. The use of proper technological conditions favoring starter development and the use of the raw materials with good hygienic quality make it possible to produce fermented sausages nearly free of biogenic amines.

Animals↗
PubMed2004

Biogenic amine formation and "zapatera" spoilage of fermented green olives: effect of storage temperature and debittering process.

The effects of temperature and the debittering process on amine formation and other chemical changes related to "zapatera" spoilage of fermented green table olives during storage, without any chemical correction, were studied. Unwashed olive brines were more concentrated in all analyzed compounds, except NaCl. No changes in formic, acetic, and succinic acids or in ethanol, hydroxytyrosol, or tyrosol were observed in the olive brines during storage. The concentration of putrescine in the brine at the beginning of storage and end of fermentation was about 38 mg/liter, and it did not change during storage. This amine only seems to be produced during the active fermentation phase. The effects of temperature and the type of debittering process and time and its interactions (except the time x temperature x debittering process on pH) had significant effects on the production of cadaverine and tyramine, as well as on changes of pH and lactic and propionic acids. Storage at 15 degrees C produced a complete stabilization of the fermented olives. However, storage of washed olives at 20 and 28 degrees C produced a gradual decrease of lactic acid content, an increase in pH, production of propionic acid, and formation of cadaverine and tyramine, the effect becoming greater as the temperature rose. It appears that formation of cadaverine and tyramine only occurs during storage and might be related to zapatera spoilage. Changes were always significantly lower in unwashed olives, which leads to a practical stabilization of the product.

Biogenic Amines↗
PubMed2005

Interactions of meat-associated bacteriocin-producing Lactobacilli with Listeria innocua under stringent sausage fermentation conditions.

The kinetics of the antilisterial effect of meat-associated lactobacilli on Listeria innocua LMG 13568 were investigated during laboratory batch fermentations. During these fermentations, which were performed in a liquid meat simulation medium, a combination of process factors typical for European-style sausage fermentations was applied, such as a temperature of 20 degrees C and a representative pH and salting profile. Two bacteriocin-producing sausage isolates (Lactobacillus sakei CTC 494 and Lactobacillus curvatus LTH 1174), which have already proven efficacy in sausage trials, and one nonbacteriocinogenic, industrial strain (Lactobacillus sakei I), were evaluated. Staphylococcus carnosus 833 was included in the experiment because of its role in flavor and color development. When grown as a monoculture or upon cocultivation with L. sakei I and S. carnosus 833, L. innocua LMG 13568 developed slightly, despite the stress of low temperature, pH, lactic acid, salt, and nitrite. In contrast, when either of the bacteriocin producers was used, the L. innocua LMG 13568 population was rapidly inactivated with more than 3 log CFU ml(-1) after 2 days of fermentation. A bacteriocin-tolerant L. innocua LMG 13568 subpopulation (4 X 10(-4)) remained after bacteriocin inactivation. Thus, when the initial level of L. innocua LMG 13568 equaled 3 log CFU ml(-1), all cells were inactivated and no bacteriocin-tolerant cells were detected, even after 7 days of incubation. S. carnosus was not inactivated by the Lactobacillus bacteriocins and displayed slight growth.

Animals↗
PubMed1978

HPLC as a rapid means of monitoring erythromycin and tetracycline fermentation processes.

Reverse phase high performance liquid chromatography (HPLC) was used as a rapid means of monitoring the erythromycin and the tetracycline fermentation processes. The sample preparation process for tetracycline in the fermentation broth includes simple dilution and filtration through a Millipore filter prior to injection into the HPLC column. Fermentation growth samples showed no interference, and excellent separation for selective determination of tetracycline, 4-epitetracycline, anhydrotetracycline, chlortetracycline, and 4-epianhydrotetracycline was obtained. The relative standard deviation for the HPLC analysis for tetracycline is about one percent and the correlation coefficient between the HPLC and the spectrophotometric assay methods is better than 0.994. The sample preparation procedure for erythromycin determination in fermentation broth requires solvent cleanup and extraction processes. The chromatographic analysis takes approximately 25 minutes, and the HPLC method is capable of separating and quantifying erythromycins A, B, C, and various epimers and degradation compounds. The correlation coefficient between the HPLC and the microbiological assay method is 0.970.

Biological Assay↗
PubMed1998

Fermentation studies of rustmicin production by a Micromonospora sp.

The antifungal antibiotic rustmicin was detected in the fermentation broth of the actinomycete MA 7094 as a specific inhibitor of sphingolipid biosynthesis in Candida albicans and as a potent fungicidal agent against Cryptococcus neoformans. Taxonomic characterization by both classical means and PCR fingerprinting supported the assignment of the producing culture to the genus Micromonospora. Fermentation medium optimization studies showed that the concentration of tomato paste in the medium was critical to increased production of rustmicin by MA 7094. The stimulatory effect of tomato paste in the medium on rustmicin production appeared to be related to the maintenance of pH at or below a value of 6.0. Addition of the antifoam agent P-2000 to the fermentation was found to dramatically reduce the rustmicin titer, while substitution of another antifoam agent, UCON-LB625, resulted in a 100% increase in the amount of rustmicin detected. After fermentation optimization studies and the generation of a non-sporulating mutant of MA 7094, the rustmicin titer was increased from an initial titer of 10mg/liter to 145 mg/liter.

Antifoaming Agents↗
PubMed1998

Catabolite repression mutants of Saccharomyces cerevisiae show altered fermentative metabolism as well as cell cycle behavior in glucose-limited chemostat cultures.

In glucose-limited continuous cultures, a Crabtree positive yeast such as Saccharomyces cerevisiae displays respiratory metabolism at low dilution rates (D) and respiro-fermentative metabolism at high D. We have studied the onset of ethanol production and cell cycle behavior in glucose-limited chemostat cultures of the wild type S. cerevisiae strain CEN.PK122 (WT) and isogenic mutants, snf1 (cat1) and snf4 (cat3) defective in proteins involved in catabolite derepression and the mutant in glucose repression mig1 (cat4). The triggering of fermentative metabolism was dependent upon catabolite repression properties of yeast and was coincident with a significant decrease of G1 length. WT cells of the strain CEN.PK122 displayed respiratory metabolism up to a D of 0.2 h-1 and exhibited longer G1 lengths than the snf1 and snf4 mutants that started fermenting after a D of 0.1 and 0.15 h-1, respectively. The catabolite derepression mutant snf4 showed a significant decrease in the duration of G1 with respect to the WT. An increase of 300% to 400% in the expression of CDC28 (CDC28-lacZ) with a noticeable shortening in G1 to values lower than approximately 150 min, was detected in the transformed wild type CEN.SC13-9B in glucose-limited chemostat cultures. The expression of CDC28-lacZ was analyzed in the wild type and isogenic mutant strains growing at maximal rate on glucose or in the presence of ethanol or glycerol. Two- to three-fold lower expression of the CDC28-lacZ fusion gene was detected in the snf1 or snf4 disruptants with respect to the WT and mig1 strains in the presence of all carbon sources. This effect was further shown to be growth rate-dependent exhibiting apparently, a threshold effect in the expression of the fusion gene with respect to the length of G1, similar to that shown in chemostat cultures. At the onset of fermentation, the control of the glycolytic flux was highly distributed between the uptake, hexokinase, and phosphofructokinase steps. Particularly interesting was the fact that the snf1 mutant exhibited the lowest fluxes of ethanol production, the highest of respiration and correspondingly, the branch to the tricarboxylic acid cycle was significantly rate-controling of glycolysis.

Biotechnology↗
PubMed2000

Fermentative capacity in high-cell-density fed-batch cultures of baker's yeast.

High-cell-density fed-batch processes for bakers' yeast production will involve a low-average-specific growth rate due to the limited oxygen-transfer capacity of industrial bioreactors. The relationship between specific growth rate and fermentative capacity was investigated in aerobic, sucrose-limited fed-batch cultures of an industrial bakers' yeast strain. Using a defined mineral medium, biomass concentrations of 130 g dry weight/L were reproducibly attained. After an initial exponential-feed phase (mu = 0.18 h(-1)), oxygen-transfer limitation necessitated a gradual decrease of the specific growth rate to ca. 0.01 h(-1). Throughout fed-batch cultivation, sugar metabolism was fully respiratory, with a biomass yield of 0.5 g biomass/g sucrose(-1). Fermentative capacity (assayed off-line as ethanol production rate under anaerobic conditions with excess glucose) showed a strong positive correlation with specific growth rate. The fermentative capacity observed at the end of the process (mu = 0.01 h(-1)) was only half that observed during the exponential-feed phase (mu = 0.18 h(-1)). During fed-batch cultivation, activities of glycolytic enzymes, pyruvate decarboxylase and alcohol dehydrogenase in cell extracts did not exhibit marked changes. This suggests that changes of fermentative capacity during fed-batch cultivation were not primarily caused by regulation of the synthesis of glycolytic enzymes.

Alcohol Dehydrogenase↗
PubMed2000

[Studies on fermentation of decane 1,10-dicarboxylic acid(DC12)].

Candida tropicalis strain UH-2-48 can increase the production of decane 1,10-dicarboxylic acid(DC12) yield by 30% (from 81.7 g/L to 108.2 g/L) after regulating the fermentation condition. The purity of the DC12 is above 97%, which can meet the criteria of the succeeding synthesized industrial productions. Emulsifier can not only destroy the structure of the cell membrane in some degree, but also can enhance the permeability of the cell membrane. Furthermore, the structure of the emulsifier itself can also effect its function. Tween 60(0.10%) can enhance the production of DC12 tremendously. Urea, as the nitrogen resource, can affect the activity of cytochrome P450 enzyme. Some biochemistry and biophysics factors, such as penicillin, vitamin B2 and alanine, can increase the yield of DC12 during the process of fermentation. Ferment in 20 m3 fermentator, under the optimal condition, the average yield of DC12 using the strain HP-12 which derived from UH-2-48, is 202.1 g/L.

Candida↗
PubMed2000

[Impact of lactic acid fermentation in the large intestine on acute lactic acidosis in cattle].

Microbial and fermentation changes in the ingesta of the large intestine and their influence on the pathogenesis of acute lactic acidosis were studied in 4 cows fitted with permanent cannulas in the ileum and cecum. Feed mixture containing 65% of maize was infused into the cecum for several days in amounts of 2 and 4 kg per day. The daily amount was divided in 8 equal portions and given with 3 l of warm physiologic saline solution. During the period of ad libitum feeding of hay, the pH values in cecal digesta were 7.4 to 7.6 and the amount of total volatile fatty acids 40-60 mmol/kg with high molar percentage (87-90 mol%) of acetic acid. As to lactic acid only the L(+) lactic isomer was found in a concentration of about 0.4 mmol/kg. Infusion of low amounts of starch induced mild lactic acid fermentation in the cecum associated with a pronounced increase in the concentration of L(+) and D (-) lactic acid to peak levels of 80 +/- 10 mmol/kg and 7 +/- 1 mmol/kg, respectively. Lactic acid fermentation ceased within 2 to 3 days indicating that the gut microflora had adapted to the starch infusion. Slight decreases of blood pH and bicarbonates in blood as well as a moderate increase of netto acid-base excretion in urine indicated mild changes of acid-base balance, but clinically no pathological symptoms were observed. Higher amounts of infused starch caused pronounced lactic acid production in the large intestine which persisted throughout the experiment. Peak L(+) and D(-) lactic acid concentration in cecal digesta reached on the average 137 +/- 16 mmol/kg and 45 +/- 7 mmol/kg respectively. Significant decreases of blood pH values from 7.41 +/- 0.02 to 7.18 +/- 0.08 (P < 0.001), actual bicarbonate from 28.2 +/- 3.2 to 11.0 +/- 2.6 mmol/l (P < 0.001) and base excess from 3.9 +/- 3.6 to -15.2 +/- 3.8 mmol/l (P < 0.001) were observed. D (-) lactic acid concentration in blood increased to 3.2 +/- 0.4 mmol/l, but L(+) lactic acid values remained unchanged under 1 mmol/l. Clear clinical symptoms of indigestion and intoxication characterized by severe inappetence, ruminal stasis and general weakness were also observed. Typical clinical symptoms of disease as well as blood and urine changes in acid-base balance indicated that lactic acid fermentation in the large intestine contributes considerably to the pathogenesis of acute ruminant lactic acidosis.

Acid-Base Equilibrium↗
PubMed2001

Denitrification potential enhancement by addition of anaerobic fermentation products from the organic fraction of municipal solid waste.

The aim of this study is to demonstrate the denitrification potential enhancement determined by the addition of the anaerobic fermentation products from the organic fraction of municipal solid waste in BNR wastewater treatment plants. The denitrification potential rose from 6 to 17 mgNO3-N/l thanks to the good performances showed by the fermentation products in the denitrification step: a typical maximum denitrification rate of about 5 mgN/gVSS d was observed. This value is similar to those obtained by using pure organic substrates. The denitrification capacity increase is determined by a significant increase of S8 and Xs availability in the influent due to the anaerobic fermentation products addition which leads to an influent COD increase equal to 68% of the total load: this value is significantly higher than the one obtained by fermentation of primary and/or waste activated sludge (3-5%).

Bacteria, Anaerobic↗
PubMed2001

Influence of skin maceration and oxygen on anaerobic fermentation of grape musts with high sugar content.

Saccharomyces cerevisiae race cerevisiae was used to ferment grape musts in strictly anaerobic conditions, subjected to a prefermentative treatment of skin maceration and following a short aeration after 48 h of fermentation. Skin maceration caused an increase in the cellular phospholipid content which affected neither viability nor the fermentative capacity of the yeasts. The short aeration had no significant effect on the unsaturation index of the cellular fatty acids, although it did increase the ergosterol/phospholipid ratio. This was reflected by an increase in the growth rate, viability and fermentative capacity of the yeasts. Maceration did not increase the effect of aeration.

Anaerobiosis↗
PubMedDate not supplied

Effect of nisin and monensin on rumen fermentation in the artificial rumen.

The objective of this study was to investigate the effect of nisin and monensin on rumen fermentation of diets containing hay and barley (80:20%) in artificial rumen (Rusitec system). The Rusitec system consisted of four fermentation vessels (V1, V2, V3, V4): V1 was without additives (control), V2 received daily 2 mg of nisin, V3 involved 5 mg of monensin and V4 combination of 2 mg of nisin with 5 mg of monensin. After an adaptation period (7 days), the fermentation parameters were determined for six consecutive days. Compared to control diet, the addition of nisin resulted in an increase (P < 0.05) of hemicellulose degradation, acetate, propionate (mmol.day-1) production and energetic efficiency of VFA (E), decrease of butyrate production. Nisin had no effect on dry matter (DM), organic matter (OM), cellulose and detergent fiber degradation, production of total gas, methane and efficiency of microbial synthesis. The addition of monensin resulted in an decrease of DM, OM (P < 0.05), cellulose, hemicellulose, detergent fiber degradation (P < 0.001), total gas, methane and ammonia nitrogen (NH3-N) production. Monensin also significantly decreased acetate, butyrate, L-lactate (mmol.day-1) production and it increased propionate production (P > 0.001) and efficiency of microbial synthesis. The combined effect of nisin and monensin in V4 was similar to the effect of monensin in V3 compared to control. Then, the effect of additive monensin was dominant over nisin. In conclusion, our results indicate that nisin was less effective than monensin on some fermentation parameters (important for the improvement of the efficiency of utilization of the diet by ruminants) in artificial rumen.

Animal Feed↗
PubMed1998

[Growth of Methylomonas Z201 cells and production of epoxypropane in monophasic and biphasic fermentation systems].

The growth of Methylomonas Z201 cells and production of epoxypropane in mono- and biphasic fermentation systems were studied. In monophasic fermentation systems, the inhibitions of propene and epoxypropane on the growth of Methylomonas Z201 cells were observed and the concentration of epoxypropane reached 1.3 mmol/L. In biphasic fermentation systems, hexadecane acted as the "reservoir" of growth substrate (methane) and reactants (propene, molecular oxygen), the decrease of propene and epoxypropane in aqueous phase reduced the inhibition effect of propene and epoxypropane on the growth of cells, the concentrations of epoxypropane in both water phase and hexadecane phase reached 1.7 mmol/L and 2.6 mmol/L. In both monophasic and biphasic fermentation systems, the operational stability of cells was enhanced compared to that of resting cells.

Alkenes↗