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Effect of pH control on lactic acid fermentation of starch by Lactobacillus manihotivorans LMG 18010T.

Lactic acid fermentation of starch by Lactobacillus manihotivorans LMG 18010T, a new amylolytic L(+) lactic acid producer, was investigated and compared with starch fermentation by Lact. plantarum A6. At non-controlled pH, growth and lactic acid production from starch by Lact. manihotivorans LMG 18010T lasted 25 h. Specific growth and lactic acid production rates continuously decreased from the onset of the fermentation, unlike Lact. plantarum A6 which was able to grow and convert starch product hydrolysis into lactic acid more rapidly and efficiently at a constant rate up to pH 4.5. In spite of complete and rapid starch hydrolysis by Lact. manihotivorans LMG 18010T during the first 6 h, only 45% of starch hydrolysis products were converted to lactic acid. When pH was maintained at 6.0, lactic acid, amylase and final biomass production by Lact. manihotivorans LMG 18010T increased markedly and the fermentation time was reduced by half. Under the same conditions, an increase only in amylase production was observed with Lact. plantarum A6. When grown on glucose or starch at pH 6.0, Lact. manihotivorans LMG 18010T had an identical maximum specific growth rate (0.35 h(-1)), whereas the maximum rate of specific lactic acid production was three times higher with glucose as substrate. Lactobacillus manihotivorans LMG 18010T did not produce amylase when grown on glucose. Based on the differences in the physiology between the two species and other amylolytic lactic acid bacteria, different applications may be expected.

Biomass↗

Yeast communities and genetic polymorphism of Saccharomyces cerevisiae strains associated with artisanal fermentation in Brazil.

Yeast communities and genetic polymorphism of prevalent Saccharomyces cerevisiae strains isolated from the spontaneous fermentation of the sugarcane juice during the production of aguardente in three distilleries in the state of Minas Gerais, Brazil, were studied. S. cerevisiae was the prevalent species during the process of aguardente production, but Schizosaccharomyces pombe was predominant in old fermentations in one distillery. Transient yeast species were found in a variable number, probably due to the daily addition of sugarcane juice, and they were different for each of the three distilleries studied. PFGE and PCR analysis of the predominant strains of S. cerevisiae isolated from the fermented must showed a high degree of genetic polymorphism among the three distilleries. A high molecular variability of S. cerevisae strains was also observed among strains isolated from the same vat at different fermentation ages. Our results showed that there was a succession of geneticly different strains of S. cerevisae during the process of aguardente production.

Alcoholic Beverages↗

Changes in major components of tea fungus metabolites during prolonged fermentation.

Changes in major components and microbes in tea fungus broth (or kombucha; teakwass) prepared from nine different sources during a prolonged fermentation of up to 60 days were investigated. Cell concentrations of both yeasts and acetic acid bacteria in broth were generally higher than those in the cellulosic pellicles. The residual sucrose concentration decreased linearly with time, although the rate fell after the first month. Metabolic fates of glucose and fructose produced as a result of the hydrolysis of sucrose were different. Glucose was not produced in parallel with fructose (0.085 g 100 ml(-1) d(-1)) but was produced with a lower initial rate (0.041 g 100 ml(-1) d(-1)). Both titratable acidity and gluconic acid increased steadily with time for all samples, although gluconic acid was not generated for 6 days until the fermentation had begun. Acetic acid increased slowly to a maximum value of 1.1 g 100 ml(-1) after 30 days; thereafter, it decreased gradually. Gluconic acid contributed to the titratable acidity and thus, the taste of tea fungus broth, during the final stage of fermentation. It is concluded that the desired quality or composition of kombucha can be obtained through the proper control of fermentation time.

Acetic Acid↗

Development of xylose-fermenting yeast Pichia stipitis for ethanol production through adaptation on hardwood hemicellulose acid prehydrolysate.

AIMS: The objective of this study was to develop a mutant from Pichia stipitis NRRL Y-7124, tolerant of high concentrations of acetic acid and other inhibitory components present in acid hydrolysates, to improve ethanol yield and productivity. METHODS AND RESULTS: The mutant was developed through adaptation in acid hydrolysate supplemented with nutrients and minerals at 30 +/- 0.5 degrees C. When it was tested for its ability to ferment acid hydrolysate, it showed shorter fermentation time, better tolerance to acid and could ferment at lower pH. The ethanol yield (Yp/s) and productivity (Qp) were increased 1.6- and 2.1-fold, respectively. CONCLUSION: The development of a mutant and its tolerance to acetic acid present in hydrolysates is described. The selected mutant is capable of fermenting both hexoses and pentoses present in hydrolysate at lower pH in comparison with the parent strain. SIGNIFICANCE AND IMPACT OF THE STUDY: The mutant could play a significant role in reducing environmental pollution by using sugars present in pulp mill effluent and, at the same time, could produce a marketable liquid fuel ethanol.

Acetic Acid↗

Monitoring of Staphylococcus xylosus DSM 20266 added as starter during fermentation and ripening of soppressata molisana, a typical Italian sausage.

AIMS: "Soppressata molisana", a fermented sausage produced in southern Italy, is commonly obtained without starter addition. However, the use of starter cultures is more and more recommended in meat fermentation processes in order to guarantee stable production performance. In this study, the survival of the Staphylococcus xylosus DSM 20266 was evaluated during the ripening of "soppressata molisana" fermented sausage. METHODS AND RESULTS: The fastest method of RAPD-PCR was employed for discrimination of the added strain from those naturally present during the ripening of the "soppressata molisana". The results obtained were confirmed by analysis of the DNA macrorestriction profile by PFGE. The electrophoretic pattern of bacterial total proteins was also studied, but clear differences between the different strains could not be detected. CONCLUSIONS: The RAPD technique was a valid tool for monitoring Staph. xylosus DSM 20266 in "sopressata molisana". SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the possibility of monitoring the presence of Staph. xylosus strains during the ripening of fermented sausages by a reliable and repeatable technique such as RAPD.

Animals↗

Fermentative activity and production of volatile compounds by Saccharomyces grown in synthetic grape juice media deficient in assimilable nitrogen and/or pantothenic acid.

AIMS: To understand the impact of assimilable nitrogen and pantothenic acid on fermentation rate and synthesis of volatile compounds by Saccharomyces under fermentative conditions. METHODS AND RESULTS: A 2 x 3 factorial experimental design was employed with the concentrations of yeast assimilable nitrogen (YAN) (60 and 250 mg l(-1)) and pantothenic acid (10, 50 and 250 microg l(-1)) as variables. In media containing 250 microg l(-1) pantothenic acid, H2S production by two different species of Saccharomyces decreased when YAN was increased from 60 to 250 mg l(-1). Conversely, H2S production was significantly higher when the concentration of assimilable nitrogen was increased if pantothenic acid was deficient (10 or 50 microg l(-1)). Yeast synthesis of other volatile compounds were impacted by both assimilable nitrogen and pantothenic acid. CONCLUSIONS: While growth and fermentative rate of Saccharomyces was more influenced by nitrogen than by pantothenic acid, complicated interactions exist between these nutrients that affect the synthesis of volatile compounds including H2S. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has important implications for the winemaking industry where a better understanding of the nutritional requirements of Saccharomyces is necessary to reduce fermentation problems and to improve final product quality.

Alcohols↗

Degradation of proteins during the fermentation of African locust bean (Parkia biglobosa) by strains of Bacillus subtilis and Bacillus pumilus for production of Soumbala.

AIMS: To examine isolates of Bacillus subtilis and B. pumilus predominant in Soumbala for their ability to degrade African locust bean proteins (ALBP). METHODS AND RESULTS: Agar diffusion test in casein and ALBP agar was used for screening of isolates. The profiles of water-soluble proteins and free amino acids (FAA) during the fermentation of ALBP by the Bacillus isolates were studied by SDS-PAGE and cation exchange chromatography. The profile of soluble proteins changed with the fermentation time and varied depending on the isolate. The quantity of total FAA and essential FAA such as lysine was increased sharply between 24 and 48 h of fermentation and differed among the isolates. Simultaneously, a pH increase was observed. Cysteine, methionine, leucine, isoleucine, tyrosine and phenylalaline appeared during fermentation. CONCLUSION: The Bacillus isolates studied degraded ALBP leading to a profile of soluble proteins and FAA specific for each isolate. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to the selection of Bacillus strains to be used as starter cultures for controlled production of Soumbala.

Amino Acids↗

Typification of Oenococcus oeni strains by multiplex RAPD-PCR and study of population dynamics during malolactic fermentation.

AIMS: The goal of this study was to develop a reproducible method for molecular typing strains of Oenococcus oeni, and also to apply it in the study of population dynamics of these strains during malolactic fermentation of wine. METHODS AND RESULTS: A new method of multiplex randomly amplified polymorphic DNA (RAPD)-PCR has been developed, based on the combination of one random 10-mer and one specific 23-mer oligonucleotide in a single PCR. This method generates unique and discriminant DNA profiles for strains of O. oeni. The strains of this species were also clearly distinguished from other species of lactic acid bacteria. The method was applied to study the dynamics of O. oeni strains during malolactic fermentation, in three vintages in the same cellar. CONCLUSIONS: A fast and reliable method for typing strains of O. oeni has been designed and optimized. It improves the reproducibility and rapidity of conventional RAPD-PCR, and it has been validated monitoring the population dynamics during malolactic fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This method will be a good tool to study the population dynamics of bacteria during malolactic fermentation and to evaluate the performance of new malolactic starter cultures and their dominance over the native microbiota.

Bacterial Typing Techniques↗

Effect of plant oils and aspartate on rumen fermentation in vitro.

The effect of plant oils and aspartate (ASP) on rumen fermentation in vitro. The objective of this study was to determine the effect of plant oils (rapeseed - RO, sunflower - SO; linseed - LO; 10% wt/wt) and 8 mmol sodium aspartate on rumen fermentation of a diet (250 mg) consisting of hay, barley and sugar beet molasses (60 : 30 : 10). Rumen fluid was collected from two Slovak Merino sheep fed the same diet twice daily. Mixed ruminal micro-organisms were incubated in fermentation fluid (40 ml) containing rumen fluid and McDougall's buffer (1 : 4). Incubations were carried out in batch cultures for 72 h at 39 degrees C two times in a 3-week intervals. When compared to the control, all supplemented diets (RO, SO, LO, ASP) significantly increased the pH, the mol% of propionate (LO + 8.7%; SO + 10.12%; RO + 8.65%; ASP + 5.86%) and the acetate : propionate ratio and numerically decreased methane production (SO -32.8%; LO, RO -30.08%; ASP -21.56%). Lactate production was also significantly decreased. Addition of plant oils to aspartate-treated incubations partly inhibited the decrease of n-butyrate, lactate and the increase of pH and in vitro dry matter digestibility (IVDMD) caused by ASP treatment. The effect of combined additives (RO + ASP, SO + ASP, LO + ASP) on methane production SO + ASP (-19.23%) and mol% propionate SO + ASP (+2.66%), LO + ASP (+4.28%) was less effective. All combined additives caused a significant decrease in digestibility of the given feeds. No effect of plant oils and ASP could be observed on the parameters of rumen fermentation (mainly methane and propionate).

Animal Feed↗

Improved polygalacturonase production from Bacillus sp. MG-cp-2 under submerged (SmF) and solid state (SSF) fermentation.

AIMS: To investigate the effect of amino acids, vitamins and surfactants on polygalacturonase production from Bacillus sp. MG-cp-2 under submerged (SmF) and solid state fermentation (SSF). METHODS AND RESULTS: Bacillus sp. MG-cp-2 was isolated from the outer covering of the seeds of Celastrus paniculatus. Out of the various surfactants, amino acids and vitamins, Tween-60, DL-serine and folic acid maximally enhanced polygalacturonase production by 2.7-fold (240.0 U x ml(-1)), 4.0-fold (360.0 U x ml(-1)) and 3.8-fold (342.0 U x ml(-1)) respectively, under submerged fermentation (SmF). In solid state fermentation (SSF), Tween-80, pyridoxine and DL-ornithine monohydrochloride induced highest enzyme production up to 1.73-fold (6956.5 U x g(-1)), 5.3-fold (21224.4 U x g(-1)) and 5.74-fold (23076.9 U x g(-1)), respectively. CONCLUSION: Amino acids and their analogues, vitamins and surfactants effect significantly polygalacturonase production by Bacillus sp. MG-cp-2 when grown under submerged (SmF) and solid state fermentation (SSF) conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides useful information about regulation of polygalacturonase biosynthesis in Bacillus sp. MG-cp-2, which appears to be an interplay of nutritional and physical factors. Alkaline polygalacturonase from Bacillus sp. MG-cp-2 will be extremely useful in the treatment of alkaline pectic waste waters from vegetable and fruit processing industries and in degumming of bast fibres.

Amino Acids↗

Time series analysis of aerobic bacterial flora during Miso fermentation.

AIMS: This article reports a microbiological study of aerobic mesophilic bacteria that are present during the fermentation process of Miso. METHODS AND RESULTS: Aerobic bacteria were enumerated and isolated from Miso during fermentation and divided into nine groups using traditional phenotypic tests. The strains were identified by biochemical analysis and 16S rRNA sequence analysis. They were identified as Bacillus subtilis, B. amyloliquefaciens, Kocuria kristinae, Staphylococcus gallinarum and S. kloosii. All strains were sensitive to the bacteriocins produced by the lactic acid bacteria isolated from Miso. CONCLUSIONS: The dominant species among the undesirable species throughout the fermentation process were B. subtilis and B. amyloliquefaciens. It is suggested that bacteriocin-producing lactic acid bacteria are effective in the growth prevention of aerobic bacteria in Miso. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has provided useful information for controlling of bacterial flora during Miso fermentation.

Bacillus↗

Improved production of teicoplanin using adsorbent resin in fermentations.

AIMS: To use adsorbent resins in fermentations to eliminate toxic effects on growth, reduce feedback repression of production and assist in recovery of teicoplanin. METHODS AND RESULTS: An adsorbent resin was added to the culture broth for the adsorption of teicoplanin. Amberlite XAD-16, Diaion HP-20, charcoal and silica gel were investigated as adsorbent resins. The adsorbed teicoplanin was extracted from the resin by 80% methanol after fermentation. Antibiotic activity was quantified by the disc-agar diffusion assay against Bacillus substilis, and qualitative evaluations were based on HPLC using YMC-Pack ODS-A column. Diaion HP-20 was the most effective adsorbent resin when added at a concentration of 5% (w/v) in the inoculation stage. CONCLUSIONS: Addition of Diaion HP-20 in fermentations eliminated toxic effects on growth and reduced feedback repression of teicoplanin by adsorption. There was a 4.2-fold increase in the quantities of teicoplanin. Addition of adsorbent assisted in the recovery of teicoplanin by reducing the recovery steps. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study provide useful information for the production of teicoplanin, a glycopeptide antibiotic produced by Actinoplanes teicomyceticus. Addition of adsorbent in fermentation increased productivity of teicoplanin by more than five times.

Actinomycetales↗

Attempted induction of reductive acetogenesis into the rumen fermentation in vitro.

Rumen and caecal contents, obtained from slaughterhouse cattle and rumen contents obtained from a fistulated wether were incubated in vitro with ground hay in the presence and absence of, respectively, casein hydrolysate and mucin. Differences in stoichiometry of rumen and caecal fermentations, indicative of reductive acetogenesis in the caecum, were confirmed, except for incubations with free amino acids. Net fermentation end product production was determined after correction for amounts formed in incubations without the substrate. These determined amounts of hay fermentation end products were compared with the amounts calculated from incubations of hay with added casein hydrolysate or mucin, corrected for amounts formed from the latter added substrates incubated alone. With casein hydrolysate, no differences between the determined and calculated amounts were observed, excluding the occurrence of reductive acetogenesis from hay in the presence of free amino acids. With mucin, the calculated amounts indicated an inhibition of methanogenesis, accompanied by increased amounts of proprionate, butyrate and valerate production. This finding was probably related to the greater availability of easily fermented carbohydrates in the presence of mucins. The absence of an increased acetate production in the incubations with added head space hydrogen gas, also indicate the absence of reductive acetogenesis from hay in the presence of mucin. Stoichiometric considerations also indicate that neither free amino acids, nor mucin, induce reductive acetogenesis in short-term in vitro incubations of rumen contents with hay.

Acetates↗

Variation of proteolytic activity in ewe during in vivo digestion of two pea-based diets differing by their fermentability characteristics.

In order to study the effects of a small difference in starch and nitrogen availability on proteolysis, two different diets were supplied to four ewes fitted with rumen fistulae. They differed in the ratio of fermentable nitrogen over fermentable energy. with 144 g of fermentable nitrogen (FN) per kg of fermentable energy (FE) for diet I and 126 g FN x kg(-1) FE for diet II. The diets were constituted of 700 g hay grass, 200 g ground pea and either 100 g ground wheat (diet I) or 100 g corn starch (diet II). After two weeks of an adapting period to the diets, rumen content was sampled after feeding over time. The rate of disappearance of soluble proteins was 2.5 times higher with diet II and ammonia concentrations were significantly lower (from -28 to -43%) with diet II. Total proteolytic activity, by considering all the bacterial compartments, was significantly higher with diet II (+40 EU/mL x h(-1)): changes in the total proteolytic activity in the particulate and the liquid phases of the rumen could explain the difference observed between the two diets. Moreover, with diet II, exopeptidase activities increased more in the liquid phase, especially leucine aminopeptidase and Dipeptidyl peptidase I (DPP-I), and the diversity of endopeptidase activities increased in the particulate phase. These two facts could account for the higher total proteolytic activity in the rumen content with diet II.

Animal Feed↗

Colonic fermentation influences lower esophageal sphincter function in gastroesophageal reflux disease.

BACKGROUND & AIMS: Colonic fermentation of carbohydrates is known to influence gastric and esophageal motility in healthy subjects. This study investigated the effects of colonic fermentation induced by oral administration of fructooligosaccharides (FOS) in patients with gastroesophageal reflux disease (GERD). METHODS: In the cross-over design used in the study, 9 patients with symptomatic GERD were administered a low-residue diet (i.e., 10 g fiber/day) during 2, 7-day periods, receiving either 6.6 g of FOS or placebo 3 times daily after meals. Each period was separated by a wash out of at least 3 weeks. On day 7, esophageal motility and pH were recorded in fasting conditions and after a test meal containing 6.6 g of FOS or placebo. Breath hydrogen concentrations (reflecting colonic fermentation) and plasma concentrations of glucagon-like peptide 1 (GLP-1), peptide YY, and cholecystokinin were monitored. RESULTS: Compared with placebo, FOS led to a significant increase in the number of transient lower esophageal sphincter relaxations (TLESRs) and reflux episodes, esophageal acid exposure, and the symptom score for GERD. The integrated plasma response of GLP-1 was significantly higher after FOS than placebo. CONCLUSIONS: Colonic fermentation of indigestible carbohydrates increases the rate of TLESRs, the number of acid reflux episodes, and the symptoms of GERD. Although different mechanisms are likely to be involved, excess release of GLP-1 may account, at least in part, for these effects.

Administration, Oral↗

Identification of the last unknown genes in the fermentation pathway of lysine.

Although the proteins of the lysine fermentation pathway were biochemically characterized more than thirty years ago, the genes encoding the proteins that catalyze three steps of this pathway are still unknown. We combined gene context, similarity of enzymatic mechanisms, and molecular weight comparisons with known proteins to select candidate genes for these three orphan proteins. We used a wastewater metagenomic collection of sequences to find and characterize the missing genes of the lysine fermentation pathway. After recombinant protein production and purification following cloning in Escherichia coli, we demonstrated that these genes (named kdd, kce, and kal) encode a l-erythro-3,5-diaminohexanoate dehydrogenase, a 3-keto-5-aminohexanoate cleavage enzyme, and a 3-aminobutyryl-CoA ammonia lyase, respectively. Because all of the genes of the pathway are now identified, we used this breakthrough to detect lysine-fermenting bacteria in sequenced genomes. We identified twelve bacteria that possess these genes and thus are expected to ferment lysine, and their gene organization is discussed.

Amino Acid Oxidoreductases↗

Fermentation of dietary fibre components in the rat intestinal tract.

1. The fermentative breakdown of dietary fibre from various sources in the intestinal tract was studied using rat balance experiments and gas-liquid chromatograhic analysis of dietary fibre monomers in feed and faces. 2. On a basal diet with 690 g maize starch/kg but no added fibre, small but detectable amounts of polymeric glucose, rhamnose, arabinose, xylose, galactose, mannose and uronic acids, i.e. sugars occurring in dietary fibre, were excreted in faeces. 3. Dietary fibre in wheat bran was rather resistant to fermentation; 63% was recovered in the faeces. Guar gum, on the other hand, was almost completely fermented, whereas 19 and 25% of the uronic acids in low and high methoxylated pectin respectively, were excreted in faeces. The various constituents of sugar-beet dietary fibre (approximately equal amounts of arabinose-based hemicellulose, pectin and non-starch glucan (cellulose)) showed quite variable availability for micro-organisms in that 6-12% of the arabinose, 17-25% of the uronic acids, and 52-58% of the cellulose were recovered in the faeces. 4. Faecal nitrogen excretion increased on addition of any one of the dietary fibre preparations studied, resulting in decreased true and apparent protein digestibility values. 5. The faecal dry weight increment was most pronounced when feeding bran and could then almost be accounted for by the remaining fibre and by protein. The less-prominent bulking effect of guar gum and pectins, that were much more extensively fermented, could be only partly explained by dietary fibre and protein.

Animals↗

The effect of formaldehyde or glutaraldehyde application to lucerne before ensiling on silage fermentation and silage N digestion in sheep.

The primary growth of lucerne (Medicago sativa) was ensiled after treatment with either formic acid alone (4.1 litres/t; silage F) or with formic acid and either formaldehyde (30.5 g/kg crude protein (nitrogen X 6.25; CP); silage FF), glutaraldehyde (44.2 g/kg CP; silage FG) or a mixture of the two aldehydes at approximately half their individual application rates (silage FFG). Compared with formic acid alone, both formaldehyde and glutaraldehyde reduced protein breakdown and carbohydrate fermentation during ensiling. The extent of protein protection afforded within the silo was similar for the two aldehydes, whereas formaldehyde was more effective in restricting carbohydrate fermentation. The effect of treatment FFG on silage fermentation was confounded by the silo bag bursting and the development of a clostridial-type fermentation. All aldehyde treatments reduced silage soluble-N content but N disappearance when the silages were incubated in polyester bags in the rumen was high for all silages and reductions due to the aldehydes were small. Silage digestion was studied in four mature sheep each fitted with a rumen cannula and re-entrant cannulas in the proximal duodenum and distal ileum. The apparent digestibility of organic matter (OM) in the whole tract was reduced (P less than 0.05) to a similar extent by both aldehydes, whereas rumen OM digestion was reduced (P less than 0.05) more by glutaraldehyde than by formaldehyde. The effects on digestion appeared to be due to the action of the aldehydes on the foods rather than to any adverse influences of the aldehydes on the metabolism of the rumen microbes because, although rumen ammonia levels were lower (P less than 0.05) when the aldehyde-treated silages were given, rumen casein-degrading activity, the degradation of different feedstuffs when incubated in polyester bags in the rumen and microbial N flow at the duodenum did not differ (P greater than 0.05) between silages. All aldehyde treatments decreased (P less than 0.05) the apparent digestibility of N in the whole tract. Silage N degradability in the rumen was also decreased (P less than 0.05) from 0.82 for silage F to 0.67, 0.60 and 0.62 for silages FF, FG and FFG respectively, and consequently non-ammonia-N (NAN) flow at the duodenum increased (P less than 0.05). The aldehydes did not adversely affect the apparent digestibility of NAN in the small intestine, and net NAN absorption from the small intestine increased from 8.8 g/d with silage F to 11.4, 15.3 and 14.2 g/d with silages FF, FG and FFG respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Aldehydes↗