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PubMed1989

[Selected properties of lactose-fermenting and non-fermenting Salmonella agona strains isolated from specimens from hospitalized infants].

The aim of this study was to compare some of the properties of 28 lactose-positive and 28 lactose-negative Salmonella agona strains isolated from faeces of infants hospitalized in the same hospital. Some of biochemical properties, sensitivity to 14 antibiotics and chemotherapeutic agents and sensitivity to bacteriophages used for typing of this Salmonella genus were tested. Results of biochemical examinations revealed that lactose-fermenting strains retain the remaining of Salmonella of subspecies I. Two biochemical features are of particular importance: the ability to ferment lactose on all lactose containing media and a lack of the ability to produce H2S on Kligler medium. These two features differentiate lactose-fermenting strains of Salmonella from non-lactose fermenting ones. Antibiotic sensitivity pattern differed between lactose-positive and lactose-negative strains. Lactose-positive strains showed higher degree of resistance than lactose-negative strains. The differences in resistance were seen in the case of chloramphenicol, doxycycline, gentamicin and tetracycline. Both lactose-positive and lactose-negative strains were sensitive to colistin, neomycin, nitrofurantoin and nalidixic acid. They were resistant to ampicillin, cloxacillin, rifampicin, streptomycin, sulfatiazol and biseptol. Bacteriophage typing revealed that all lactose-negative strains isolated in this study from clinical samples belonged to the same phage pattern V. Lactose-positive strains belonged to two phage types VB and XI. Type VB prevailed.

Anti-Bacterial Agents↗
PubMed2003

Analysis of 16S rDNA reveals bacterial shift during in vitro fermentation of fermentable carbohydrate using piglet faeces as inoculum.

In vitro fermentation of sugar beet pulp (SBP) was carried out to determine which bacterial species would be enriched by use of this carbohydrate source. Faeces from four weaning piglets as a source of inoculum was also compared. The microbial diversity of the prominent bacteria before and after this in vitro fermentation was analysed using denaturing gradient gel electrophoresis (DGGE) of PCR amplicons of 16S rDNA. Before fermentation, the DGGE profiles showed differences between cultures inoculated with faeces from different piglets, though some bands were common to all piglets. After fermentation of SBP, three dominant bands appeared, of which two bands appeared in all samples and one for both replicates of one piglet. Sequences of the corresponding 16S rDNA of two bands showed 92% similarity to Eubacterium eligens and 96% similarity to Lachnospira pectinoschiza, and that of the third band 95% to L. pectinoschiza.

Journal Article↗
PubMed2002

Modification of the acetaldehyde concentration during alcoholic fermentation and effects on fermentation kinetics.

We studied the kinetic effects of increasing the residual acetaldehyde concentration during alcoholic fermentation, especially during the stationary phase. We added this compound via pulse or continuous injections. The yeast response depended on the amount of acetaldehyde added: high concentrations inhibited fermentation while low concentrations led to stimulation. When regular small additions were made, up to 100 mM acetaldehyde could be added and this caused a very significant drop in the fermentation duration. We also modulated the acetaldehyde concentration by modifying the alcohol dehydrogenase-catalyzed reaction. Two approaches were tested (i) adding aldehydes (propanal and furfural) that competitively inhibited the reduction of acetaldehyde and (ii) adding electron acceptors that reduced the quantity of NADH available. Several possible mechanisms responsible for (i) the impact of acetaldehyde on fermentation kinetics and (ii) the modulation of the residual acetaldehyde concentration are discussed.

Journal Article↗
PubMed2004

Fermentation performance of engineered and evolved xylose-fermenting Saccharomyces cerevisiae strains.

Lignocellulose hydrolysate is an abundant substrate for bioethanol production. The ideal microorganism for such a fermentation process should combine rapid and efficient conversion of the available carbon sources to ethanol with high tolerance to ethanol and to inhibitory components in the hydrolysate. A particular biological problem are the pentoses, which are not naturally metabolized by the main industrial ethanol producer Saccharomyces cerevisiae. Several recombinant, mutated, and evolved xylose fermenting S. cerevisiae strains have been developed recently. We compare here the fermentation performance and robustness of eight recombinant strains and two evolved populations on glucose/xylose mixtures in defined and lignocellulose hydrolysate-containing medium. Generally, the polyploid industrial strains depleted xylose faster and were more resistant to the hydrolysate than the laboratory strains. The industrial strains accumulated, however, up to 30% more xylitol and therefore produced less ethanol than the haploid strains. The three most attractive strains were the mutated and selected, extremely rapid xylose consumer TMB3400, the evolved C5 strain with the highest achieved ethanol titer, and the engineered industrial F12 strain with by far the highest robustness to the lignocellulosic hydrolysate.

Cellulose↗
PubMed1990

Efficient simultaneous saccharification and fermentation of agricultural residues by Saccharomyces cerevisiae and Candida shehatae. The D-xylose fermenting yeast.

Simultaneous Saccharification and Fermentation (SSF) experiments were carried out on agricultural residues using culture filtrate of Sclerotium rolfsii, which produces high levels of cellulases and hemicellulases for the saccharification of rice straw and bagasse, and Candida shehatae--the D-xylose fermenting yeast, and Saccharomyces cerevisiae, both separately and in coculture, for fermenting the released sugars. The coculture system showed efficient utilization of hydrolyzed sugars with 30-38% and 10-13% increase in ethanol production as compared to C. shehatae and S. cerevisiae, respectively, when cultivated separately. SSF simulation studies were carried out using standard sugar mixtures of glucose, xylose, and cellobiose. Both organisms could not use cellobiose, whereas glucose was used preferentially. C. shehatae was capable of utilizing xylose in the presence of glucose.

Candida↗
PubMed2003

Microbiological and fermentation characteristics of togwa, a Tanzanian fermented food.

Selected microbiological and metabolic characteristics of sorghum, maize, millet and maize-sorghum togwa were investigated during natural fermentation for 24 h. The process was predominated by lactic acid bacteria (LAB) and yeasts. The mesophiles, lactic acid bacteria, and yeasts increased and the Enterobacteriaceae decreased to undetectable levels within 24 h. The isolated microorganisms were tentatively identified as Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus cellobiosus, Pediococcus pentosaceus, Weissella confusa, Issatchenkia orientalis, Saccharomyces cerevisiae, Candida pelliculosa and Candida tropicalis. The pH decreased from 5.24-5.52 to 3.10-3.34. Maltose increased initially and then decreased, fructose decreased and glucose levels increased during the first 12 h of fermentation. The organic acids detected during fermentation included DL-lactic, succinic, formic, pyruvic, citric, pyroglutamic and uric acid. Lactate was the predominant acid and increased significantly with time. The volatile organic compounds (VOC) detected included acetaldehyde, 2-methyl-propanal, 2-methyl-butanal, 3-methyl-butanal, ethanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, diacetyl and acetoin. Ethanol was the predominant VOC and it increased significantly with time.

Candida↗
PubMed2002

Effect of different forms of alkali treatment on specific fermentation inhibitors and on the fermentability of lignocellulose hydrolysates for production of fuel ethanol.

Treatment with alkali, particularly overliming, has been widely used as a method for the detoxification of lignocellulose hydrolysates prior to ethanolic fermentation. However, the mechanisms behind the detoxification effect and the influence of the choice of cation have not been well understood. In this study, a dilute acid hydrolysate of spruce and an inhibitor cocktail consisting of six known inhibitors were used to investigate different alkali detoxification methods. The various treatments included the addition of calcium hydroxide, sodium hydroxide, potassium hydroxide, and ammonia to pH 10.0 and subsequent adjustment of the pH to 5.5 with either sulfuric or hydrochloric acid as well as treatment with the corresponding amounts of calcium, sodium, and potassium as sulfate or chloride salts at pH 5.5. An RP-HPLC method was developed for the separation of 18 different inhibitors in the hydrolysate, including furaldehydes and phenolics. Detection and quantification were carried out by means of UV, DAD, and ESI-MS in negative mode. Treatment of the spruce hydrolysate with alkali resulted in up to approximately 40% decrease in the concentration of furaldehydes. The effects on the aromatic compounds were complex. Furthermore, SFE was performed on the precipitate formed during alkali treatment to evaluate the inhibitor content of the precipitate, and the following RP-HPLC analysis implied that potential inhibitors were removed mainly through conversion rather than through filtration of precipitate. Parallel experiments in which sulfuric acid or hydrochloric acid was used for acidification to pH 5.5 after alkali treatment indicated that the choice of anion did not affect the removal of inhibitors. Detoxification with calcium hydroxide and ammonia resulted in better fermentability using Saccharomyces cerevisiae than detoxification with sodium hydroxide. The results from the experiments with the inhibitor cocktail indicated that the positive effects of alkali treatment are difficult to explain by removal of the inhibitors only and that possible stimulatory effects on the fermenting organism warrant further attention.

Acetic Acid↗
PubMed1990

[Extent and effect of fermentation in the large intestine of swine. 1. Ileal flow rate, fermentation ability and colon capacity].

Colonic events (volumina, fermentability, rate of passage) were determined in a complex program with young sows using 8 rations. Ileal cannulated sows were used and 4 slaughtered animals per ration to study volumina contents and to take samples for in vitro fermentation. The results are compared with 81 former experiments using ileal cannulated sows. Ileal nutrient flow was very different in quality and quantity. It varied between 1674 and 520 g OM/d, affecting seriously postileal reactions. Volumina of large intestine varied between 10 and 25 litres or between 83 and 226 ml/kg LW being determined by ileal flow rate (B = 0.90). The flow rate influenced also transit time (B = 0.89). Fermentability of OM in average come to 60% (from 33 to 77%) according to ileal flow composition.

Animal Feed↗
PubMed1992

Effect of monensin on fermentation of hay and wheat bran investigated by the Rumen Simulation Technique (Rusitec). 1. Basal parameters of fermentation.

An experiment was performed with Rumen Simulation Technique (Rusitec) in which the fermentation of mixed ration of hay (12.8 g/d) and wheat bran (3.2 g/d) was compared with the fermentation of the same diet in the presence of 2, 5 and 10 mg of monensin/d. The duration of the experiment was 12 days. During the first six days the fermentation conditions in Rusitec were stabilized. Monensin significantly depressed the digestibility of dry matter and fibre digestion--neutral detergent fibre (NDF), acid detergent fibre (ADF) and cellulose but only after using 2 mg monensin/d. Addition of monensin depressed the production of VFAs--acetate, butyrate and isovalerate and acetate:propionate ratio. Production of propionate was increased and production of methane and CO2 was decreased in the presence of monensin. It can be explained by changes in the production of VFAs and redistribution of metabolic hydrogen. The recovery of nitrogen was satisfactory (about 100%) and its distribution in the effluent was increased by monensin. The recovery of protein (measured as alpha--NH2 groups) and distribution of protein in the effluent and residues was increased with the increasing dose of monensin.

Animal Feed↗
PubMed1998

Protein modification by fermentation: effect of fermentation on the potential allergenicity of pea.

The effect of fermentation on components of potential significance for the allergenicity of pea was analyzed. Pea flour was fermented with three lactic acid bacteria, Pediococcus pentosaceus, Lactococcus raffinolactis, and Lactobacillus plantarum, and two fungi, Rhizopus microsporus, var. oligosporus and Geotrichum candidum. Residual antigenicity against antipea antibodies was reduced to 10% by the three lactic acid bacteria and R. microsporus. Reactions to anti-pea profilin and anti-Bet v 1 were still detectable after fermentation. The contents of lectin and pea protease inhibitor were not reduced by the microorganisms.

Animals↗
PubMed1982

Effect of fermentation on lactose, glucose, and galactose content in milk and suitability of fermented milk products for lactose intolerant individuals.

The lactose, glucose, and galactose content in various fermented milk products was studied by enzymatic methods. Lactose was decreased in all fermented products. After 11 days storage of yogurt the lactose content decreased to about 2.3 g/100 compared to 4.8 g/100 g in nonfermented milk. During the same period, galactose content increased from traces in milk to 1.3 g/100 g in yogurt. Results were similar with acidophilus and bifidus milk. Buttermilk, kefir, and ropy milk showed 26, 30, and 20% decreases in lactose content. Eight lactose intolerant individuals showed symptoms of abdominal distress and diarrhea following consumption of 500 ml of low fat milk whereas ingestion of the same quantity of yogurt or acidophilus milk did not result in any symptoms. Fermented milk products should be considered in formulating diets for lactose-intolerant subjects.

Adolescent↗
PubMed1998

[Study on immobilized cells for producing alpha-amylase by using polyving alcohol as the carrier(II): The effect of fermentating conditions on the ability producing alpha-amylase of the cells immobilized with polyving alcohol as the corrier and continuous fermentation of the immobilized cells in CSTR].

The effects of fermentating conditions on the ability of immobilized cells with PVA as carrier for producing alpha-amylase were studied. The continuous fermentation with the immobilized cells were tested in continuous flow stirred tank reactor (CSTR). The results showed that the adaptability of the immobilized Bacillus substilis to pH increased after immobilization. In CSTR, the immobilized cells can be fermentated continuously for 360 hrs and the activity of alpha-amylase can be kept on the level of about 170 u/ml.

Bacillus↗
PubMed2001

Characterisation of the gastrointestinal bacterial community in pigs fed fermented liquid feed and dry feed: composition and fermentation capacity (phenotypic fingerprint).

Feeding pigs with fermented liquid feed (FLF) has been shown to reduce the number of enteropathogens such as Salmonella and Brachyospira hyodysenteriae as well as coliform bacteria in general in the gastrointestinal tract (GIT). Also the commensal bacterial populations have been shown to respond to the use of FLF, e.g. the total counts of anaerobes, including lactic acid bacteria are reduced. In the present work we demonstrate that the capacity to ferment a series of substrates (mainly low-molecular weight carbohydrates) is reduced in caecum, colon and faeces of pigs fed FLF compared to pigs fed dry feed. This reduction could be due to the fact that these substrates are partially depleted by fermentation in the liquid feed prior to entering the animal. Therefore nutrient availability may be limited in the large intestine of pigs fed FLF, which may again affect bacterial enzyme synthesis and growth and thus the possibility for pathogenic and zoonotic bacteria to establish.

Animal Feed↗
PubMed2006

[The fermentation of 50 kinds of TCMs by Bacillus subtilis and the assay of antibacterial activities of fermented products].

50 Traditional Chinese medicines (TCMs) were fermented by Bacillus subtilis and the antimicrobial activities of the fermented products were assayed against Mycobacterium tuberculosis and Penicillium avellaneum. The results showed that some products of them had stronger antimicrobial activities, but some weaker than the corresponding raw materials, still some had no change, which indicated that microorganism and TCM can effect each other during fermentation.

Anti-Bacterial Agents↗
PubMed1990

[Intestinal syndrome of absent fermentation in swine after liquid feeding of easily-fermentable components].

Intestinal dysfermentation with diarrhea, tympania and accidental cases of sudden death in the pig after liquid feeding of components highly fermentable. 6 cases of the veterinary feeding advisement of the Institute of animal nutrition are presented, which can be described with the complex of symptoms: diarrhea, bloat, sudden death. These are related to feeding technique, feed composition and hygienic quality of the feed. All techniques of feeding, causing abundant feed intake and thus an exceeding of the digestive capacity of the gut are a predisposition for fermentative disturbances. A high level of feed hygiene can only be maintained in liquid feeding systems by high efforts concerning cleaning. A reduced hygienic feed quality in all present cases was apparent. All rations had a high content of easily fermentable components (sugar, partially enzymatically predigested starch). The clinical symptoms correspond to the well known "whey-syndrome". They are however not strictly correlated to rations with high whey contents. The prophylactic procedure especially concerns the improvement of the hygienic feed quality, the feeding technique and the addition of acids.

Animal Feed↗
PubMed2004

On-line monitoring of important organoleptic methyl-branched aldehydes during batch fermentation of starter culture Staphylococcus xylosus reveal new insight into their production in a model fermentation.

A small fermentor (55 mL) was directly interfaced to a membrane inlet mass spectrometer for continuous on-line monitoring of oxygen and volatile metabolites during batch fermentations of the starter culture Staphylococcus xylosus. Using this technique, we were able to correlate production of the very important flavor compounds 2-methylbutanal, 3-methylbutanal, and 2-methylpropanal with various growth conditions. We found that the aldehydes were present in the culture broth only as transient metabolites. They were produced in the exponential growth phase, reached a maximum concentration when the culture became anaerobic, and then they rapidly disappeared from the culture medium. This general pattern was observed for three different strains of S. xylosus and S. carnosus. Small amounts of inoculum or increased exposure to oxygen were found to favor production of the aldehydes as a result of a longer aerobic growth period. Growing S. xylosus under conditions resembling those in a fermented sausage revealed that NaCl (5%) increased aldehyde production considerably, whereas KNO(3) (0.03%) or NaNO(2) (0.03%) had little effect. A lowering of pH from 7.2 to 6.0 reduced cell density, but had a minor affect on aldehyde production.

Aldehydes↗
PubMed1988

MAL64c is a global regulator of alpha-glucoside fermentation: identification of a new gene involved in melezitose fermentation.

Maltase constitutive mutants at the MAL6 locus have been mapped to the newly identified regulatory gene MAL64c. We show here that MAL64c has in addition pleiotropic effects on sugar fermentation: MAL64c strains constitutively synthesize an alpha-methylglucosidase and can complement a new gene, MTP1, for the fermentation of melezitose and alpha-methylglucoside. MTP1, maps near MAL1, and either encodes a permease which transports melezitose, alpha-methylglucoside, and maltose or regulates the activity of such a permease. This work shows that MAL64c, a trans-acting regulatory gene, is a global regulatory gene affecting several different pathways of alpha-glucoside metabolism.

Alleles↗
PubMed1996

Peculiarities of the regulation of fermentation and respiration in the crabtree-negative, xylose-fermenting yeast Pichia stipitis.

The respiration of Pichia stipitis was not repressed by either high concentrations of fermentable sugars or oxygen limitation. Fermentation was not induced by high sugar concentrations, but was inactivated by aerobic conditions. The activity of pyruvate dehydrogenase was constitutive. In contrast, pyruvate decarboxylase, alcohol dehydrogenase, and aldehyde dehydrogenase were induced by a reduction in the oxygen tension. It was demonstrated that in P. stipitis, the pyruvate decarboxylase is not induced by a signal from glycolysis. Contrary to Saccharomyces cerevisiae, the pyruvate decarboxylase was not inhibited by phosphate.

Alcohol Dehydrogenase↗