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PubMed1991

Saccharomyces cerevisiae null mutants in glucose phosphorylation: metabolism and invertase expression.

A congenic series of Saccharomyces cerevisiae strains has been constructed which carry, in all combinations, null mutations in the three genes for glucose phosphorylation: HXK1, HXK2 and GLK1, coding hexokinase 1 (also called PI or A), hexokinase 2 (PII or B), and glucokinase, respectively: i.e., eight strains, all of which grow on glucose except for the triple mutant. All or several of the strains were characterized in their steady state batch growth with 0.2% or 2% glucose, in aerobic as well as respiration-inhibited conditions, with respect to growth rate, yield, and ethanol formation. Glucose flux values were generally similar for different strains and conditions, provided they contained either hexokinase 1 or hexokinase 2. And their aerobic growth, as known for wild type, was largely fermentative with ca. 1.5 mol ethanol made per mol glucose used. The strain lacking both hexokinases and containing glucokinase was an exception in having reduced flux, a result fitting with its maximal rate of glucose phosphorylation in vitro. Aerobic growth of even the latter strain was largely fermentative (ca. 1 mol ethanol per mol glucose). Invertase expression was determined for a variety of media. All strains with HXK2 showed repression in growth on glucose and the others did not. Derepression in the wild-type strain occurred at ca. 1 mM glucose. The metabolic data do not support- or disprove-a model with HXK2 having only a secondary role in catabolite repression related to more rapid metabolism.

Gene Expression Regulation, Fungal↗
PubMed2004

Laschiatrion, a new antifungal agent from a Favolaschia species (Basidiomycetes) active against human pathogens.

Laschiatrion (1), a new antifungal antibiotic, was isolated from fermentations of Favolaschia sp. 87129. (1) exhibits broad in vitro activity against several human pathogens while no antibacterial and cytotoxic activities could be detected. The structure was elucidated by spectroscopic techniques. As to our knowledge laschiatrion possesses a new steroid skeleton.

Antifungal Agents↗
PubMed2003

Wood ingestion by passalid beetles in the presence of xylose-fermenting gut yeasts.

During a survey of insect gut micro-organisms, we consistently isolated Pichia stipitis-like yeasts (Fungi: Ascomycota, Saccharomycetes) from the wood-ingesting beetles, Odontotaenius disjunctus and Verres sternbergianus (Coleoptera: Passalidae). The yeasts were isolated from passalid beetles over a wide area, including the eastern and midwestern USA and Panama. Phylogenetic analyses of the nuclear encoded small and large subunit rRNA gene (rDNA) sequences distinguished a well-supported clade consisting of the passalid yeasts and Pichia stipitis, P. segobiensis, Candida shehatae and C. ergatensis. Members of this clade have the ability to ferment and assimilate xylose or to hydrolyse xylan, major components of the polysaccharide, hemicellulose. Sexual reproduction was present in the passalid isolates but was rare among the gut yeasts of other beetles to which they were compared. Minor genetic and phenotypic variation among some of the passalid yeasts was detected using markers from the internal transcribed spacer region of the rDNA repeat unit, morphology, and in vitro metabolic tests. The consistent association of xylose-fermenting yeasts of almost identical genotypes with passalid beetles across a broad geographical distribution, suggests a significant symbiotic association.

Animals↗
PubMed2006

The use of microorganisms in L-ascorbic acid production.

L-Ascorbic acid has been industrially produced for around 70 years. Over the past two decades, several innovative bioconversion systems have been proposed in order to simplify the long time market-dominating Reichstein method, a largely chemical synthesis by which still a considerable part of L-ascorbic acid is produced. Here, we describe the current state of biotechnological alternatives using bacteria, yeasts, and microalgae. We also discuss the potential for direct production of l-ascorbic acid exploiting novel bacterial pathways. The advantages of these novel approaches competing with current chemical and biotechnological processes are outlined.

Ascorbic Acid↗
PubMed2003

Lactic acid bacteria: inhibition of angiotensin converting enzyme in vitro and in vivo.

A total of 26 strains of wild-type lactic acid bacteria, mainly belonging to Lactococcus lactis and Lactobacillus helveticus, were assayed in vitro for their ability to produce a milk fermentate with inhibitory activity towards angiotensin converting enzyme (ACE). It was clear that the test strains in this study, in general, produce inhibitory substances in varying amounts. Using a spectrophotometric assay based on amino group derivatization with ortho-phthaldialdehyde as a measure of relative peptide content, it was shown that there is a significant correlation between peptide formation and ACE inhibition, indicating that peptide measurement constitutes a convenient selection method. The effect of active fermentates on in vivo ACE activity was demonstrated in normotensive rats. The pressor effect of angiotensin I (0.3 microg/kg) upon intravenous injection was significantly lower when rats were pre-fed with milks fermented using two strains of Lactobacillus helveticus. An increased response to bradykinin (10 microg/kg, intravenously injected) was observed using one of these fermented milks. It is concluded that Lactobacillus helveticus produces substances which in vivo can give rise to an inhibition of ACE. The inhibition in vivo was low compared to what can be achieved with classical ACE inhibitors. The clinical relevance of this finding is discussed. This work is the first in which an effect of fermented milk on ACE in vivo has been demonstrated, measured as decreased ability to convert angiotensin I to angiotensin II.

Angiotensin I↗
PubMed2006

Peptide YY and proglucagon mRNA expression patterns and regulation in the gut.

OBJECTIVE: Peptide YY (PYY) and glucagon-like peptide-1 are important in the control of energy homeostasis and are both secreted from the gut in response to ingested nutrients. However, more studies are needed on nutrient regulation of their gene expression patterns in specific areas of the gut. This study detailed PYY and proglucagon (the gene that encodes glucagon-like peptide-1) gene expression patterns and regulation in the gut. We further examined the regulation of PYY and proglucagon mRNA by a diet containing fermentation-resistant starch (in vivo) and butyrate (in vitro). RESEARCH METHODS AND PROCEDURES: Quantitative real time reverse transcriptase-polymerase chain reaction was used to measure PYY and proglucagon gene expression in epithelial cells collected from the duodenum, jejunum, cecum, and colon in normal Sprague-Dawley rats and in rats fed a resistant starch diet for 4 weeks. The same measurements were also performed in primary epithelial cells collected from the cecum and colon of normal rats after the cells were incubated with butyrate for 3 hours. RESULTS: The gene expression patterns for PYY and proglucagon are similar to their peptide distribution patterns in the gut. Also, PYY and proglucagon mRNA expression were up-regulated in the cecum and colon in resistant-starch-fed rats. Butyrate increased PYY and proglucagon gene expression in a dose-dependent manner in vitro. DISCUSSION: Our data provide evidence that the distal part of the gut has the ability to sense nutrients such as butyrate, resulting in the up-regulation of PYY and proglucagon gene expression.

Animals↗
PubMed1988

Production of volatile fatty acids as a result of bacterial interactions in the cecum of gnotobiotic rats and chickens fed a lactose-containing diet.

Volatile fatty acid (VFA) productions from lactose and lactate by a Clostridium butyricum and a Veillonella alcalescens strain, alone or in combination with a Lactobacillus acidophilus strain, were determined both in vitro in culture media and in vivo in the ceca of gnotobiotic animals. Gnotobiotic rats, which possess intestinal lactase, and chickens, which are devoid of it, were used. Both animal species were fed a diet containing 4% lactose. The in vitro results showed that the C. butyricum strain fermented lactose and D-lactic acid to butyric and acetic acids, whereas L-lactic acid was not fermented. The V. alcalescens strain did not ferment lactose and fermented L better than D-lactic acid. The in vivo results showed that high VFA concentrations were obtained in the ceca of chickens either disassociated with V. alcalescens or C. butyricum and Lactobacillus strains or monoassociated with C. butyricum. VFA concentrations in the ceca of rats were low, whatever strain the rats harbored. In addition, an antagonistic effect of the C. butyricum strain against the Lactobacillus strain was evidenced both in rats and chickens. It is suggested that the absence of a host lactase makes the chick a good model for lactose intolerance studies in human newborns.

Anaerobiosis↗
PubMed2006

Gene expression profiles of different breast cancer cells compared with their responsiveness to fermented mistletoe (Viscum album L.) extracts Iscador from oak (Quercus), pine (Pinus), white fir (Abies) and apple tree (Malus) in vitro.

Cytotoxicity assays in vitro (MTT test) showed that the different breast cancer cell lines Kpl-1, MCF-7 and Mfm-223 respond differently to the mistletoe (Viscum album L.) preparations Iscador. Quercus (Qu), Abies (A), Malus (M) and Pinus (P). In order to determine the differences in the responsiveness of the cells more exactly, the gene expression profiles were determined by cells, which were treated with Mistletoe extracts, compared with untreated control cells. Such differences can be analysed in more detail by looking at the gene expression using Human Whole Genome microarray chips (41,000 genes). The results of the transcriptome analyses suggested that Iscador preparations influenced the overregulation of genes regarding immune defense, stress response, apoptosis and cell-cell adhesion pathways. Within the Mfm-223-Zellen was the Genexpression in MCF-7 and Kpl-1. The MCF-7 cells were affected on the genes which are involved in cell-cell contacts whereas Kpl-1 responded to the mistletoe extracts by changing the mRNA levels of the immune and stress response pathways. Concerning the effects of the mistletoe extract, we conclude that Iscador Qu and M have a greater influence on the immune defense and stress response genes whereas Iscador A tends to affect the cell-cell adhesion and cytoskeleton pathways. In summary, cDNA microarray analyses give us information on whether a cancer cell is sensitive to mistletoe extracts in relation to how many genes are significantly overrepresented after mistletoe treatment, and whether a particular mistletoe extract is more effective on a specific cancer cell than the other preparation.

Abies↗
PubMed1976

Methane production and digestibility measurements in the grey kangaroo and sheep.

Three grey knagaroos and three sheep were given a diet of lucerne chaff and measurements were made of feed intake, digestibility coefficients, methane production rate and volatile fatty acid content of the "stomach" and caecum for each animal. The kangaroos had lower intakes of digestible dry matter and organic matter than the sheep; this was related to lower intakes of dry matter and lower apparent digestibility coefficients particularly of the crude fibre fraction. Methane production in the sheep (collected in respired air through a mask) was 0-81 litre/h; no methane was collected in the respired air from kangaroos. Anal release of methane in sheep and kangaroos indicated that some methane was produced in the hind gut of kangaroos and that all of this methane was lost via the anus. This finding was different to the sheep which apparently excreted 80-90% of the hind gut methane via the lungs. Thus in both sites of apparent high microbial growth in the gut of kangaroos methane production is negligible or lower than in the same sites in sheep. Possible explanations for the absence of measurable methane production in the kangaroo fore-stomachs are discussed.

Anal Canal↗
PubMed2004

Bifidobacterium animalis strain DN-173 010 hydrolyses bile salts in the gastrointestinal tract of pigs.

BACKGROUND: Bile salt hydrolase (BSH) activity is widespread among ingested bifidobacteria and lactobacilli. It is sometimes considered to be beneficial because of its putative lowering effect on cholesterol absorption and sometimes considered to be deleterious because it may compromise normal fat absorption and even promote the formation of secondary cytotoxic bile acids by the resident intestinal flora. However, the true hydrolysis of bile salts in vivo by ingested living bacteria remains unexplored. The aim of the study was to examine whether or not Bifidobacterium animalis DN-173 010 (used in fermented milks), which demonstrates a BSH activity in vitro, was also active in vivo during its transit in the intestine of pigs. METHODS: Direct measurement of total and unconjugated bile acids reabsorbed into the portal vein was done, before and after the pigs had been treated for 2 weeks with two daily doses of approximately 3.5 x 10(11) colony-forming units of living (6 pigs) or inactivated B. animalis (6 pigs). RESULTS: None of the treatments modified the portal serum concentration of total bile acids over a 6-h postprandial period. Unconjugated bile acids represented up to 44% and 53% of total bile acids after 1 and 2 weeks of treatment with living bacteria, respectively, compared with only 25% (P < 0.05) before treatment or after 1 or 2 weeks of treatment with inactivated bacteria. CONCLUSIONS: Living B. animalis DN-173 010 exhibited a BSH activity in the gastrointestinal tract of pigs, most probably in the small bowel. There was no sign of increased formation of secondary bile acids beyond the hydrolysis reaction.

Animals↗
PubMed1997

Antiproliferative effect of fermented milk on the growth of a human breast cancer cell line.

In vivo and in vitro studies have shown an antitumor activity of Lactobacilli in colon cancer, and some epidemiologic studies have indicated a reduced risk of breast cancer in women who consume fermented milk products. We studied the direct effect of milk fermented by five bacteria strains (Bifidobacterium infantis, Bifidobacterium bifidum, Bifidobacterium animalis, Lactobacillus acidophilus, and Lactobacillus paracasei) on the growth of the MCF7 breast cancer cell line. Our results showed a growth inhibition induced by all fermented milks, even though B. infantis and L. acidophilus were the most effective (85% inhibition after 9 days). The antiproliferative effect was not related to the presence of bacteria in fermented milk, and neither whole milk (crude or ultrahigh temperature sterlizied) nor its main fractions (lactalbumin or beta-lactoglobulin fraction) affected cell growth. Our findings suggest the presence of an ex novo soluble compound produced by lactic acid bacteria during milk fermentation or the microbial transformation of some milk components in a biologically active form. Although the mechanism of the antitumor activity is not clear, the present study suggests the potentiality offered by fermented milk as producers of compounds with antiproliferative activity useful in the prevention and therapy of solid tumors like breast cancer.

Animals↗
PubMed1992

Effect of monensin on fermentation of hay and wheat bran investigated by the Rumen Simulation Technique (Rusitec). 2. End-products of fermentation and protein synthesis.

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 supplemented with 2.5 and 10 mg monensin. The duration of the experiment was 12 days. During the first six days the fermentation conditions in Rusitec were stabilised. The end products of fermentation and indices of protein synthesis were determined. The energy efficiency of volatile fatty acids (VFA), proportion of fermented hexose energy on VFA energy and on energy of bacterial matter were increased in the presence of monensin. The proportion of fermented hexose energy in methane energy was decreased. Utilization of glucose and production of adenosine triphosphate were not affected. The balance of metabolic H2 was reduced and this was manifested in decreasing production, utilization and recovery of metabolic H2. Microbial efficiency expressed per mol ATP (g/mol) was increased by monensin from 7.8 to 12.6. The indices of protein synthesis--protein conversion ratio, degradability of protein and microbial protein synthesis efficiency were increased and non protein utilization ratio decreased in the presence of monensin.

Animal Feed↗
PubMed2003

The effect of 5-aminosalicylic acid-containing drugs on sulfide production by sulfate-reducing and amino acid-fermenting bacteria.

The toxic, bacterial metabolite sulfide is implicated in ulcerative colitis. Ulcerative colitis patients taking 5-aminosalicylic acid-containing drugs have lower fecal sulfide levels than those not taking these drugs. The effects of sulfasalazine, balsalazide, olsalazine, and 5-aminosalicylic acid on sulfide production were studied in a three-stage chemostat pulsed on days 1 to 3 with 5 g sulfasalazine (40 mM) and in pure cultures of amino acid-fermenting and sulfate-reducing bacteria. By the third day of sulfasalazine addition to the chemostat, sulfide concentrations in vessels 1 through 3 had dropped from 1.73, 1.78, and 1.43 mM to 0.01, 0.15, and 0.9 mM, respectively. In pure cultures, 50% inhibition of sulfide production from amino acids occurred at 2.5 +/- 0.05 mM for sulfasalazine, 5 +/- 0.2 mM for olsalazine, 6 +/- 1 mM for balsalazide, and more than 20 mM for 5-aminosalicylic acid. Fifty percent inhibition of sulfide production from sulfate occurred at 0.25 +/- 0.05 mM for sulfasalazine, 0.7 +/- 0.2 mM for balsalazide, and 9.0 +/- 1.0 mM for 5-aminosalicylic acid. The order of effectiveness of equimolar concentrations of drugs (most effective first) in this assay was sulfasalazine, then olsalazine (though given clinically at half the dose of other 5-aminosalicylic acid prodrugs) and balsalazide, and lastly 5-aminosalicylic acid. Inhibition of sulfide production by 5-aminosalicylic acid-containing drugs may contribute to their therapeutic effect in ulcerative colitis.

Amino Acids↗
PubMed1965

Production of calcium gluconate by Penicillium chrysogenum in submerged culture.

The waste mycelium of Penicillium chrysogenum HA-10 (obtained at the end of penicillin fermentation), or a 24-hr-old freshly grown vegetative inoculum of this organism, was found to utilize glucose for the production of calcium gluconate by submerged fermentation in shake flasks. After 72 to 96 hr of fermentation at 24 C, 90 to 95% of the reducing sugar from the 15% glucose medium was converted to calcium gluconate. Reuse of the mycelium for successive experiments reduced the fermentation period to 72 hr or less because of an enhancement of glucose utilization. Ten successive batches of 15% glucose medium were fermented by the reuse method. Fermentation media containing up to 30% glucose could be used, provided boric acid was added to prevent the precipitation of calcium gluconate formed. We found that 30% hydrol (a by-product of glucose manufacture containing 50 to 55% reducing sugar), when used in place of glucose in the fermentation medium, inhibited the rate of glucose utilization. However, this effect was partially reversed by pretreatment of hydrol with 2 to 4% activated charcoal before addition to the fermentation medium.

Bacteriological Techniques↗