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PubMed1991

Cloning of a beta-glucosidase gene from Ruminococcus albus and its expression in Escherichia coli.

A HindIII fragment of R. albus DNA encoding beta-glucosidase was cloned into E. coli. The DNA sequence (3158 bp) was determined, and the longest potential encoding sequence consisted of 2,841 bp (947 amino acids with the calculated molecular weight of 104,276. The deduced NH2-terminal amino acid sequence from the first (methionine) to the twentieth (glycine) was identical to that of the purified enzyme, suggesting that the gene for beta-glucosidase does not encode a signal peptide. The enzyme purified from the culture supernatant of the transformant had a molecular weight of 120,000 and its maximum activity was revealed at pH 6.5 and 30 degrees C. Reducing reagents activated the enzyme, whereas the sulfhydryl group-blocking reagents and reaction products (glucose) inhibited the activity. Hydrolyzates of celloorigomers contained glucose as a major product, indicating that the enzyme acts as beta-glucosidase. The enzyme from the transformant revealed similar properties to that from R. albus, and both enzyme proteins were immunologically the same to each other, indicating that the cloned gene encodes beta-glucosidase from R. albus.

Amino Acid Sequence↗
PubMed1985

Mucin degradation in human colon ecosystems. Isolation and properties of fecal strains that degrade ABH blood group antigens and oligosaccharides from mucin glycoproteins.

We previously reported that the oligosaccharide chains of hog gastric mucin were degraded by unidentified subpopulations numbering approximately 1% of normal human fecal bacteria. Here we report on the enzyme-producing properties of five strains of mucin oligosaccharide chain-degrading bacteria isolated from feces of four healthy subjects. Four were isolated from the greatest fecal dilutions yielding mucin side chain-degrading activity in culture, and thus were the numerically dominant side chain-degrading bacteria in their respective hosts. Three were Ruminococcus strains and two were Bifidobacterium strains. Two Ruminococcus torques strains, IX-70 and VIII-239, produced blood group A- and H-degrading alpha-glycosidase activities, sialidase, and the requisite beta-glycosidases; these strains released greater than 90% of the anthrone-reacting hexoses from hog gastric mucin during growth in culture. The Bifidobacterium strains lacked A-degrading activity but were otherwise similar; these released 60-80% of the anthrone-reacting hexoses but not the A antigenic structures from hog gastric mucin. Only Ruminococcus AB strain VI-268 produced blood group B-degrading alpha-galactosidase activity, but this strain lacked beta-N-acetylhexosaminidases to complete degradation of B antigenic chains. When this strain was co-cultured with a strain that produced beta-N-acetylhexosaminidases, release of hexoses from blood group B salivary glycoprotein increased from 50 to greater than 90%, and bacterial growth was enhanced. The glycosidases required for side chain degradation were produced by these strains in the absence of mucin substrate, and a substantial fraction of each activity in stationary phase cultures was extracellular. In contrast, none of 16 other fecal Bacteroides, Escherichia coli, Streptococcus faecalis, and Bifidobacterium strains produced ABH blood group-degrading enzymes; other glycosidases produced by these strains were predominantly cell bound except for extracellular beta-N-acetylhexosaminidases produced by the five S. faecalis strains. We conclude that certain Bifidobacterium and Ruminococcus strains are numerically dominant populations degrading mucin oligosaccharides in the human colon due to their constitutive production of the requisite extracellular glycosidases including blood group antigen-specific alpha-glycosidases. These properties characterize them as a functionally distinct subpopulation of normal human enteric microflora comprised of specialized subsets that produce blood group H antigen-degrading glycosidases alone or together with either blood group A- or B-degrading glycosidases.

ABO Blood-Group System↗
PubMed1977

Cellulolytic cocci isolated from the cecum of guinea pigs (Cavia porcellus).

Five strains of anaerobic, gram-variable cellulolytic cocci, belonging to the genus Ruminococcus, were isolated from the cecum of a guinea pig. They differed from most previously described strains of cellulolytic ruminococci as follows. (i) Lactate was the major fermentation product; lesser amounts of formate and ethanol and a trace of succinate were also produced, along with an uptake of acetate. (ii) No growth occurred at 30 degrees C; however, good growth was observed at 38 and 45 degrees C, (iii) Glucose, cellobiose, cellulose, xylose, arabinose, xylan, sucrose, and lactose were fermented by all strains. Rumen fluid was required for growth in a complete medium containing all nutrients previously found to be required by species in this genus. Limited growth occurred when rumen fluid was replaced by yeast extract, and maximum, but delayed, growth occurred when a water extract of alfalfa was added to the complete medium. No qualitative differences were found in the cell wall amino acids and sugar composition of these strains as compared to Ruminococcus flavefaciens and Ruminococcus albus; however, cell walls of the guinea pig strains appeared to contain a higher proportion of glucose.

Acetates↗
PubMed1977

Fermentation of mucins and plant polysaccharides by anaerobic bacteria from the human colon.

A total of 154 strains from 22 species of Bifidobacterium, Peptostreptococcus, Lactobacillus, Ruminococcus, Coprococcus, Eubacterium, and Fusobacterium, which are present in high concentrations in the human colon, were surveyed for their ability to ferment 21 different complex carbohydrates. Plant polysaccharides, including amylose, amylopectin, pectin, polygalacturonate, xylan, laminarin, guar gum, locust bean gum, gum ghatti, gum arabic, and gum tragacanth, were fermented by some strains from Bifidobacterium, Peptostreptococcus, Ruminococcus, and Eubacterium species. Porcine gastric mucin, which was fermented by some strains of Ruminococcus torques and Bifidobacterium bifidum, was the only mucin utilized by any of the strains tested.

Anaerobiosis↗
PubMed1984

Microtus species as new herbivorous laboratory animals: reproduction; bacterial flora and fermentation in the digestive tracts; and nutritional physiology.

In a study of the possible introduction of Japanese field vole (Microtus montebelli ) and Hungarian voles (M. arvalis) as herbivorous experimental animals, the following biological characteristics were investigated: breeding and reproductive performance; bacterial flora and fermentation in the digestive tracts; and nutritional physiology. The animals are polyestrus , show postpartum estrus on the day of parturition, and there is little or no delay in implantation due to lactation, especially in M. arvalis. On examination of vaginal smears, Japanese field vole did not show any definite pattern, whereas most Hungarian voles showed 6- to 18- day cycles. From the esophageal sac of voles fed rations with a high fiber content, cellulolytic bacteria similar to Ruminococcus albus, Ruminococcus flavefaciens , and Bacteroides succinogenes were isolated. More than 1 000 000/g anaerobic bacteria were present in the esophageal sac and the pattern and the types of bacteria resembled those found in the rumen. Gastric fermentation took place in the esophageal sac. The pH and total VFAs were much smaller in the fundic and pyloric regions of the stomach than in the esophageal sac. Acetic and lactic acids were the major fermentation products in the esophageal sac. Following deficiency or lowering of the cellulose decomposing abilities, a decrease of VFAs and an increase in lactic acid production in the esophageal sac were observed. These effects resulted in high glucose, FFA and ketone bodies in the blood, and a higher incidence of glucosuria. Diabetes induced by administrations of drugs such as alloxan, streptozotocin and phloridzin were compared using Microtus and mice. Microtus had low sensitivity to alloxan but high sensitivity to streptozotocin. The influence of monensin on Microtus was also investigated by using diets containing 20 and 80 mg/kg monensin. Diets containing 80 mg/kg monensin led to 50 % mortality in 7 weeks and growth was hindered. Gas production from the esophageal sac contents of voles in the monensin-medicated group was much smaller than that of the non-medicated group. In the monensin group the total VFA concentrations of the esophageal sac contents was decreased.

Animal Nutritional Physiological Phenomena↗
PubMed1991

Enhancing effects of bile salts on the degradation of glycosphingolipids by glycosidases from bacteria of the human fecal flora.

Different concentrations of ionic and non-ionic detergents were examined for optimization of the in vitro degradations of intestinal glycosphingolipids by alpha- and beta-glycosidases from human fecal bacteria. In 5 mM Triton X-100 the enzymes hydrolyzed glycosphingolipids with lactoseries type 1 and 2 chains essentially to lactosylceramide (LacCer). In 5 mM sodium di- and trihydroxy bile salts lactosylceramide was degraded to glycosylceramide (GlcCer) in varying extent by enzymes from all five strains. The minimal bile salt concentrations for optimal 1,4-beta-galactosidase activities varied between 1 and 20 mM, i.e., close to or above the critical micellar concentrations (cmc). Dihydroxy bile salts were the most efficient in promoting conversion of LacCer to GlcCer at concentrations below 10 mM and conjugation with a taurine residue did not markedly lower the GlcCer yield. The optimal detergent concentrations for hydrolyses of the p-nitrophenyl (pnp) glycosides Gal beta 1-pnp and GalNAc alpha 1-pnp were approximately 0.05 mM for Triton X-100 and 0.5 mM for sodium taurodeoxycholate, i.e., clearly below their reported cmc values. Galabiosylceramide, globotria- and globotetraosylceramides, not degraded in the Triton X-100 micelles, were also resistant to hydrolysis using the sodium bile salts as detergents. In contrast, lactotetraosylceramide and isoglobotriaosylceramide were significantly more degraded by enzymes from a Ruminococcus gnavus strain and gangliotetraosylceramide by enzymes from a Bifidobacterium bifidum and a Bifidobacterium infantis strain using bile salt detergents. All strains but R. gnavus released terminal GalNAc from para-Forssman but not from the globotetraosylceramide or Forssman structures using 5 mM sodium deoxycholate as detergent. GM1 desialylation by two Ruminococcus torques strains and the R. gnavus and B. bifidum strains were enhanced under identical conditions. We conclude that the observed effects on glycosphingolipid hydrolyses reflects variations in the micellar presentation of the substrates. In addition, detergents seem to have a direct stimulating effect on the glycosidases, however at concentrations 10-100-times below the ones optimal for glycolipid degradations. These results with optimized bile salt concentrations, further support our previous observations that these five fecal bacterial strains produce enzymes with selected specificities towards glycosphingolipid core chains of the lactoseries type 1 and 2.

Bifidobacterium↗
PubMed1993

Interactions between proteolytic and cellulolytic rumen bacteria during hydrolysis of plant cell wall protein.

During the degradation of the plant cell wall protein of dried alfalfa, interactions may occur between hydrolytic activities of cellulolytic (Ruminococcus albus or Fibrobacter succinogenes) and proteolytic (Prevotella ruminicola or Butyrivibrio fibrisolvens) bacteria. In vitro the hydrolysis of these protein compounds begins after the depolymerization of the cell wall polysaccharides has started. Maximal degradation of cell wall protein of dried alfalfa (37.2%) was obtained with cocultures of Prevotella ruminicola and Ruminococcus albus.

Animals↗
PubMed1991

The hydrolysis of lucerne cell-wall monosaccharide components by monocultures or pair combinations of defined ruminal bacteria.

The defined ruminal bacterial strains Fibrobacter succinogenes S85, Ruminococcus flavefaciens FD1, Ruminococcus albus 7, Butyrivibrio fibrisolvens D1, and Bacteroides ruminicola GA33 were grown, in monocultures or as combinations of pair strains, on isolated lucerne cell-walls (CW) as the sole carbohydrate substrate. Fibrobacter succinogenes S85 was the dominant strain determining extent of CW hydrolysis in all combinations with S85. The hydrolysis of cellulose, xylan, hemicellulose side-sugars, and total CW monosaccharides by pure S85 were: 58.8, 47.3, 66.9 and 57.0%, respectively. The strains combination S85 plus D1 comprised the highest complementary effect, increasing significantly the hydrolysis of cellulose and total CW monosaccharides by 16% and 13%, respectively, above the values obtained by pure S85. This complementation was expressed also in growth pattern of bacteria. The monocultures of FD1, D1 and GA33 had very little hydrolytic effect on lucerne cellulose, but higher effects on xylan and hemicellulose side-sugars. The combinations D1 plus GA33 and 7 plus GA33 were complementary in the hydrolysis of all CW polysaccharides. The combinations FD1 plus D1, FD1 plus GA33, and 7 plus D1 were complementary only with respect to hemicellulose hydrolysis. On the other hand, the cellulolytic combinations S85 plus FD1, S85 plus 7 and FD1 plus 7 demonstrated negative interactions in lucerne CW polysaccharides hydrolysis. Under scanning electron microscopy (SEM), S85 comprised the most dense layer of bacterial cell mass attached to and colonized on CW particles. The cell surface topology of the cellulolytic strains S85, FD1 and 7 attached to CW particles was specified by a coat of characteristic protuberant structures.

Animals↗