Fibrisolvens D1 Research Articles

Sharpea azabuensis: a ruminal bacterium that produces trans-11 intermediates from linoleic and linolenic acid.

To investigate the metabolism of 18:2n-6 and 18:3n-3 by pure cultures of Sharpea azabuensis, two different strains (RL 1 and ST18) were each incubated in the presence of 40 µg ml-1 18:2n-6 or 18:3n-3. Pure cultures of Butyrivibriofibrisolvens D1 and Butyrivibrio proteoclasticus P18 were included as control treatments. Similar to the metabolism of B. fibrisolvens, both S. azabuensis strains converted 18:2n-6 or 18:3n-3 to cis-9, trans-11 CLA or cis-9, trans-11, cis-15 CLnA, after which it was further reduced to trans-11 18:1 or trans-11, cis-15 18:2, respectively. B. proteoclasticus additionally reduced trans-11 18:1 to 18:0. Trans-11, cis-15 18:2 was also further metabolized by B. proteoclasticus, although trans-11 18:1 did not accumulate, and only minor amounts of 18:0 were formed. The time frame of 18:2n-6 and 18:3n-3 biohydrogenation by S. azabuensis was comparable with B. fibrisolvens, indicating that S. azabuensis and B. fibrisolvens might be alternative biohydrogenators of 18:2n-6 and 18:3n-3 in the rumen.

Biohydrogenation of 22:6n-3 by Butyrivibrio proteoclasticus P18.

BackgroundRumen microbes metabolize 22:6n-3. However, pathways of 22:6n-3 biohydrogenation and ruminal microbes involved in this process are not known. In this study, we examine the ability of the well-known rumen biohydrogenating bacteria, Butyrivibrio fibrisolvens D1 and Butyrivibrio proteoclasticus P18, to hydrogenate 22:6n-3.ResultsButyrivibrio fibrisolvens D1 failed to hydrogenate 22:6n-3 (0.5 to 32 μg/mL) in growth medium containing autoclaved ruminal fluid that either had or had not been centrifuged. Growth of B. fibrisolvens was delayed at the higher 22:6n-3 concentrations; however, total volatile fatty acid production was not affected. Butyrivibrio proteoclasticus P18 hydrogenated 22:6n-3 in growth medium containing autoclaved ruminal fluid that either had or had not been centrifuged. Biohydrogenation only started when volatile fatty acid production or growth of B. proteoclasticus P18 had been initiated, which might suggest that growth or metabolic activity is a prerequisite for the metabolism of 22:6n-3. The amount of 22:6n-3 hydrogenated was quantitatively recovered in several intermediate products eluting on the gas chromatogram between 22:6n-3 and 22:0. Formation of neither 22:0 nor 22:6 conjugated fatty acids was observed during 22:6n-3 metabolism. Extensive metabolism was observed at lower initial concentrations of 22:6n-3 (5, 10 and 20 μg/mL) whereas increasing concentrations of 22:6n-3 (40 and 80 μg/mL) inhibited its metabolism. Stearic acid formation (18:0) from 18:2n-6 by B. proteoclasticus P18 was retarded, but not completely inhibited, in the presence of 22:6n-3 and this effect was dependent on 22:6n-3 concentration.ConclusionsFor the first time, our study identified ruminal bacteria with the ability to hydrogenate 22:6n-3. The gradual appearance of intermediates indicates that biohydrogenation of 22:6n-3 by B. proteoclasticus P18 occurs by pathways of isomerization and hydrogenation resulting in a variety of unsaturated 22 carbon fatty acids. During the simultaneous presence of 18:2n-6 and 22:6n-3, B. proteoclasticus P18 initiated 22:6n-3 metabolism before converting 18:1 isomers into 18:0.

Antimicrobial activity of Brazilian propolis extracts against rumen bacteria in vitro

The antimicrobial activity of three Brazilian propolis extracts was evaluated on bacterial strains representing major rumen functional groups. The extracts were prepared using different concentrations of propolis and alcohol, resulting in different phenolic compositions. The propolis extracts inhibited the growth of Fibrobacter succinogenes S85, Ruminococcus flavefaciens FD-1, Ruminococcus albus 7, Butyrivibrio fibrisolvens D1, Prevotella albensis M384, Peptostreptococcus sp. D1, Clostridium aminophilum F and Streptococcus bovis Pearl11, while R. albus 20, Prevotella bryantii B₁4 and Ruminobacter amylophilus H18 were resistant to all the extracts. The inhibited strains showed also different sensitivity to propolis; the hyper-ammonia-producing bacteria (C. aminophilum F and Peptostreptococcus sp. D1) being the most sensitive. Inhibition of hyper-ammonia-producing bacteria by propolis would be beneficial to the animal. The extract containing the lowest amount of phenolic compounds (LLOS C3) showed the lowest antimicrobial activity against all the bacteria. The major phenolic compounds identified in the propolis extracts (naringenin, chrysin, caffeic acid, p-coumaric acid and Artepillin C) were also evaluated on four sensitive strains. Only naringenin showed inhibitory effect against all strains, suggesting that naringenin is one of the components participating to the antibacterial activity of propolis.

Dietary supplementation of ruminant diets with an Aspergillus oryzae α-amylase

Research in the area of dietary enzyme supplements for ruminant diets has primarily focused on fibrolytic enzymes, while activities involved in the process of starch digestion have been largely ignored. Since starch represents a major component in diets fed to highly productive cattle, the use of enzymatic dietary supplements to manipulate starch digestion in the rumen may allow improved productivity. This review discusses current information on dietary supplementation of calf, dairy and beef cattle diets with an Aspergillus oryzae extract containing α-amylase activity. During starch hydrolysis, α-amylase randomly cleaves starch polymers to low molecular weight oligosaccharides and eventually produces maltotriose and maltose from amylose and α-limit dextrins, maltose and glucose from amylopectin. Through its hydrolytic action, supplemental α-amylase hypothetically increases the availability of starch hydrolysis products in the rumen consequently altering the ruminal fermentation process. Data from studies employing lactating dairy cows, steers or rumen-simulating continuous cultures suggest that supplemental α-amylase did not increase ruminal starch digestion but consistently increased butyrate and reduced propionate molar proportions in the rumen. The increase in ruminal butyrate was also reflected in higher blood β-hydroxybutyrate concentrations in both transition and lactating dairy cows. In addition, supplemental α-amylase enhanced ruminal epithelium growth in dairy calves, a tissue that preferentially uses butyrate as an energy source. Experiments with pure cultures of ruminal bacteria showed that supplemental α-amylase supported rapid growth of bacteria that cannot grow, or grow slowly, on starch such as Butyrivibrio fibrisolvens D1, Selenomonas ruminantium GA192 or Megasphaera elsdenii T81. In contrast, bacteria that grow rapidly on starch, such as Streptococcus bovis S1 or Butyrivibrio fibrisolvens 49, did not benefit from α-amylase supplementation. Animal performance studies showed higher weight gain, and longissimus muscle area, in finishing beef cattle fed supplemental α-amylase. Weight gain improvements were primarily mediated through increased dry matter intake, which may be a consequence of reduced ruminal propionate molar proportions reported in other studies. In lactating dairy cattle, supplemental α-amylase increased milk yield, reduced milk fat proportion without reducing milk fat yield and tended to improve milk protein yield when data from 45 commercial herds (approximately 8150 cows) were examined. Currently available data on effects of the Aspergillus oryzae α-amylase described here suggest that this enzyme supplement may improve animal productivity by modifying ruminal starch digestion without necessarily increasing starch digestion in the rumen.

Use of ratio of digested xylan to digested cellulose (X/C) as an index of fiber digestion in plant cell-wall material by ruminal microorganisms

Traits in digestion of plant cell-wall components of timothy ( Phleum pratense) hay were studied in pure cultures of ruminal fibrolytic microorganisms and in sacco. Four strains of rumen bacteria, Butyrivibrio fibrisolvens D1 (ATCC19171), Fibrobacter succinogenes S85 (ATCC19169), Prevotella ruminicola subsp. brevis 7-31, and Ruminococcus albus 7, and four strains of anaerobic fungi, Neocallimastix frontalis MCH3, Piromyces communis 93-3, Piromyces sp. P1 and polycentric fungus KP1, were used in this experiment. Each microorganism was inoculated on ground timothy hay (20 g l −1) in an anaerobic medium and incubated at 39°C. Dry matter loss of timothy hay and digested xylan to digested cellulose (X/C) ration of the substrate during incubation were determined. The X/C ratios in the cultures of Pre. ruminicola and B. fibrisolvens were greater than 0.5. Those of R. albus, Pir. communis, Piromyces sp. P1 and N. frontalis were between 0.3 and 0.5. Those of F. succinogenes and polycentric fungus KP1 were lower than 0.3. The X/C ratios observed in sacco were around 0.2 and close to those of F. succinogenes. The similarity of the digested X/C ratios between F. succinogenes and in sacco measurements suggests that F. succinogenes plays a predominant role in fiber digestion in the rumen.

Digestion of cell-wall monosaccharides of ryegrass and alfalfa hays by the ruminal bacteria Fibrobacter succinogenes and Butyrivibrio fibrisolvens.

The ruminal bacteria Fibrobacter succinogenes strains S85 and BL2 were grown in monocultures or in coculture with strain D1 of Butyrivibrio fibrisolvens, and the solubilization of ryegrass and alfalfa cell walls (CW) and digestion of CW monosaccharides were measured. Fibrobacter succinogenes monocultures and cocultures with B. fibrisolvens D1 degraded 58-69% of ryegrass CW, solubilizing 67-78% of CW glucose, 65-71% of CW xylose, 69-75% of hemicellulose, and 68-77% of total CW monosaccharides. When grown on alfalfa CW, those cultures degraded 28-39% of alfalfa CW, solubilizing 42-58% of CW glucose, 30-36% of CW xylose, and 37-45% of hemicellulose. With respect to both substrates, F. succinogenes strains solubilized CW carbohydrates better than did B. fibrisolvens D1. Complementary interaction between B. fibrisolvens D1 and the F. succinogenes strains was identified with respect to the utilization of some solubilized carbohydrates, but not with respect to the extent of CW solubilization, which was determined mainly by the F. succinogenes strains. For both substrates, utilization of cellulose by F. succinogenes monocultures was high (96-98%), whereas that of hemicellulose was lower (24-26% in ryegrass and 49-50% in alfalfa). Under scanning electron microscopy, F. succinogenes bacterial cells attached to and colonized on CW particles were characterized by the appearance of protuberant surface structures that we have identified as "polycellulosome complexes."

Digestion of structural polysaccharides of Panicum and vetch hays by the rumen bacterial strains Fibrobacter succinogenes BL2 and Butyrivibrio fibrisolvens D1

The rumen bacterial strains Fibrobacter succinogenes BL2 and Butyrivibrio fibrisolvens D1, were grown in monocultures and pair combination on cell walls (CW) of two tropical hays: Panicum (grass) and vetch (legume), and their ability to solubilize and utilize CW structural carbohydrate was determined. With respect to both substrates, F. succinogenes BL2 was a better solubilizer of CW carbohydrate than B. fibrisolvens D1. However, the solubilization of Panicum constituents by any bacterial monoculture and co-culture was higher than that of vetch. Complementary interaction between B. fibrisolvens D1 and F. succinogenes BL2 was identified only with respect to carbohydrate utilization, but not with the extent of CW solubilization, which was determined mainly by the F. succinogenes strain. In both substrates, utilization of solubilized cellulose by BL2 monocultures was high (86.4–97.5%), whereas that of solubilized xylan and hemicellulose was much lower (35.2–41.6%). Under scanning electron microscopy visualization, the BL2 bacterial cell mass attached to and colonized on CW particles was characterized by the appearance of protuberant structures known as “polycellulosome complexes” on their surface topology.

The degradation and utilization of structural polysaccharides of sorghum straw by defined ruminal bacteria

Cell wall (CW) preparations of untreated sorghum straw (SORG) and sulfur dioxide-treated SORG (T-SORG) were used as substrates for the solubilization and utilization of CW carbohydrates by pure cultures or pair-combinations of defined rumen bacterial strains. Ruminococcus flavefaciens FD1 and R. albus 7 monocultures and cocultures with Butyrivibrio fibrisolvens D1 had very little solubilizing effect on SORG and even less on T-SORG CW. Fibrobacter succinogenes S85 was the best solubilizer of SORG CW components. The T-SORG CW was composed of fewer hemicellulose components and more cellulose and total CW polysaccharides than the SORG CW. Consequently, F. succinogenes S85 and BL2 monocultures and their cocultures with D1 degraded T-SORG CW polysaccharides by 21–33% units better than those of SORG CW, solubilizing 61–66% of T-SORG CW-glucose, 58–62% of CW-xylose, 58–63% of hemicellulose and 61–65% of total T-SORG structural polysaccharides. Complementary action between B. fibrisolvens D1 and the F. succinogenes strains was identified with respect to coculture growth and carbohydrate utilization, but not with respect to the extent of CW solubilization which was determined mainly by the F. succinogenes strains during 120 h of coculture incubation. In both CW substrates, utilization of solubilized cellulose by F. succinogenes S85 and BL2 monocultures was higher than that of CW-xylose and hemicellulose, being 97–98%, 53–69% and 54–75%, respectively. Under scanning electron microscopic visualization SORG CW particles were less colonized by attached bacterial cells than T-SORG. In both substrates attached F. succinogenes cells were characterized by the appearance of protuberant structures on their surface topology.

Untreated and delignified cotton stalks as model substrates for degradation and utilization of cell-wall monosaccharide components by defined ruminal cellulolytic bacteria

Pure cultures of the defined ruminal bacterial strains Fibrobacter succinogenes S85 and BL2, Ruminococcus flavefaciens FD1, Ruminococcus albus 7 and Butyrivibrio fibrisolvens D1, and the pair combinations of strains S85 + D1, BL2 + D1, FD1 + D1 and 7 + D1, were grown on isolated cell walls (CW) of untreated cotton stalks (CS) or ozone-treated CS (OCS) as the sole added carbohydrate substrate. F. succinogenes S85 was the best CW hydrolyzer of CS, solubilizing 27·9% of CW-glucose polymers, 21·9% of xylan, 24·8% of hemicellulose and 26·9% of total CS-CW polysaccharides. The Ruminococci monocultures and cocultures had very little hydrolytic effect on CS but somewhat better hydrolytic effect on OCS-CW. Since OCS-CW contained less lignin and hemicellulose components and more cellulose and total CW polysaccharides than CS-CW all bacterial cultures and cocultures degraded OCS-CW components better than CS-CW polysaccharides. S85 was the best hydrolyzer of OCS residual CW, solubilizing 52·8% of CW-glucose, 51·2% xylan, 51·5% hemicellulose and 52·6% of total OCS-CW monosaccharides. There was complementary action between B. fibrosolvens D1 and the F. succinogenes strains S85 and BL2 with respect to coculture growth and carbohydrate utilization, but not to the extent of CW hydrolysis, which was determined mainly by the F. succinogenes strains during the 120 h of coculture incubations. Utilization of solubilized cellulose, xylan, hemicellulose sugars and total carbohydrates by S85 monoculture was 94·4%, 80·3%, 61·4% and 84·1%, respectively, with respect to CS components, and 96·7%, 64·8%, 62·1% and 89·6% with respect to OCS-CW carbohydrates. Under scanning electron microscopy (SEM) visualization, S85 formed the most dense layer of bacterial cell mass attached to, and colonized on, OCS-CW stems. CW particles of CS were less crowded with attached bacteria. The cell-surface topology of S85 cells attached to CW particles was specified by a coat of characteristic protuberant structures.

The degradation and utilization of wheat-straw cell-wall monosaccharide components by defined ruminal cellulolytic bacteria

Cell walls (CW) of untreated wheat straw and sulphur-dioxide (SO2)-treated wheat straw were used as model substrates for the hydrolysis and utilization of CW carbohydrates by pure cultures or pair-combinations of defined rumen bacterial strains. Fibrobacter succinogenes S85 and BL2 strains and their co-cultures with D1 were the best degraders of CW among ruminal cultures, solubilizing 37.2–39.6% of CW carbohydrates of untreated straw and 62.2–74.5% of SO2-treated straw. Complementary action between Butyrivibrio fibrisolvens D1 and the F. succinogenes strains was identified with respect to co-culture growth and carbohydrate utilization. However, the extent of CW solubilization was determined mainly by the F. succinogenes strains. In both substrates, utilization of solubilized cellulose by F. succinogenes S85 and BL2 monocultures was higher than that of xylan and hemicellulose: 96.5–98.3%, 34.4–40.5% and 33.5–36.2%, respectively. Under scanning electron microscopy visualization, S85 and BL2 cells of the co-cultures comprised the most dense layer of bacterial cell mass attached to and colonized on straw stems and leaves, whereas D1 cells were always nearby. Stems and leaves of the untreated straw were less crowded by attached bacteria than that of the SO2-treated straw. In both materials, the cell surface topography of S85 and BL2 bacteria attached to CW particles was specified by a coat of characteristic protuberant structures, “polycellulosome complexes”.

Conjugal transfer of Tn916, Tn916 delta E, and pAM beta 1 from Enterococcus faecalis to Butyrivibrio fibrisolvens strains.

Anaerobic filter matings of Butyrivibrio fibrisolvens H17c, CF3, D1, or GS113, representing different DNA relatedness groups, were done with Enterococcus faecalis CG110, which contains chromosomally inserted Tn916. Tetracycline-resistant transconjugants were obtained with each mating pair at average frequencies of 4.4 x 10(-6) (per recipient) and 5.2 x 10(-6) (per donor). The transfer frequencies of Tn916 into B. fibrisolvens varied 5- to 10-fold with mating time, strain, and growth stage. By using Southern hybridization with pAM120 as the probe, Tn916 was shown to insert at one or more separate chromosomal sites for each strain of B. fibrisolvens. Retransfer of Tn916 from B. fibrisolvens H17c or CF3 to E. faecalis OG1-X or JH 2-2 or to B. fibrisolvens D1 or GS113 could not be shown. Matings of E. faecalis RH110, which contains chromosomally inserted Tn916 delta E, with B. fibrisolvens 49, H17c, D1, CF3, GS113, or VV-1 resulted in erythromycin-resistant transconjugants at average frequencies of 5.3 x 10(-7) (per recipient) and 2.5 x 10(-7) (per donor). Tn916 delta E was shown by Southern hybridization with pAM120 to insert at one or more sites in the chromosome of each strain. B. fibrisolvens H17c was anaerobically filter mated with E. faecalis JH 2-SS, which contains pAM beta 1. Erythromycin-resistant transconjugants were obtained at frequencies of 2 x 10(-5) (per recipient) and 6 x 10(-5) (per donor). The presence of pAM beta 1 in these transconjugants could not be shown by agarose gel electrophoresis of plasmid minilysates but could be shown by Southern hybridization analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Effects of chetomin on growth and acidic fermentation products of rumen bacteria.

Chetomin, an antibiotic metabolite of Chaetomium spp., was tested in the form of its tetrathiol derivative for its effects on growth and carbohydrate metabolism by five strains of functionally important rumen bacteria. The compound was bacteriostatic for the strains tested and Gram-positive bacteria were more sensitive to inhibition than Gram-negative bacteria. In an anaerobic broth dilution assay using a medium lacking rumen fluid, the minimum inhibitory concentration (MIC) of chetomin which completely inhibited growth of Butyrivibrio fibrisolvens D1 for 18 h at 39 degrees C was 40 micrograms X mL-1. The MICs determined under the same conditions for Megasphaera elsdenii B159, Selenomonas ruminantium GA192, and Succinivibrio dextrinosolvens 24 were 160, 600, and 60 micrograms X mL-1, respectively. The MIC for cellulose hydrolysis by Ruminococcus albus 7 was 20 micrograms X mL-1. Chetomin at concentrations below the MIC appeared to inhibit the separation and division of cells in cultures of B. fibrisolvens D1. Chetomin consistently stimulated acetate production from glucose by B. fibrisolvens D1, M. elsdenii B159, and S. ruminantium GA192 at the expense of compounds which comprised major soluble end products of fermentation in cultures lacking chetomin.

Enzymology of butyrate formation by Butyrivibrio fibrisolvens.

Butyrivibrio fibrisolvens is a major butyrate-forming species in the bovine and ovine rumen. The enzymology of butyrate formation from pyruvate was investigated in cell-free extracts of B. fibrisolvens D1. Pyruvate owas oxidized to acetylcoenzyme A (CoA) in the presence of CoA.SH and benzyl viologen or flavin nucleotides. The bacterium uses thiolase, beta-hydroxybutyryl-CoA dehydrogenase, crotonase, and crotonyl-CoA reductase to form butyryl-CoA from acetyl-CoA. Reduction of acetoacetyl-CoA to beta-hydroxybutyryl-CoA was faster with NADH than with NADPH. Crotonyl-CoA was reduced to butyryl-CoA by NADH, but not by NADPH, only in the presence of flavin nucleotides. Reduction of flavin nucleotides by NADH was much slower than the flavin-dependent reduction of crotonyl-CoA. This indicates that flavoproteins rather than free flavin participated in the reduction of crotonyl-CoA. Butyryl-CoA was converted to butyrate by phosphate butyryl transferase and butyrate kinase.

Effect of acetohydroxamic acid on growth and volatile fatty acid production by rumen bacteria.

Six strains of anaerobic rumen bacteria were grown in a rumen fluid medium containing different concentrations of the urease inhibitor, acetohydroxamic acid. Bacteroides succinogenes S85 failed to grow in the presence of 1 × 10−2 M acetohydroxamic acid whereas growth by Selenomonas ruminantium GA192 was not affected when the initial concentration was 5 × 10−2 M. In cultures of the remaining strains, acetohydroxamic acid extended the lag phase without changing the growth rate in the log phase. The order of decreasing overall sensitivity to acetohydroxamic acid by the strains in terms of growth was Bacteroides succinogenes S85 [Formula: see text]Bacteroides ruminicola 23 > Butyrivibrio fibrisolvens D1 ≥ Butyrivibrio sp. C3 > Megasphaera (Peptostreptococcus) elsdenii B159 > Selenomonas ruminantium GA192. Washed cell suspensions of Butyrivibrio fibrisolvens D1, Megasphaera elsdenii B159, and Selenomonas ruminantium GA192, but of none of the other strains were capable of degrading acetohydroxamic acid. In the presence of 5 × 10−3 M acetohydroxamic acid, the extent of glucose, starch, and xylan fermentation by the strains was modified. The amounts and molar proportions of volatile fatty acids produced from these substrates were also changed. In Bacteroides ruminicola 23, the presence of acetohydroxamic acid resulted in an 89% reduction in glucose fermentation and a shift in volatile fatty acid production from propionate to acetate. Butyrivibrio fibrisolvens D1 and Butyrivibrio sp. C3 fermented more glucose, but less xylan, when acetohydroxamic acid was present; with glucose as substrate, volatile fatty acid production shifted markedly from n-butyrate to propionate. The results support the conclusion drawn from previous studies with the mixed rumen microbiota, that the potential effect of the compound upon rumen microbial activities in vivo is not limited to inhibition of urease activity.

Isolation and identification of rumen bacteria capable of anaerobic rutin degradation.

Fifteen strains of bacteria capable of degrading rutin anaerobically were isolated from bovine rumen contents and identified by morphological and biochemical evidence as strains of Butyrivibrio sp. Three cultures from a laboratory collection of 53 strains of rumen bacteria also used rutin anaerobically. Two, Butyrivibrio fibrisolvens D1 and Selenomonas ruminantium GA192, cleaved the glycosidic bond of rutin and fermented the sugar but did not degrade the insoluble aglycone produced; the third strain, Peptostreptococcus sp. B178, degraded the substrate to soluble products. Butyrivibrio sp. C3 degraded rutin, quercitrin, and naringin to water-soluble products, showing that the organism cleaved the heterocyclic ring of these compounds. Butyrivibrio sp. C3 fermented the sugar moiety of hesperidin but did not cleave the heterocyclic ring. It did not attack quercetin, taxifolin, protocatechuic acid, or phloroglucinol. In a medium containing rumen fluid, Butyrivibrio sp. C3 degraded rutin more than twice as fast as it did in a medium containing enzymatic casein hydrolyzate, volatile fatty acids, yeast extract, and hemin in place of rumen fluid.The observations reported in this paper are believed to represent the first recorded demonstration of degradation of the heterocyclic ring structure of rutin and other bioflavonoids in pure cultures of anaerobic bacteria.