Eubacterium sp. strain VPI 12708 has several bile acid-inducible (bai) genes which encode enzymes in the bile acid 7␣-dehydroxylation (7␣DeOH) pathway. Twelve 7␣DeOH-positive intestinal bacterial strains were assayed for 7␣DeOH activity, and 13 strains were tested for hybridization with bai genes. Cholic acid 7␣DeOH activity varied greatly (>100-fold) among these strains. Southern blot experiments showed that DNA prepared from 7 of 13 strains hybridized with at least one of the bai genes from Eubacterium sp. strain VPI 12708.

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An exo-0-1,4-glucanase (Exo A) from Ruminococcus flavefaciens FD-1 was purified to homogeneity and characterized. Enzyme activity was monitored during purification by using the substrate p-nitrophenyl-o-Dcellobioside (NPC). Over 85% of the NPC activity was found to be extracellular once the filter paper was degraded (7 days). Culture supernatant was harvested, and the protein was concentrated by ultrafiltration. The retentate (.300,000 Mr), containing most of the activity against NPC, was then fractionated with a TSK DEAE-5PW column. This yielded a sharp major peak of NPC enzyme activity, followed by a broader, less active area that appeared to contain at least six minor peaks of lower enzymatic activity. Further purification was achieved by chromatography with a hydroxylapatite column. Finally, gel ifitration chromatography yielded a homogeneous enzyme (Exo A) as determined by silver stains of both sodium dodecyl sulfate-and nondenaturing electrophoresis gels. Substrate specificity experiments and the products of cellulose digestion indicate that the enzyme was an exo-,3-1,4-glucanase. Exo Cellulolytic organisms produce several cellulase enzymes which have different specificities and modes of action. At least three types of cellulase enzymes are involved in the degradation of cellulose by fungi (25). Endo-P-1,4-glucanase (EC 3.2.1.4) is produced by all cellulolytic microorganisms and is more commonly referred to as carboxymethylcellulase (CMCase) or C, cellulase. Exo-P-1,4-glucanase (EC 3.2.1.91) is also referred to as C1 cellulase or cellobiohydrolase. ,-1,4-Glucosidase (EC 3.2.1.21) is widely distributed among organisms and is commonly known as cellobiase or P-glucosidase. The most efficient and complete hydrolysis of cellulose is thought to be the result of the combined synergistic action of both endoglucanase and exoglucanase.Two of the most important cellulolytic bacteria in the rumen are Ruminococcus flavefaciens and Ruminococcus albus (2, 11). Typically, these two species ferment cellulose, cellobiose, and xylan. The cellulase systems of both R. flavefaciens and R. albus appear to have many similarities. However, in general, R. flavefaciens degrades crystalline cellulose more efficiently than R. albus (2, 11). This observation suggests that R. flavefaciens possesses exoglucanase activity.Pettipher and Latham (29) investigated the cellulase complex from R. flavefaciens as a crude preparation and concluded that the most active enzymes present in the complex were of the exo-,-1,4-glucanase type. However, the authors did not purify any of the enzymes present or investigate the number and types of cellulolytic enzymes in the different molecular weight complexes. The authors concluded that the major enzyme type was exo-P-1,4-glucanase, based on the products of cellulolytic activity (cellobiose, cellotriose, and a small amount of glucose) and the changes in viscosity versus reducing sugar. However, valid interpretations of cellulase enzyme type cannot be made from data generated * Corresponding author. by a m...

The extracellular endo-1,4-f0-glucanase components of Ruminococcus flavefaciens FD-1 were analyzed by high-performance liquid chromatography (HPLC) by using DEAE ion-exchange, hydroxylapatite, and gel filtration chromatography and polyacrylamide gel electrophoresis (PAGE). Two endo-1,4-0-glucanase peaks were resolved by DEAE-HPLC and termed endoglucanases A and B. Carboxymethyl cellulose (CMC) zymograms were achieved by enzyme separation using nondenaturing PAGE followed by incubation of the gel on top of a CMC-agarose gel. This revealed no less than 13 and 5 endo-1,4-0-glucanase components present in endoglucanases A and B, respectively. Hydroxylapatite chromatography of endoglucanases A and B revealed one activity peak for each preparation, which contained 4 and 5 endo-1,4-0-glucanase components, respectively. Gel filtration chromatography of endoglucanase A following hydroxylapatite chromatography resolved the most active carboxymethylcellulase (CMCase) component from other endo-1,4-,8-glucanase activities. Gel filtration of endoglucanase B following hydroxylapatite chromatography showed one CMCase activity peak.

A gnotobiotic Gallus gallus (chicken) model was developed to study the dynamics of intestinal microflora from hatching to 18 days of age employing metagenomics. Intestinal samples were collected from a local population of feral chickens and administered orally to germfree 3-day-old chicks. Animals were euthanized on days 9 and 18 postinoculation, and intestinal samples were collected and subjected to metagenomic analysis. On day 18, the five most prevalent phyla were Bacteroidetes (43.03 ± 3.19%), Firmicutes (38.51 ± 2.67%), Actinobacteria (6.77 ± 0.7%), Proteobacteria (6.38 ± 0.7%), and Spirochaetes (2.71 ± 0.55%). Principal-coordinate analysis showed that the day 18 variables clustered more closely than the day 9 variables, suggesting that the microbial communities had changed temporally. The Morista-Horn index values ranged from 0.7 to 1, indicating that the communities in the inoculum and in the day 9 and day 18 samples were more similar than dissimilar. The predicted functional profiles of the microbiomes of the inoculum and the day 9 and day 18 samples were also similar (values of 0.98 to 1). These results indicate that the gnotobiotic chicks stably maintained the phylogenetic diversity and predicted metabolic functionality of the inoculum community. IMPORTANCE The domestic chicken is the cornerstone of animal agriculture worldwide, with a flock population exceeding 40 billion birds/year. It serves as an economically valuable source of protein globally. The microbiome of poultry has important effects on chicken growth, feed conversion, immune status, and pathogen resistance. The aim of our research was to develop a gnotobiotic chicken model appropriate for the study chicken gut microbiota function. Our experimental model shows that young germfree chicks are able to colonize diverse sets of gut bacteria. Therefore, besides the use of this model to study mechanisms of gut microbiota interactions in the chicken gut, it could be also used for applied aspects such as determining the safety and efficacy of new probiotic strains derived from chicken gut microbiota.