Isolation and characterization of the Pseudobutyrivibrio xylanivorans Mz5T xylanase XynT—the first family 11 endoxylanase from rumen Butyrivibrio-related bacteria

Dietary composition and yeast/microalgae combination supplementation modulate the microbial ecosystem in the caecum, colon and faeces of horses

Starchy diets can induce hindgut dysbiosis in horses. The present study evaluated the impact of a yeast (Saccharomyces cerevisiae) and microalgae (Aurantiochytrium limacinum) supplementation on caecal, colonic and faecal microbial ecosystem and on blood inflammatory parameters of horses fed high-fibre or high-starch diets. Six fistulated geldings in a 2 × 2 Latin-square design were alternatively supplemented and received during each period 100 % hay (4 weeks) followed by a 56/44 hay/barley diet (3 weeks). Caecal, colonic and faecal samples were collected 4 h after the morning meal three times per diet, at 5-d intervals, to measure bacterial composition and microbial end products. Blood was simultaneously collected for measuring inflammatory markers. The starchy diet clearly modified the microbial ecosystem in the three digestive segments, with an increase of the amylolytic function and a decrease of the fibrolytic one. However, no effect of the diet was observed on the blood parameters. When horses were supplemented, no significant change was found in lipopolysaccharides, PG-E2, serum amyloid A concentrations and complete blood count neither in cellulose-utilising, starch-utilising and lactate-utilising bacteria concentrations nor in the volatile fatty acids and lactate concentrations and pH. Under supplementation, relative abundance of Family XIII Clostridiales increased in caecum and faeces irrespective of diet and relative abundance of Veillonellaceae was higher during the hay/barley diet in colon and faeces. Most variations of faecal bacterial taxa under supplementation were not observed in the hindgut. However, all variations suggested that supplementation could increase fibrolytic function whatever the diet and limit dysbiosis when the horses' diet changed from high fibre to high starch.

The impact of different levels of cysteine on the plasma metabolomics and intestinal microflora of sows from late pregnancy to lactation

Cysteine (Cys) is a semi-essential amino acid that is synthesized from methionine in mammals and affects their physiological state. This study aimed at investigating the effects of different Cys levels on the birth weight and survival rate of piglets as well as the plasma biochemical parameters, intestinal microbial diversity, and plasma metabolome of sows during late pregnancy. The results showed that 0.4% Cys supplementation increased the birth weight of piglets and decreased the calcium, triglyceride, and bilirubin levels in sows, whereas 0.5% Cys supplementation reduced the gamma-glutamyl transpeptidase levels and increased the serum glucose levels in sows at farrowing. Intestinal microbial analysis demonstrated that 0.4% Cys supplementation increased the diversity of fecal and intestinal microbiota compared with 0.5% Cys supplementation. In addition, plasma metabolomics identified 11 differential metabolites among the 0.4% Cys, 0.5% Cys, and control (basal diet) groups. The serum hypotaurine levels in sows increased by 0.4% and 0.5% Cys supplementation, and the serum acetylcysteine levels increased by 0.5% Cys supplementation; however, the differences in hypotaurine and acetylcysteine levels between the 0.4% and 0.5% Cys groups were not significant. Furthermore, Pearson analysis revealed a positive correlation between the hypotaurine levels and the abundance of Lactobacillus or Pseudobutyrivibrio and a negative correlation between the acetylcysteine levels and the abundance of Ruminococcaceae_UCG-014. Overall, the results indicated that 0.4% Cys supplementation increased the birth weight of piglets, increased the differential metabolites beneficial for combating antioxidative stress in embryos enhancing the intestinal microbial abundance in sows, and increased the diversity of fecal microbiota in sows. Thus, these findings suggest that 0.4% Cys supplementation is highly beneficial for maintaining the health of sows during late pregnancy.

Identification of GH10 xylanases in strains 2 and Mz5 of Pseudobutyrivibrio xylanivorans

Genes encoding glycosyl hydrolase family 11 (GH11) xylanases and xylanases have been identified from Pseudobutyrivibrio xylanivorans. In contrast, little is known about the diversity and distribution of the GH10 xylanase in strains of P. xylanivorans. Xylanase and associated activities of P. xylanivorans have been characterized in detail in the type strain, Mz5. The aim of the present study was to identify GH10 xylanase genes in strains 2 and Mz5 of P. xylanivorans. In addition, we evaluated degradation and utilization of xylan by P. xylanivorans 2 isolated from rumen of Creole goats. After a 12-h culture, P. xylanivorans 2 was able to utilize up to 53% of the total pentose content present in birchwood xylan (BWX) and to utilize up to 62% of a ethanol-acetic acid-soluble fraction prepared from BWX. This is the first report describing the presence of GH10 xylanase-encoding genes in P. xylanivorans. Strain 2 and Mz5 contained xylanases which were related to GH10 xylanase of Butyrivibrio sp. Identifying xylanase-encoding genes and activity of these enzymes are a step toward understanding possible functional role of P. xylanivorans in the rumen ecosystem and contribute to providing an improved choice of enzymes for improving fiber digestion in ruminant animals, agricultural biomass utilization for biofuel production, and other industries.

Isolation of Pseudobutyrivibrio ruminis and Pseudobutyrivibrio xylanivorans from rumen of Creole goats fed native forage diet

We isolated and identified functional groups of bacteria in the rumen of Creole goats involved in ruminal fermentation of native forage shrubs. The functional bacterial groups were evaluated by comparing the total viable, total anaerobic, cellulolytic, hemicellulolytic, and amylolytic bacterial counts in the samples taken from fistulated goats fed native forage diet (Atriplex lampa and Prosopis flexuosa). Alfalfa hay and corn were used as control diet. The roll tubes method increased the possibility of isolating and 16S rDNA gene sequencing allowed definitive identification of bacterial species involved in the ruminal fermentation. The starch and fiber contents of the diets influenced the number of total anaerobic bacteria and fibrolytic and amylolytic functional groups. Pseudobutyrivibrio ruminis and Pseudobutyrivibrio xylanivorans were the main species isolated and identified. The identification of bacterial strains involved in the rumen fermentation helps to explain the ability of these animals to digest fiber plant cell wall contained in native forage species.

GH11 xylanases: Structure/function/properties relationships and applications

For technical, environmental and economical reasons, industrial demands for process-fitted enzymes have evolved drastically in the last decade. Therefore, continuous efforts are made in order to get insights into enzyme structure/function relationships to create improved biocatalysts. Xylanases are hemicellulolytic enzymes, which are responsible for the degradation of the heteroxylans constituting the lignocellulosic plant cell wall. Due to their variety, xylanases have been classified in glycoside hydrolase families GH5, GH8, GH10, GH11, GH30 and GH43 in the CAZy database. In this review, we focus on GH11 family, which is one of the best characterized GH families with bacterial and fungal members considered as true xylanases compared to the other families because of their high substrate specificity. Based on an exhaustive analysis of the sequences and 3D structures available so far, in relation with biochemical properties, we assess biochemical aspects of GH11 xylanases: structure, catalytic machinery, focus on their "thumb" loop of major importance in catalytic efficiency and substrate selectivity, inhibition, stability to pH and temperature. GH11 xylanases have for a long time been used as biotechnological tools in various industrial applications and represent in addition promising candidates for future other uses.

Xyn11A, a multidomain multicatalytic enzyme fromPseudobutyrivibrio xylanivorans Mz5T

The rumen bacterium Pseudobutyrivibrio xylanivorans Mz5T has a potent xylanolytic enzyme system. A small native peptide (approximately 30-kDa, designated Xyn11A) from the bacterium was first isolated and characterized by Edman degradation. The gene coding for Xyn11A was identified using PCR amplification with consensus primers. It was then fully sequenced to reveal an open reading frame of 1809 bp. The predicted N-terminal domain exhibited xylanolytic activity and was classed to the family 11 of glycosyl hydrolases; it is followed by a region with homology to a family 6 cellulose binding module. The C-terminal domain codes for a putative NodB-like polysaccharide deacetylase which is predicted to be an acetyl esterase implicated in debranching activity in the xylan backbone. As similar domain organization was also found in several other xylanases from a diverse range of bacteria, a common ancestor of such a xylanase is considered to be present and spread, possibly by horizontal gene transfer, to other microorganisms from different ecological niches.