Induction of xylan-degrading enzymes inButyrivibrio fibrisolvens

Comparison of the Effects of Essential Oils from Cannabis sativa and Cannabis indica on Selected Bacteria, Rumen Fermentation, and Methane Production-In Vitro Study

This study aimed to evaluate the effects of essential oils (EOs) extracted from Cannabis sativa L. and Cannabis indica Lam. on in vitro ruminal fermentation characteristics, selected rumen microbial populations, and methane production. GC-MS analyses allowed us to identify 89 compounds in both EOs. It was found that E-β-caryophyllene predominated in C. sativa (18.4%) and C. indica (24.1%). An in vitro (Ankom) test was performed to analyse the control and monensin groups, as well as the 50 µL or 100 µL EOs. The samples for volatile fatty acids (VFAs), lactate, and microbiological analysis were taken before incubation and after 6 and 24 h. The application of EOs of C. indica resulted in an increase in the total VFAs of acetate and propionate after 6 h of incubation. The applied EOs had a greater impact on the reduction in methane production after 6 h, but no apparent effect was noted after 24 h. Lower concentrations of C. sativa and C. indica had a more pronounced effect on Lactobacillus spp. and Buryrivibrio spp. than monensin. The presented findings suggest that C. sativa and C. indica supplementation can modify ruminal fermentation, the concentrations of specific volatile fatty acids, and methane production.

Microbiome and fermentation parameters in the rumen of dairy buffalo in response to ingestion associated with a diet supplemented with cysteamine and hemp seed oil

In this study, high-throughput gene amplicon sequencing was used to investigate the effects of 6 treatments [2 levels of hemp seed oil (HSO) × 3 levels of cysteamine (CS)] on bacterial and fungal communities in the rumen of 30 crossbred dairy buffalo. Our results indicate that the total numbers of bacterial and fungal taxa were unaffected regardless of diet (p > 0.05), while the total number of archaea was affected (p < 0.05) by the interaction of HSO and CS. Compared with control treatment, microbial composition of archaea was strongly influenced by CS (p < 0.05), while the addition of HSO, CS or both had a weak effect on fungus and bacteria. In addition, there was a significant increase in the lactic acid content with the addition of HSO, and the addition of CS to the feed caused a significant decrease in the ratio of acetic acid to propionic acid, compared with control treatment (p < 0.05). Correlation analysis showed that Acetobacter was significantly positively correlated with the genera Pichia, Klebsiella and Acinetobacter. pH was found to have a significant effect on the methanogens, and total volatile fatty acids (VFA) had a strong correlation with Butyrivibrio. The strong influence of CS on some methanogens shows that it may have potential in the development of methane reduction interventions.

Comparative Genomics of Rumen Butyrivibrio spp. Uncovers a Continuum of Polysaccharide-Degrading Capabilities

Feeding a global population of 8 billion people and climate change are the primary challenges facing agriculture today. Ruminant livestock are important food-producing animals, and maximizing their productivity requires an understanding of their digestive systems and the roles played by rumen microbes in plant polysaccharide degradation. Members of the genera Butyrivibrio and Pseudobutyrivibrio are a phylogenetically diverse group of bacteria and are commonly found in the rumen, where they are a substantial source of polysaccharide-degrading enzymes for the depolymerization of lignocellulosic material. Our findings have highlighted the immense enzymatic machinery of Butyrivibrio and Pseudobutyrivibrio species for the degradation of plant fiber, suggesting that these bacteria occupy similar niches but apply different degradation strategies in order to coexist in the competitive rumen environment.

Plant polysaccharide breakdown by microbes in the rumen is fundamental to digestion in ruminant livestock. Bacterial species belonging to the rumen genera Butyrivibrio and Pseudobutyrivibrio are important degraders and utilizers of lignocellulosic plant material. These bacteria degrade polysaccharides and ferment the released monosaccharides to yield short-chain fatty acids that are used by the ruminant for growth and the production of meat, milk, and fiber products. Although rumen Butyrivibrio and Pseudobutyrivibrio species are regarded as common rumen inhabitants, their polysaccharide-degrading and carbohydrate-utilizing enzymes are not well understood. In this study, we analyzed the genomes of 40 Butyrivibrio and 6 Pseudobutyrivibrio strains isolated from the plant-adherent fraction of New Zealand dairy cows to explore the polysaccharide-degrading potential of these important rumen bacteria. Comparative genome analyses combined with phylogenetic analysis of their 16S rRNA genes and short-chain fatty acid production patterns provide insight into the genomic diversity and physiology of these bacteria and divide Butyrivibrio into 3 species clusters. Rumen Butyrivibrio bacteria were found to encode a large and diverse spectrum of degradative carbohydrate-active enzymes (CAZymes) and binding proteins. In total, 4,421 glycoside hydrolases (GHs), 1,283 carbohydrate esterases (CEs), 110 polysaccharide lyases (PLs), 3,605 glycosyltransferases (GTs), and 1,706 carbohydrate-binding protein modules (CBM) with predicted activities involved in the depolymerization and transport of the insoluble plant polysaccharides were identified. Butyrivibrio genomes had similar patterns of CAZyme families but varied greatly in the number of genes within each category in the Carbohydrate-Active Enzymes database (CAZy), suggesting some level of functional redundancy. These results suggest that rumen Butyrivibrio species occupy similar niches but apply different degradation strategies to be able to coexist in the rumen.

IMPORTANCE Feeding a global population of 8 billion people and climate change are the primary challenges facing agriculture today. Ruminant livestock are important food-producing animals, and maximizing their productivity requires an understanding of their digestive systems and the roles played by rumen microbes in plant polysaccharide degradation. Members of the genera Butyrivibrio and Pseudobutyrivibrio are a phylogenetically diverse group of bacteria and are commonly found in the rumen, where they are a substantial source of polysaccharide-degrading enzymes for the depolymerization of lignocellulosic material. Our findings have highlighted the immense enzymatic machinery of Butyrivibrio and Pseudobutyrivibrio species for the degradation of plant fiber, suggesting that these bacteria occupy similar niches but apply different degradation strategies in order to coexist in the competitive rumen environment.

Is Pseudobutyrivibrio xylanivorans strain Mz5T suitable as a probiotic? An in vitro study

Rumen bacterium Pseudobutyrivibrio xylanivorans strain Mz5T possessed a potent xylanolytic enzyme system consisting of at least 7 different xylan hydrolases with molar mass 27-145 kDa. Three of them were successfully isolated in active native form. This strain produced butyrate and lactate on different saccharides. cis-9, trans-11-Conjugated linoleic acid was also detected in the culture medium. Bacteriocin-like inhibitory substances of Mz5T were active against some strains of rumen bacteria and against selected Salmonella and E. coli isolates from poultry meat. The strain Mz5T retained viability and xylanolytic activity also under not fully anaerobic conditions; its cells attached to the Caco-2 cells so that its successful association with gut epithelial cells may be expected. These in vitro results confirmed several probiotic traits of the isolate Mz5T and justified further in vivo experiments to test its ability to improve animal health and performance.

Multiple endoxylanases of Butyrivibrio sp

Butyrivibrio sp. Mz 5 with a high xylanolytic activity was isolated. Four major xylanases were detected in the cell-associated fraction using the zymogram technique. The xylanolytic activity was inducible with the oat spelts xylan; two endoxylanases (51 and 145 kDa) were formed constitutively. The bulk of the xylanolytic activity was cell-bound and growth-phase dependent; the maximum activity in the cell-associated fraction was achieved after 16 h of incubation. The highest xylanolytic activity was determined in a medium with 0.5% oat spelts xylan. Under optimum conditions (the highest xylanolytic activity produced), the two cell-bound xylanases (51 and 58 kDa) were isolated by anion exchange chromatography on CIM DEAE 8 tubes attached to a MPLC system, and gel filtration.

Distribution and evolution of the xylanase genes xynA and xynB and their homologues in strains of Butyrivibrio fibrisolvens

The ruminal bacterium Butyrivibrio fibrisolvens is being engineered by the introduction of heterologous xylanase genes in an attempt to improve the utilization of plant material in ruminants. However, relatively little is known about the diversity and distribution of the native xylanase genes in strains of B. fibrisolvens. In order to identify the most appropriate hosts for such modifications, the xylanase genotypes of 28 strains from the three 16S ribosomal DNA (rDNA) subgroups of Butyrivibrio fibrisolvens have been investigated. Only 4 of the 20 strains from 16S rDNA group 2 contained homologues of the strain Bu49 xynA gene. However, these four xynA-containing strains, and two other group 2 strains, contained members of a second xylanase gene family clearly related to xynA (subfamily I). Homologues of xynB, a second previously described xylanase gene from B. fibrisolvens, were identified only in three of the seven group 1 strains and not in the group 2 and 3 strains. However, six of the group 1 strains contained one or more members of the two subfamilies of homologues of xynA. The distribution of genes and the nucleotide sequence relationships between the members of the two xynA subfamilies are consistent with the progenitor of all strains of B. fibrisolvens having contained a xynA subfamily I gene. Since many xylanolytic strains of B. fibrisolvens did not contain members of either of the xynA subfamilies or of the xynB family, at least one additional xylanase gene family remains to be identified in B. fibrisolvens.

Influence of barley and buffer supplements on quantitative aspects of ruminal fiber digestion of cows

Four Jersey cows, fitted with ruminal and duodenal cannulas, were used to assess the specific effects of changes in ruminal pH that were induced by barley addition to a hay diet on ruminal fiber digestion. Cows received successively 100% unchopped cocksfoot hay (diet H), 65% hay and 35% pelleted ground barley (diet HB), and HB plus a continuous intraruminal infusion of bicarbonate salt solution (diet HBB). Cows were limit-fed once daily at 7 kg of DM day-1. The ruminal fractional passage rate of the liquid and hay was respectively estimated from a single administration of Cr-EDTA and Eu labeled on hay fiber. Duodenal fiber flow was estimated both by the double marker method (Yb-acetate/Cr-EDTA) and by multiplying the fractional passage rate of Eu-labeled hay by ruminal pool size. Barley supplement decreased ruminal NDF and ADF digestion compared with diet H, but passage rates of the solid and fluid fractions in the rumen were not affected. The depressive effect of barley supplement on in situ degradability of hay NDF and ADF decreased the degradation rates and increased the 72-h undegradable fraction. Compared with diet HB, ruminal NDF and ADF digestion was improved with buffer supplementation but was less than that of diet H, even though ruminal pH was similar to that of diet H. Passage rates of the fluid and particle fractions were depressed and unaffected, respectively, with buffer addition. Higher in situ degradability of hay with the buffer supplement resulted in an increase in the 72-h undegradable fraction, but the fractional degradation rate was unaffected.