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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. [ABSTRACT FROM AUTHOR]

Virulence gene profiles of atypical enteropathogenic Escherichia coli (aEPEC) and Shiga toxin-producing E. coli (STEC) from cattle, sheep, and humans were examined to determine the relationship between pathotypes. Shared virulence factors (intimin, EHEC hemolysin, serine protease, and a type II secretion system) were identified, suggesting a dynamic evolutionary relationship between aEPEC and STEC. [ABSTRACT FROM AUTHOR]

Shiga toxin-producing Escherichia coli O84 isolates (n = 22) were examined using culture- and molecularly based methods in order to compare their phenotypic and genotypic characteristics. These analyses directly linked Shiga toxin-producing Escherichia coli O84 isolates from cattle and sheep with human isolates indicating that New Zealand livestock may be a reservoir of infection.

PCR primers were designed to amplify the gene that encodes bovicin 255 from Streptococcus gallolyticus LRC0255 and the bacteriocin genes from Butyrivibrio fibrisolvens strains AR10 and OR79A (bviD and bvi79A) in order to screen for their incidence in rumen and caecal B. fibrisolvens and Streptococcus bovis-like isolates from New Zealand and North American ruminants. None of the B. fibrisolvens-like strains (n=34) isolated from New Zealand or North America had the genes encoding for butyrivibriocins AR10 (bviD) or OR79 (bvi79A). However, seven S. bovis isolates from New Zealand ruminants and three from North American animals had the bovicin 255 gene. Sequence comparison of cloned bovicin 255 PCR products indicated a 92.9-95.7% similarity to that of the corresponding bovicin 255 gene sequence of S. gallolyticus. Four of the New Zealand bovicin 255 positive S. bovis isolates were from the caecal contents of the same sheep and had identical PFGE profiles. Two other S. bovis isolates sharing the same PFGE profile were isolated from a separate animal from the same flock. PFGE analysis of the North American strains indicated that all three were closely related as two of three had identical PFGE profiles with the remaining isolate differing only by a single band position. The 16S rRNA gene sequences of the 10 isolates were at least 99.8% identical to S. bovis. All 10 S. bovis isolates having the gene for bovicin 255 produced bacteriocin activity that inhibited the growth of Peptostreptococcus anaerobius D1 in a deferred antagonism plating (DAP) assay. Certain S. bovis isolates obtained from ruminants have bacteriocin activity associated with a distinct bovicin 255 gene sequence but it appears that bacteriocin production by the rumen anaerobe B. fibrisolvens may be uncommon in strains isolated from cattle and sheep in New Zealand.