Search

The distribution of enterohemolysin subtypes, a plasmid-encoded toxin, among Escherichia coli isolates from various human and animal sources is assessed. No apparent difference that can indicate specific roles for enterohemolysin in the separate hosts is found.

The first screening of dairy cows, sheep and deer fed fresh forage for the presence of ammonia-hyperproducing bacteria (HAP) is reported. Five HAP rumen bacteria were isolated and characterized, namely, C2, D1, D4, D5 and S1. 16s ribosomal DNA sequences were tested and analyzed, finding that all isolates were monensin sensitive. D1 and S1 were found to belong to the genus Peptostreptococcus, D4 and D5 to the family Bacteroidaceae, and C2 was found to be very similar to an unidentified species from the genus Eubacterium.

Analyses of carboxymethyl cellulose (CMC) Trypticase glucose yeast plates stained with Congo red established heterologous expression of the Clostridium cellulovorans engB gene by Clostridium acetobutylicum BKW-1 at regions of hydrolysis. A specific activity toward CMC that is fourfold greater than that in C. acetobutylicum ATCC 824 is evident during the extracellular cellulose preparation from C. acetobutylicum BKW-1.

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. The identified shared virulence factors such as intimin, EHEC hemolysin, serine protease, and a type II secretion system indicated a dynamic evolutionary relationship between aEPEC and STEC.

Atypical enteropathogenic Escherichia coli (aEPEC) and Shiga toxin-producing E. coli (STEC) were characterized to determine the prevalence and sequence of espP which encodes a serine protease. The shared espP sequence types observed between the two E. coli pathotypes provide better insight into the evolution of aEPEC and STEC.

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]

Rumen bacterial species belonging to the genus Butyrivibrio are important degraders of plant polysaccharides, particularly hemicelluloses (arabinoxylans) and pectin. Currently, four species are recognized which have very similar substrate utilization profiles, but little is known about how these microorganisms are able to co-exist in the rumen. To investigate this question, Butyrivibrio hungatei MB2003 and Butyrivibrio proteoclasticus B316T were grown alone or in co-culture on xylan or pectin, and their growth, release of sugars, fermentation end products and transcriptomes were examined. In mono-cultures, B316T was able to grow well on xylan and pectin, while MB2003 was unable to utilize either of these insoluble substrates to support significant growth. Co-cultures of B316T grown with MB2003 revealed that MB2003 showed almost equivalent growth to B316T when either xylan or pectin were supplied as substrates. The effect of co-culture on the transcriptomes of B316T and MB2003 was assessed; B316T transcription was largely unaffected by the presence of MB2003, but MB2003 expressed a wide range of genes encoding carbohydrate degradation, central metabolism, oligosaccharide transport and substrate assimilation in order to compete with B316T for the released sugars. These results suggest that B316T has a role as an initiator of primary solubilization of xylan and pectin, while MB2003 competes effectively for the released soluble sugars to enable its growth and maintenance in the rumen. [ABSTRACT FROM AUTHOR]

Cladosporium and Epicoccum are cosmopolitan fungi of the class Dothideomycetes with few cultured and genomic representatives. Here, we report draft reference genome sequences of Epicoccum sp. F181 (GenBank accession number JAJSLS01), Cladosporium sp. F165 (JAJSLR01), and F190 (JAJSLT01) isolated from recycling and waste management facilities in New Zealand.