Dataset Information

Albusin B, a bacteriocin from the ruminal bacterium Ruminococcus albus 7 that inhibits growth of Ruminococcus flavefaciens.

ABSTRACT: An approximately 32-kDa protein (albusin B) that inhibited growth of Ruminococcus flavefaciens FD-1 was isolated from culture supernatants of Ruminococcus albus 7. Traditional cloning and gene-walking PCR techniques revealed an open reading frame (albB) encoding a protein with a predicted molecular mass of 32,168 Da. A BLAST search revealed two homologs of AlbB from the unfinished genome of R. albus 8 and moderate similarity to LlpA, a recently described 30-kDa bacteriocin from Pseudomonas sp. strain BW11M1.

SUBMITTER: Chen J

PROVIDER: S-EPMC404437 | biostudies-literature | 2004 May

REPOSITORIES: biostudies-literature

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Albusin B, a bacteriocin from the ruminal bacterium Ruminococcus albus 7 that inhibits growth of Ruminococcus flavefaciens.

Chen Junqin J Stevenson David M DM Weimer Paul J PJ

Applied and environmental microbiology 20040501 5

An approximately 32-kDa protein (albusin B) that inhibited growth of Ruminococcus flavefaciens FD-1 was isolated from culture supernatants of Ruminococcus albus 7. Traditional cloning and gene-walking PCR techniques revealed an open reading frame (albB) encoding a protein with a predicted molecular mass of 32,168 Da. A BLAST search revealed two homologs of AlbB from the unfinished genome of R. albus 8 and moderate similarity to LlpA, a recently described 30-kDa bacteriocin from Pseudomonas sp. s ...[more]

PMID: 15128585

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Project description:Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens are the three predominant cellulolytic bacterial species found in the rumen. In vitro studies have shown that these species compete for adherence to, and growth upon, cellulosic biomass. Yet their molecular interactions in vivo have not heretofore been examined. Gnotobiotically raised lambs harboring a 17-h-old immature microbiota devoid of culturable cellulolytic bacteria and methanogens were inoculated first with F. succinogenes S85 and Methanobrevibacter sp. strain 87.7, and 5 months later, the lambs were inoculated with R. albus 8 and R. flavefaciens FD-1. Longitudinal samples were collected and profiled for population dynamics, gene expression, fibrolytic enzyme activity, in sacco fibrolysis, and metabolite profiling. Quantitative PCR, metagenome and metatranscriptome data show that F. succinogenes establishes at high levels initially but is gradually outcompeted following the introduction of the ruminococci. This shift resulted in an increase in carboxymethyl cellulase (CMCase) and xylanase activities but not in greater fibrolysis, suggesting that F. succinogenes and ruminococci deploy different but equally effective means to degrade plant cell walls. Expression profiles showed that F. succinogenes relied upon outer membrane vesicles and a diverse repertoire of CAZymes, while R. albus and R. flavefaciens preferred type IV pili and either CBM37-harboring or cellulosomal carbohydrate-active enzymes (CAZymes), respectively. The changes in cellulolytics also affected the rumen metabolome, including an increase in acetate and butyrate at the expense of propionate. In conclusion, this study provides the first demonstration of in vivo competition between the three predominant cellulolytic bacteria and provides insight on the influence of these ecological interactions on rumen fibrolytic function and metabolomic response.IMPORTANCE Ruminant animals, including cattle and sheep, depend on their rumen microbiota to digest plant biomass and convert it into absorbable energy. Considering that the extent of meat and milk production depends on the efficiency of the microbiota to deconstruct plant cell walls, the functionality of predominant rumen cellulolytic bacteria, Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens, has been extensively studied in vitro to obtain a better knowledge of how they operate to hydrolyze polysaccharides and ultimately find ways to enhance animal production. This study provides the first evidence of in vivo competitions between F. succinogenes and the two Ruminococcus species. It shows that a simple disequilibrium within the cellulolytic community has repercussions on the rumen metabolome and fermentation end products. This finding will have to be considered in the future when determining strategies aiming at directing rumen fermentations for animal production.

Project description:BackgroundThe cellulosome is a multi-enzyme machine, which plays a key role in the breakdown of plant cell walls in many anaerobic cellulose-degrading microorganisms. Ruminococcus flavefaciens FD-1, a major fiber-degrading bacterium present in the gut of herbivores, has the most intricate cellulosomal organization thus far described. Cellulosome complexes are assembled through high-affinity cohesin-dockerin interactions. More than two-hundred dockerin-containing proteins have been identified in the R. flavefaciens genome, yet the reason for the expansion of these crucial cellulosomal components is yet unknown.Methodology/principal findingsWe have explored the full spectrum of 222 dockerin-containing proteins potentially involved in the assembly of cellulosome-like complexes of R. flavefaciens. Bioinformatic analysis of the various dockerin modules showed distinctive conservation patterns within their two Ca(2+)-binding repeats and their flanking regions. Thus, we established the conceptual framework for six major groups of dockerin types, according to their unique sequence features. Within this framework, the modular architecture of the parent proteins, some of which are multi-functional proteins, was evaluated together with their gene expression levels. Specific dockerin types were found to be associated with selected groups of functional components, such as carbohydrate-binding modules, numerous peptidases, and/or carbohydrate-active enzymes. In addition, members of other dockerin groups were linked to structural proteins, e.g., cohesin-containing proteins, belonging to the scaffoldins.Conclusions/significanceThis report profiles the abundance and sequence diversity of the R. flavefaciens FD-1 dockerins, and provides the molecular basis for future understanding of the potential for a wide array of cohesin-dockerin specificities. Conserved differences between dockerins may be reflected in their stability, function or expression within the context of the parent protein, in response to their role in the rumen environment.

Dataset Information

Albusin B, a bacteriocin from the ruminal bacterium Ruminococcus albus 7 that inhibits growth of Ruminococcus flavefaciens.

Publications

Albusin B, a bacteriocin from the ruminal bacterium Ruminococcus albus 7 that inhibits growth of Ruminococcus flavefaciens.

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