Comparative genomic analysis of Paraclostridium bifermentans in the intestinal microbiome of Hu sheep

The emergence of Paraclostridium bifermentans as a human pathogen has garnered increasing attention. However, due to the challenges associated with isolation, there remains a scarcity of relevant clinical isolates and genomic information. Here, we isolated two P. bifermentans strains PB29 and PB30 from the fecal samples of Hu sheep, characterized the virulence phenotypes, and conducted a comparative genomic analysis to illustrate the evolutionary pathway and distribution of carbohydrate active enzymes (CAZymes). The results indicated that both isolates exhibited substantial phospholipase C and hemolytic activities, while sharing a close phylogenetic relationship. Moreover, strains of P. bifermentans belonging to the same evolutionary lineage as PB29 and PB30 harbor a greater number of virulence factors than strains from other lineages, with the majority originating from the intestine environment. This observation suggests that this lineage has the potential to clonally spread within the gut and evolve into a representative pathogen. Furthermore, P. bifermentans commonly shares mucin degradation carbohydrate hydrolases (GHs) GH2, GH20, and GH73. They also exhibit conserved CAZymes, such as GT4, GT5, CE4, and CE5, which enable them to efficiently metabolize complex carbohydrates and adapt to diverse ecological niches. Overall, these findings offer valuable genomic insights into the potential role of P. bifermentans as an intestinal pathogen.