Diversity within the species Clostridium butyricum: pan-genome, phylogeny, prophage, carbohydrate utilization, and antibiotic resistance.

ABSTRACT

AIMS: Clostridium butyricum has been recognized as a strong candidate for the "next generation of probiotics" due to its beneficial roles on humans. Owing to our current understanding of this species is limited, it is imperative to unveil the genetic variety and biological properties of C. butyricum on sufficient strains. METHODS AND RESULTS: We isolated 53 C. butyricum strains and collected 25 publicly available genomes to comprehensively assess the genomic and phenotypic diversity of this species. Average nucleotide identity and phylogeny suggested that multiple C. butyricum strains might share the same niche. Clostridium butyricum genomes were replete with prophage elements, but the CRISPR-positive strain efficiently inhibited prophage integration. Clostridium butyricum utilizes cellulose, alginate, and soluble starch universally, and shows general resistance to aminoglycoside antibiotics. CONCLUSIONS: Clostridium butyricum exhibited a broad genetic diversity from the extraordinarily open pan-genome, extremely convergent core genome, and ubiquitous prophages. In carbohydrate utilization and antibiotic resistance, partial genotypes have a certain guiding significance for phenotypes.