Genome-wide characterization and comparative analysis of Bacillus paranthracis MBBL1 reveals genomic plasticity features.

Bacillus paranthracis is a member of the Bacillus cereus group with close phylogenetic proximity to pathogenic species, yet its genomic diversity and pathogenic potential remain poorly understood. In this study, we present a comprehensive whole-genome analysis of B. paranthracis strain MBBL1, an environmental isolate, to explore its genomic architecture, evolutionary relationships, and potential virulence traits. Comparative genomic and pangenome analyses revealed that MBBL1 clusters closely with other B. paranthracis strains while maintaining measurable genomic similarity to B. cereus and B. anthracis. Notably, the genome lacks plasmids and known serotype markers, distinguishing it from many pathogenic members of the group. Despite this, MBBL1 harbors multiple chromosomally encoded virulence-associated genes, mobile genetic elements, and genomic islands, indicating considerable genomic plasticity. The presence of an active Type I CRISPR-Cas system may contribute to genome stability and the absence of plasmids. Pathogenicity prediction suggests a low but detectable potential for human pathogenicity. Collectively, these findings highlight the importance of environmental Bacillus strains as reservoirs of hidden virulence traits and provide a valuable genomic framework for future functional and risk assessment studies.