Bacillus pfraonensis sp. nov., a new strain isolated from a probiotic feed additive with low cytotoxicity and antimicrobial activity.

Probiotic products containing living microorganisms are gaining popularity, increasing the importance of their taxonomic status. A Bacillus-like isolate, 70b, cultured from a probiotic feed additive, was ambiguity in taxonomic assignment and could be a novel member of B. cereus group. The results of colony and cellular morphology, physiological and biochemical analysis mainly including growth performance, carbon source utilization, and rMLST and MLST were not conclusive. Fatty acids profile and molecular genetic analysis especially ANI, DDH, and core genome SNPs-based phylogenetic tree confirmed 70b as one novel species of B. cereus group and proposed as B. pfraonensis sp. nov.. Comparative genomic analysis revealed the genetic differences between 70b and other species of B. cereus group. Pseudomycoicidin was identified in 70b. 70b was active against multidrug-resistant pathogenic strains MRSA. The findings support 70b is a novel species with low cytotoxicity and antimicrobial activity, and provides a better understanding of its unique characteristics and probiotic potential, and exploration of bioactive potential.