A novel soil Bacillus strain GB_SG_008: isolation, characterization, and anticancer potential of an intracellular protein fraction inducing apoptosis and modulating cancer marker proteins.

Cancer continues to pose a significant global health challenge, with traditional therapies often limited by toxicity and resistance, underscoring the need for alternative strategies. Microorganisms and their bioactive products have emerged as valuable sources of novel anticancer agents. In this study, we isolated a wild-type bacterium from soil and performed a comprehensive taxonomic characterization. Phylogenetic analysis based on 16S rRNA gene sequencing, along with genome-based comparisons using average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), average amino acid identity (AAI), and phylogenomic analysis, supported by detailed phenotypic profiling, confirmed the bacterium as a novel member of the genus Bacillus. Functional screening revealed that an intracellular protein fraction (~ 67 kDa) derived from this isolate exhibited potent anticancer activity against cervical and triple-negative breast cancer cells in vitro. Mechanistic studies demonstrated that the protein fraction suppresses cancer cell growth by inducing apoptosis, arresting cell cycle progression, and inhibiting colony formation and migration. Additionally, it modulated the expression of key cancer-associated proteins involved in survival, proliferation, and metastasis. Taken together, this work not only establishes the taxonomic and microbiological identity of a novel Bacillus isolate but also underscores its therapeutic promise as a source of anticancer proteins.