Isolation, Identification & Characterisation of Bacillus species from Peruyaan

Abstract

Peruyaan, a traditional fermented soybean product of Arunachal Pradesh, India, contains a diverse microbial community dominated by Bacillus species that drive its biochemical transformation and functional attributes. Understanding the taxonomy and physiology of these strains is essential for developing standardized starter cultures and improving the nutritional and therapeutic value of fermented foods. This study focused on the isolation, identification, and characterization of Bacillus spp. associated with Peruyaan using a polyphasic approach. Fresh samples were collected from local markets and processed through serial dilution and selective plating. Distinct isolates were purified and identified using 16S rRNA gene sequencing. Phylogenetic analysis confirmed the prevalence of Bacillus subtilis, B. amyloliquefaciens, and B. licheniformis, aligning with earlier findings from other fermented soybean foods of Northeast India. Biochemical and enzymatic profiling showed high protease, amylase, and fibrinolytic activities, indicating their role in substrate degradation and bioactive peptide formation. Several isolates also demonstrated antioxidant and antimicrobial properties against common enteric pathogens, supporting the functional food potential of Bacillus-fermented soybeans. The study further highlights that Bacillus-mediated fermentation enhances nutritional components such as isoflavone aglycones, peptides, vitamins, and poly-$\gamma$-glutamic acid ($\gamma$-PGA), as reported in related fermented soybean systems. Overall, these findings suggest that indigenous Bacillus strains from Peruyaan possess strong biotechnological value for controlled fermentations, functional food development, and enzyme production, while providing deeper insight into the microbial ecology of this traditional product.