Bacillus toyonensis BAR1, a yellow-pigment producing endophyte of Berberis aristata DC: a potential source of bioactive and antimicrobial compounds.

Herein, we report the isolation and characterization of an endophytic bacterium associated with the Berberis aristata roots to uncover bioactive compounds, particularly antimicrobials, using submerged culture. The bacterial isolate was identified via 16S rDNA sequence analysis and characterized using morphological, microscopic, and biochemical techniques. It was identified as Bacillus toyonensis strain BAR1, a motile, gram-positive, halotolerant bacterium capable of producing yellow pigments. The isolate was cultured under submerged fermentation conditions for secondary metabolites production, followed by their extraction, identification, and in-vitro biological activities evaluation. Colorimetric phytochemical analysis of crude secondary metabolite extract revealed diverse phytochemical classes, including phenolics, alkaloids, tannins, and terpenoids. UV-visible spectrophotometry of the extract identified two yellow pigments, carotenoids and berberine, while GC-MS-based metabolomic profiling detected several important bioactive compounds and peptides, including calein C, carnegine, and deoxyspergualin. The extract demonstrated significant concentration and time dependent antioxidant and antibacterial activities, particularly against multidrug-resistant Enterobacter cloacae, Bacillus subtilis, and Pseudomonas aeruginosa. In conclusion, Bacillus toyonensis BAR1 is a potential microbial factory for sustainable production of bioactive compounds and yellow pigments, with promising applications in pharmaceuticals, textile and food industries, pending further validation.