keywords: Bacillus subtilis, isolate, Fermentation, Rice husk, Poly-γ-glutamic acid
Poly-γ-glutamic (γ-PGA) acid is a multifarious biopolymer and one of the emerging biopolymers that is currently in the centre stage of active investigation. This is because of its unique non immunogenic, nontoxic, water solubility and retention, and availability of functional groups for attachments of other bioactive compounds. This research was aimed at isolating and characterizing strains of Bacillus subtills for the production of low molecular γ-PGA. The B. subtilis isolated from natural habitats (Soil samples were pooled from roots of Sorghum bicolor, water was obtain from Ahmadu Bello University Dan, and Daddawa, a local condiment was purchased from Samaru Market) in Zaria Kaduna State Nigeria. Three isolates of Bacillus subtilis were purified from the collected samples in which only the soil sample gave positive Biochemical inference for B. subtilis. The isolates were further characterized by 16S rRNA gene sequencing. The strains were then used for a preliminary production of poly-γ-glutamic acid in submerge broth. From the three purified isolates designated S1, S4 and S5. Highest yield of 251.67±30.00 mg/gds of γ-PGA by submerge fermentation was obtained from isolate S5. Which was used for solid state fermentation (reported elsewhere). The study shows that Isolate S5 is a suitable candidate showing potential for fermenting low molecular weight γ-PGA, holding promise for industrial applications.