Diversity and functionality of Bacillus and related genera isolated from spontaneously fermented soybeans (Indian Kinema) and locust beans (African Soumbala)

A total of 126 isolates of Bacillus and related genera from indigenous, spontaneously fermented soybeans (Kinema) and locust beans (Soumbala) were characterized with the purpose of defining interspecific, as well as intraspecific relationships among the components of their microflora. B. subtilis was the dominant species, and species diversity was more pronounced in Soumbala than in Kinema. While from Kinema, six species were isolated (B. subtilis, B. licheniformis, B. cereus, B. circulans, B. thuringiensis and B. sphaericus), in Soumbala, the species found were B. subtilis, B. thuringiensis, B. licheniformis, B. cereus, B. badius, Paenibacillus alvei, B. firmus, P. larvae, Brevibacillus laterosporus, B. megaterium, B. mycoides and B. sphaericus. Genomic diversity in the isolates of B. subtilis was investigated by random amplified polymorphic DNA (RAPD) analysis using the polymerase chain reaction (PCR). The RAPD-PCR fingerprint analysis showed a high level of diversity. With more than 90% similarity, all 52 RAPD subdivisions were source and continent-wise homogeneous. Profiles of carbon source fermentation also showed a wide but corresponding phenotypic diversity, largely corresponding with RAPD subdivisions. The various strains were tested for several criteria for functionality in soybean fermentation, viz. protein degradation, pH increase, and development of desirable stickiness caused by viscous exopolymers. Profiles of functionality, based upon estimations of pH, free amino nitrogen and stickiness were associated with genotypic and phenotypic profiles. Notwithstanding the heterogenous fermentation results for some genotypic profiles, a ranking of RAPD groups is possible and can be useful in the further selection and study of B. subtilis strains.