Evaluation of the probiotic attributes of Bacillus strains isolated from traditional fermented African locust bean seeds (Parkia biglobosa), "daddawa"

Abstract

Background: The involvement of probiotic cultures in food fermentation guarantees enhanced organoleptic properties and maximum consumer health benefits. In this study, isolated Bacillus cultures used in the fermentation of African locust bean seeds "Parkia biglobosa" into the food condiment "daddawa" were evaluated for probiotic attributes. Bacillus cereus strains BC1 and BC2 were tested for tolerance to acid, common salt (NaCl), and bile salt. Auto-aggregation and adhesion to epithelial cells, antibiotic sensitivity profile, hemolytic pattern, and antibacterial activity were also evaluated. To demonstrate further health benefit, spores of strain BC1 were investigated for anti-inflammatory potential employing the rat paw edema technique. Results: Both Bacillus cereus strains showed antagonistic activity against pathogenic Escherichia coli and Staphylococcus aureus. BC1 was more acid-stress tolerant than BC2, maintaining 107.6% viability after 3 h incubation in MRS broth of pH 2.5. However, at 97.74% viability after incubation for 3 h, BC2 was more tolerant to 0.4 % bile salt. The Bacillus cereus strains were susceptible to all antibiotics tested with the exception of norfloxacin and thrived under high saline stress. Both strains were protease producers and non-hemolytic on sheep blood agar. The edema inhibition study revealed that spores of Bacillus cereus strain BC1 had anti-inflammation potential and produced no physiological toxicity on the animals. Conclusion: These results indicate that the Bacillus cultures for "daddawa" production are good candidates for probiotics and have the potential for application in both animal and human formulations for increased health benefit to consumers.