Probiotic Characterization and Antimicrobial Activity of Bacillus Species Isolated from Traditionally Fermented Parkia biglobosa Seeds in Nigeria

Abstract

With the advent of rising antimicrobial resistance and the development of functional foods, efforts have been made to search for indigenous microorganisms with functional and antimicrobial properties. In West Africa, traditionally fermented African locust bean (Parkia biglobosa) seeds are an important source of beneficial microorganisms. In this study, the probiotic potential and the antimicrobial activity of the bacterial isolates obtained from the fermented seeds of P. biglobosa were evaluated. Culture-dependent methods were used to isolate bacteria, and biochemical methods and 16S rRNA gene sequencing were used to identify each bacterial isolate. Salt tolerance, bile salt tolerance, temperature tolerance, and antimicrobial activity against Escherichia coli, Proteus vulgaris, Salmonella typhi, and Serratia marcescens were performed to assess the probiotic properties of the microorganisms. Antibiotic susceptibility profiles were also performed. Molecular identification identified eight bacterial isolates of Klebsiella pneumoniae, Bacillus paramycoides, Bacillus subtilis, Bacillus velezensis and Bacillus licheniformis. Bacillus isolates showed improved probiotic characteristics of growth at 6% NaCl, surviving at 110-112% in bile salts (0.3%) and excellent growth on 25-45°C. However, K. pneumoniae isolates had a lower level of bile stress tolerance with 77–78% of strains surviving. Antimicrobial assays results indicated that there were significant difference among isolates (p<0.001), in which B. velezensis and B. licheniformis showed highest antimicrobial property against all test pathogens. The highest inhibition zones were observed against S. typhi (20.80 mm) and E. coli (20.27 mm). The antibiotic susceptibility profile of these isolates were also good. The results show that fermented P. biglobosa is a potential source of functionally important species of Bacillus with probiotic and antimicrobial properties. These indigenous strains can be used as the potential candidates for probiotic foods, biopreservatives development and as supplements for antimicrobial interventions.

Keywords: Parkia biglobosa, probiotics, Bacillus velezensis, Bacillus licheniformis, antimicrobial activity, fermented foods

DOI: 10.7176/JBAH/16-2-06

Publication date: August 31^st 2026