Isolation, biochemical characterization and safety screening of potential probiotic lactic acid bacteria from spontaneously fermented cereal products from Western Kenya

The global demand for non-dairy beverages has sky rocketed especially so during this Covid-19 pandemic for potential health benefits. Development of probiotic strains from fermented cereal and legumes with the ability to grow well and adapt to gastrointestinal conditions at the same time possess high therapeutic ability will be a great achievement. This study aimed at isolating and screening probiotic potential Lactic Acid Bacteria (LAB) involved in traditional fermentation of cereals (maize, sorghum and millet). A total of ten isolates were obtained from the cereals out of which five isolates that met preliminary attributes of probiotic bacteria were selected for further investigation. Two isolates SPU2 and FPU1 were found to survive a low pH which is a desirable attribute for the survival of probiotic bacteria in the gut. MPU1, FPU1 and SPU2 are possible thermophiles and can survive at low pH and moderate high salt concentration. The enzymes DNase and gelatinase used to test pathogenicity of a microorganism were not produced by all the isolates in this study. The isolates recorded a high susceptibility to the eight antibiotics. This study also revealed that the tested isolates have the ability to grow well even at the minimum tested pH of 1.0 for 1 and 2 h of incubation, respectively. Most isolates were resistant to 0.3% bile concentration with over 92% survival. FPU1 was more resistant at bile concentration of 1% than all the rest while MPU1 was most resistant at 2% bile salt. Traditionally fermented cereals are potential sources of safe bacteria that can be tried in the production of functional foods.