Probiotic potentials of lactic acid bacteria isolated from fermented sorghum supernatant (omidun) under different fermentation periods

Probiotic bacteria, primarily lactic acid bacteria (LAB), are known to improve gut health, enhance immune responses, and inhibit the growth of pathogenic microorganisms, making them valuable for functional foods. Naturally fermented sorghum is a rich source of these beneficial bacteria. Therefore, this study investigated the probiotic potentials of LAB isolated from the supernatant of fermenting sorghum ( omidun ). Five omidun samples were fermented for 12, 24, 48, 72, and 96 hours to recover LAB strains. The recovered LAB isolates were identified and characterized using morphological and molecular methods, while their antibiotic resistance profiles were also assessed. Furthermore, we examined the effects of different fermentation periods (12, 24, 48, 72, and 96 hours) on the probiotic potential of the isolated LAB, including temperature tolerance, acid resistance (pH), and bile salt tolerance. Our results showed that bacterial counts in omidun ranged from 2.78 × 10⁻³ − 4.1 × 10⁻³ CFU/ml, while coliform counts varied from 0.00–1 × 10⁻⁴ CFU/ml. The dominant LAB strains recovered from the omidun include Lactobacillus plantarum , Lactobacillus sp ., Limosilactobacillus fermentum , and Lactobacillus brevis . Interestingly, biochemical tests confirmed all isolates were oxidase- and catalase-negative, with cocci and bacillary morphologies. Antibiotic resistance tests revealed that LAB fermented for 72 and 96 hours were resistant to gentamicin, ceftazidime, cloxacillin, erythromycin, cefuroxime, ofloxacin, augmentin, and ceftriaxone. Notably, the LAB isolates exhibited different growth patterns at 25, 37, and 40°C over 1- and 3-hour intervals, with all isolates successfully growing at 40°C. All isolates maintained high viability after 3 hours at both pH 2.5 and 4.0, while those fermented for 12–48 hours showed no growth in both bile levels. The findings from this study suggest that omidun is a rich source of LABs, with fermentation duration, especially 72 hours, playing a crucial role in shaping their probiotic potential.