Selective screening Lactobacillus spp. against Escherichia coli and Salmonella Typhimurium and optimizing a cane molasses-based medium with Lactobacillus acidophilus as a guiding model

Abstract

BackgroundThe overuse of antibiotics in livestock farming has led to the emergence of antibiotic resistance, which poses a significant threat to human health. Probiotics have gained increasing popularity as an alternative to antibiotics, prompting the exploration of cost-effective fermentation substrates for large-scale production. MethodsThis work aimed to investigate the antimicrobial effect of probiotics lactic acid bacteria (LAB) against various pathogenic bacterial strains (e.g. S. Typhimurium O66, S. Typhimurium S251, E. coli O78:K80 and E. coli O157:H7). A total of 28 bacterial isolates were obtained from fermented food sources, in conjunction with 12 identified LAB strains, were screened for antimicrobial activity using microdilution broth method. The chosen probiotic strain, Lactobacillus acidophilus, was subsequently cultivated in a medium formulated with cane molasses to assess its suitability for probiotic production. Significant findingsThe results demonstrated that most LAB strains inhibited S. Typhimurium and E. coli by over 90 %. In the optimized cane molasses-based medium containing 16.02 % (v/v) molasses, 10 g/L (w/v) yeast extract with pH of 6.6, a cell dry weight (CDW) of 3.63 g/L of L. acidophilus was achieved. Therefore, cane molasses emerged as a promising alternative carbon source for LAB biomass production, offering the potential to reduce production costs while minimizing waste generation.