In vitro antagonistic effect of probiotic LAB isolated from traditional fermented products against some antibiotics resistant food borne pathogens

Abstract

Infections associated with foodborne microbial pathogens are the major causes of morbidity and mortality in the world's populations. Most of the pathogens especially bacteria have developed new resistances to the most commonly used antibiotics. In order to avoid the use of antibiotics, it is necessary to look in to an alternative way of treating the pathogens through the uses of probiotics. The aim of this study was to isolate probiotic LAB form traditionally fermented products and evaluating their antagonistic effect against antibiotics resistant foodborne pathogens such as, E. coli, Salmonella and Shigella. Accordingly sixteen (16) probiotic LAB were screened from traditionally fermented ergo and Tej. The selected isolate were screened based on their probiotic attributes of acid tolerance, bile salt tolerance, starter culture attributes and their antagonistic effect against antibiotics sresistant E.coli, Salmonela and Shigella. Inhibitions using cell-free liquid cultures of LAB on solid cultures of pathogens, showed a growth inhibition against nine antibiotic resistant pathogens diameter equal or greater than 7mm in well diffusion assay. The isolate showed a relative strong inhibition activity, moderate inhibition activity to low inhibition activity (inhibition zone < 10mm) against antibiotics resistant pathogens in well diffusion method. Each LAB co-cultured in milk separately with each nine antibiotic resistant pathogens showed antagonistic activity against the pathogens during the course of fermentation. The highest reduction in the number of pathogens was observed during 48hrs of fermentation of Ergo. The reduction in the number of growth of pathogens by each LAB isolate was significantly (P< 0.05) higher than the control fermented Ergo at 24hrs and 48hrs of fermentation. The use of these isolate at home made production of Ergo could help to control the proliferation of antibiotic resistant disease causing bacteria and could also serve as traditional way of treating the pathogens through the uses of fermented Ergo. Fermented products are rich in probiotic bacteria, therefore consuming fermented Ergo add a beneficial bacteria and enzymes to overall intestinal flora, increasing the health of gut microbiome and digestive system and enhancing the immune system.