Effect of Probiotic on the Survival of Non-O157 Shiga Toxin-producing E. coli (STEC) Strains in African Fermented Weaning Food Products

Introduction: Ogi is a fermented maize gruel in Nigeria and the commonest traditional fermented weaning food in many communities of West African while motoho is a fermented sorghum beverage commonly produced in Southern Africa countries. High prevalence of diarrheal diseases, among infants in developing countries coupled with the occurrence of pathogenic E. coli in fermented foods, is an indication of an underlying safety problem.

Purpose: In this study, the ability of probiotic bacteria to inhibit acid tolerant non-O157 STEC strains from environmental sources was investigated in ogi and sorghum motoho.

Methods: Ogi was processed by steeping the maize grains spontaneously and also with probiotic (L. plantarum-B411) for 72 h followed by souring (after wet milling and sieving) for 48 h while the probiotic (L. plantarum-FS2 and P. pentosaceus-D39) strains developed from ogi fermentation were used for the processing of sorghum motoho. All samples were inoculated with acid adapted (AA) or non-acid adapted (NAA) non-O157 STEC strains. 

Results: The growth of AA and NAA non-O157 STEC strains were significantly (P ≤ 0.05) inhibited in the spontaneous combined with probiotic fermented ogi, while AA non-O157 STEC strains were more significantly (P ≤ 0.05) inhibited than NAA non-O157 STEC strains in the fermented sorghum motoho after 24 h. 

Significance: Probiotic bacteria coupled with prior adaptation to acid i.e., backslopping are more effective in controlling the occurrence of environmental acid tolerant non-O157 STEC strains in traditional fermented weaning foods than the usual uncontrolled spontaneous fermentation.