Presumptive probiotic bacteria from traditionally fermented African food challenge the adhesion of enteroaggregative E. coli

Abstract

AbstractColonization of intestinal tract with the potential to exclude, displace, and inhibit enteric pathogens is principally dependent on the adhesion ability of probiotics. Therefore, probiotic efficacy is considered to be mainly determined by their adhesion ability. The current study reports the antagonistic effect of four lactic acid bacteria (LAB) on the adhesion profile of four diarrhoeagenic and one non‐diarrhoeagenic enteroaggregative Escherichia coli (EAEC). All the bacterial strains investigated adhered to the Caco‐2 cells. All the LAB tested competitively excluded, displaced, and inhibited at least three (non‐) diarrhoeagenic EAEC strains from adhesion (p < 0.05). In all, Lactobacillus plantarum, FS2 exhibited the strongest adhesion to the Caco‐2 cells, competitive exclusion (CE), displacement, and inhibition against most of the EAEC strains. Additionally, the competence to exclude, displace, and inhibit the EAEC from adhesion depended on both the pathogens and the LAB strains tested; signifying the participation of several mechanisms. Contrary to all the EAEC strains, gastro‐intestinal stress factors such as low pH (2.5) had no effect on the adhesion of the LAB. Unlike the gastro‐intestinal acidic conditions, bile salt conditioning (at pH 6.5) had no effect on the adhesion of both EAEC and LAB. In conclusion, all the LAB tested showed specific anti‐adherence effects including CE, displacement, and inhibition against the selected EAEC. The results indicate that all the LAB, particularly, the L. plantarum, FS2 had a good ability for exerting antagonistic effects against the selected EAEC for the prevention of gastrointestinal infection.