Impairment of Swimming Motility by Antidiarrheic Lactobacillus acidophilus Strain LB Retards Internalization of Salmonella enterica Serovar Typhimurium within Human Enterocyte-Like Cells

Abstract

ABSTRACTWe report that both culture and the cell-free culture supernatant (CFCS) ofLactobacillus acidophilusstrain LB (Lactéol Boucard) have the ability (i) to delay the appearance ofSalmonella entericaserovar Typhimurium strain SL1344-induced mobilization of F-actin and, subsequently, (ii) to retard cell entry byS. Typhimurium SL1344. Time-lapse imaging and Western immunoblotting showed thatS. Typhimurium SL1344 swimming motility, as represented by cell tracks of various types, was rapidly but temporarily blocked without affecting the expression of FliC flagellar propeller protein. We show that the product(s) secreted byL. acidophilusLB that supports the inhibitory activity is heat stable and of low molecular weight. The product(s) caused rapid depolarization of theS. Typhimurium SL1344 cytoplasmic membrane without affecting bacterial viability. We identified inhibition of swimming motility as a newly discovered mechanism by which the secreted product(s) ofL. acidophilusstrain LB retards the internalization of the diarrhea-associated pathogenS. entericaserovar Typhimurium within cultured human enterocyte-like cells.