Evaluation of Expression Levels of Virulence Associated luxS, and ctxM Genes in Escherichia coli Isolated from Dairy Products Co-cultured with Bacillus coagulans

Abstract

Objective, The purpose of this study was isolation of E. coli strains from dairy products and evaluation for the presence of luxS, and ctxM genes. In addition, Bacillus spp. were isolated from poultry intestinal tracts and their characters assessed for detection of probiotic bacteria. Finally, the effect of spore forming probiotic bacteria on the expression of luxS, and ctxM gene in E. coli isolates was evaluated.Methods, Ecoli isolates and spore forming bacterium exhibited favorable characters were identified by molecular method using 16SrDNA gene sequencing and the effect of spore forming probiotic bacteria on the expression of luxS, and ctxM gene in co- culture with E. coli isolates was evaluated by Real time-PCR method. Finding, The results obtained indicated that out of 16 E.coli isolates, two strains carried the genes. In addition, one spore forming bacterium isolate showed probiotic characters. The results on molecular identification of the isolates verified the isolation of two strains of E.coli (carried luxS, and ctxM genes) and one strain of Bacillus coagulans. Finally, the expression levels of luxS, and ctxM genes in E.coli in co-culture with Bacillus coagulans isolates diminished significantly (p-value < 0.05).Therefore, it can be interpreted that native spore forming probiotic bacteria can greatly decrease virulence association gene expression of in E.coli and therefore consumption of native probiotics as food supplement can eliminate gastrointestinal diseases cause by E.coli