The Effect of Bifidobacterium Longum on Expression of Hfq in Escherichia Coli O157:H7

Background and Aim: Escherichia coli (E. coli) O157:H7 is the primary cause of food poisoning and urinary tract infection via Shiga toxin. The main transcription factor for Shiga toxin is Hfq gene. It is reported that probiotics can reduce the production of toxin substances in pathogenic bacteria. This study was aimed to investigate the influence of Bifidobacterium longum (B. longum) on the expression level of the Hfq gene as the main virulence factor in E. coli O157:H7. Materials and Methods: B. longum was cultured in MRS (De Man, Rogosa, and Sharpe) medium. Different concentrations of B. longum was co-cultured in Mueller-Hinton Agar (MHA) along with E. coli in different time points. Total RNA was extracted followed by synthesizing cDNA. The Hfq gene expression was evaluated by SYBR Green real-time PCR. The 16S ribosomal RNA was used as an internal control for data normalization. Results: The results showed reduction in E. coli growth at different co-culture time points with B. longum . Molecular analysis demonstrated that B. longum has the ability to significantly reduce the expression of Hfq virulence gene (P=0.0023). Conclusion: Probiotic bacteria inhibit the growth of pathogenic bacteria by producing bacteriocins and reducing the expression level of the virulence genes. They can also play role in inhibiting intoxications and infections caused by E. coli.

Bifidobacterium longum, E. coli, Hfq gene, Probiotics