en میکروب شناسی مولکولی Molecular Microbiology مقاله پژوهشی Original Research Article <p>&nbsp;</p> <p style="text-align: justify;"><span style="font-size:16px;"><span style="font-family:Times New Roman;"><span style="line-height:150%"><b><span style="line-height:150%"><span new="" roman="" times="">Background and Aim:</span></span></b><span style="line-height:150%"><span new="" roman="" times=""> <i>Escherichia coli</i> (<i>E. coli</i>) O157:H7 is the primary cause of food poisoning and urinary tract infection via Shiga toxin. The main transcription factor for Shiga toxin is <i>Hfq</i> 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 <i>Bifidobacterium</i> <i>longum </i>(<i>B.</i> <i>longum</i>) on the expression level of the <i>Hfq</i> gene as the main virulence factor in <i>E. coli </i>O157:H7.</span></span></span><br> <span style="line-height:150%"><b><span style="line-height:150%"><span new="" roman="" times="">Materials and Methods:</span></span></b><span style="line-height:150%"><span new="" roman="" times=""> <i>B. longum</i> was cultured in MRS (De Man, Rogosa, and Sharpe) medium. Different concentrations of <i>B.</i> <i>longum</i> was co-cultured in Mueller-Hinton Agar (MHA) along with <i>E. coli</i> in different time points. Total RNA was extracted followed by synthesizing cDNA. The <i>Hfq</i> gene expression&nbsp; was evaluated by SYBR Green real-time PCR. The 16S ribosomal RNA was used as an internal control for data normalization.</span></span></span><br> <span style="line-height:150%"><b><span style="line-height:150%"><span new="" roman="" times="">Results:</span></span></b><span style="line-height:150%"><span new="" roman="" times=""> The results showed reduction in <i>E. coli</i> growth at different co-culture time points with <i>B.</i> <i>longum</i> . Molecular analysis demonstrated that <i>B.</i> <i>longum</i> has the ability to significantly reduce the expression of <i>Hfq</i> virulence gene (<i>P</i>=0.0023).</span></span></span><br> <span style="line-height:150%"><b><span style="line-height:150%"><span new="" roman="" times="">Conclusion:</span></span></b><span style="line-height:150%"><span new="" roman="" times=""> 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 <i>E. coli</i>.</span></span></span></span></span></p> Bifidobacterium longum, E. coli, Hfq gene, Probiotics 278 286 http://ijmm.ir/browse.php?a_code=A-10-2470-3&slc_lang=en&sid=1 Sobhan Aboulhassanzadeh sobhan.aboulhassanzadeh2@mail.dcu.ie 100319475328460030729 100319475328460030729 Yes School of Biotechnology, Faculty of Science and Health, Dublin City University, Dublin, Ireland Samin Aboulhassanzadeh Samin.Aboulhasanzadeh@gmail.com 100319475328460030730 0009-0002-5663-8794 No Mérieux NutriSciences - Global, Advanced laboratory testing, Newbridge, Ireland Hamed Aghazadeh Hamed.Aghazadeh@ut.ac.ir 100319475328460030731 100319475328460030731 No Research Center for Pharmaceutical Nanotechnology (RCPN), Tabriz University of Medical Sciences, Tabriz, Iran Zahra Nikkhooy nikkhooyzahra@gmail.com 100319475328460030732 0009-0002-7132-2085 No Department of Biology, Faculty of Science, Shahid Chamran University, Ahvaz, Iran Behboud Jafari Be.jafari@iau.ac.ir 100319475328460030733 100319475328460030733 No Department of Microbiology, Ahar Branch, Islamic Azad University, Ahar, Iran