Seyed ali Alavi - Department of biology, University of Maragheh, Maragheh, East Azerbaijan, Iran
Amir Abbas Barzegari - Department of biology, University of Maragheh, Maragheh, East Azerbaijan, Iran
Seyed Babak Khalifeh Zadeh Kaleybar - Department of Pathology, Islamic Azad University, Tabriz Branch, Tabriz, Iran
Farshad Darvishi - Department of biology, University of Maragheh, Maragheh, East Azerbaijan, Iran

Background and Aim : Probiotics may be a good alternative to antibiotics in fighting pathogenic bacteria. The current study aimed to evaluate the antibacterial activity of Lactobacillus rhamnosus cell-free supernatant against Staphylococcus aureus and Escherichia coli.Methods : L. rhamnosus ATCC ۷۴۶۹ was cultured in the MRS broth medium at ۳۷˚C. The medium was transferred to the tube after ۴۸ h and centrifuged at ۸۰۰۰ rpm for ۲۰ minutes. The supernatant was passed through a filter with ۰.۲ μm pores under sterile conditions. The antibacterial activity of the filtered supernatant was determined against S. aureus ATCC ۲۵۹۲۳ and E. coli ATCC ۸۷۳۹ by minimum inhibitory concentration (MIC) method.Results : The minimum inhibitory concentration of L. rhamnosus cell-free supernatant against S. aureus and E. coli was ۲۵ and ۱۲.۵ microliter/ml, respectively.Conclusion : The cell-free supernatant of L. rhamnosus had a good antibacterial effect on S. aureus and E. coli.

Lactobacillus rhamnosus, Escherichia coli, Staphylococcus aureus, Antibacterial activity