---

Background and Aim: Aran-bidgol Lake is one of the hypersalin lakes in Iran that is full of black mud in most seasons. Studies have shown that this type of mud is rich in minerals and natural antibiotics, and has the potential to be used in the treatment of various diseases. The aim of this study was to investigate the physicochemical properties and antimicrobial activity of black mineral mud isolated from Aran Bidgol salt Lake, on several common antibiotic resistant pathogens. Material and Method: We used XRD and XRF tests to investigate the physicochemical properties of the mud. We prepared serial mud concentrations of 0.01 to 0.6 g/ml in Mueller Hinton Agar and used minimal bactericidal concentration (MBC) test to investigate the antibacterial activity of the mud, against drug-resistant strains of P. aeruginosa, A. baumannii, E. coli and S. aureus. Results: Comparison of the physicochemical properties of this mud with those of the commercial sample (Fango) showed that the percentages of inorganic compounds are similar in the mud isolated from Aran-Bidgol Lake and Fango mud, but the percentages of Na+ and Cl- ions were higher in Aran-Bidgol mud sample. Evaluation of the antimicrobial activity of the Aran-Bidgol mud showed that more than 90% of the strains were susceptible to the mud at MBC 4 g/ml. Conclusion: According to the results of this study, this mud is suitable for the successful commercial purposes and use in mud therapy clinics. Keywords: Mineral Mud, Aran-Bidgol, Antibacterial, Physicochemical Received: Jun 8, 2013 Accepted: Jan 21, 2014