ISOLATION AND IDENTIFICATION OF MYCOBACTERIUM FROM RAW MILK AND TRADITIONAL CHEESE SAMPLES COLLECTED FROM DAIRY STORES IN KARAJ, IRAN

Background and Aim:Milk and its products are one of the nutritious food that is necessary for human body. However, consumption of unpasteurized dairy products can be a source of concern for the transmission of pathogens. Among these pathogens, Mycobacterium is a significant contaminant present in milk that can be lead to tuberculosis disease in human. The aim of present study was to isolate and identify Mycobacterium species in unpasteurized cow milk and cheese samples collected from Karaj city in Iran.Methods:Forty raw milk and traditional cheese samples collected from dairies in Karaj city were transported to Tuberculin department, Razi Institute. All samples were decontaminated by NaOH (1N) and cultured on Lowenstein-Jensen and Herrold’s egg medium, at 37ºC for at least 8 weeks. DNA was extracted from pure colonies by the method of Van Solingen. The extracted DNA was subjected to 16SrRNA genus-specific primer pairs in a PCR reaction. The samples showing a bond of approximately 543bp were considered Mycobacterium positive. All positive samples are further being analyzed for identifying the Mycobacterium species.Results:Among the forty collected samples, 7 milk and 2 cheese samples appeared Mycobacterium positive by PCR method using 16SrRNA primers. However, by culture method only 2 milk and 2 cheese samples appeared positive.Conclusion:Dairy products might be a source of Mycobacterium contamination, especially unpasteurized dairy products. Additionally, 16S rRNA PCR method is a suitable method for rapid and reliable detection of Mycobacterium.

Keywords:

Mycobacterium , dairy products , 16S rRNA , PCR