Isolation and identification of mycobacteria isolated from raw milk in Tehran based on ۱۶srRNA and hsp۶۵ genes

BACKGROUND AND ABJECTIVEAs an important source of human food, milk can be a carrier of human pathogenic bacteria, including tuberculous and nontuberculous mycobacteria (NTM), in its raw and unpasteurized state.MATERIALS AND METHODSIn this research, ۱۷۵ raw milk samples were collected from traditional dairy stores in ۲۲ regions of Tehran in a ۹- month period from August ۲۰۱۹ to May ۲۰۲۰. Samples were prepared and transferred to a specialized laboratory, where they were inoculated in Lowenstein-Jensen (LJ) medium containing glycerol or sodium pyruvate, as well as Herrold's egg-yolk with and without Mycobactin J. to determine the sample’s identity of samples. The recommended ۱۶S rRNA (۱۴۳۶ bp) and hsp۶۵ (۶۴۴ bp) genes fragments from the positive isolates identified in Ziehl-Neelsen (Z-N) staining were amplified and sequenced using PCR and compared with the sequences of the gene fragments of reference strains available in the global GenBank database ۱۶S rRNA SILVA, ۱۶S rRNA RDP and nBLAST NCBI. …RESULTS AND DISCUSSIONIn case of samples, a total of four bacteria were collected, all of which were found in the genetic differential testing to be NTM, including n=۱ Mycobacterium heraklionense, n=۲ Mycolicibacterium fortuitum, and n=۱ Mycobacterium thermoresistibile.CONCLUSIONThe analysis of the results obtained by isolates sequencing using the ۱۶S rRNA gene showed higher discriminatory power and percentage similarities in the identification of the isolates than the hsp۶۵ gene.

کلیدواژه ها:

Mycobacterium ، Mycolicibacterium. Raw milk. ۱۶S rRNA gene. hsp۶۵ gene