Abstract
Background and Objectives: Actinomycetes, the most widely distributed groups of microorganisms in nature, produce three fourth of antibiotics. Among these, streptomyces are of great importance. Therefore, we aimed at screening for antibacterial activities and molecular identification of isolated streptomyces in East Azerbaijan soils using 16S rDNA gene.
Materials and Methods: Actinomycetes were isolated from soil samples of East Azerbaijan province. In primary screening bilayer method was used against test microorganisms namely B. cereus, E. coli, S. aureus, Y. enterocolitica, L. monocytogenes, K. pneumoniae, and S. flexneri. On secondary screening, isolates with strong antibacterial activity were selected for secondary metabolite fermentation. These metabolites were tested by disk diffusion method against the same microorganisms. For molecular recognition, the genomic DNA of the selected bacteria was extracted and the 16SrDNA genes were amplified and then sequenced. The sequences of 16SrDNA were studied based on bioinformatics assays.
Results: Three hundred and ten actinomycetes were isolated out of 110 soil samples. In the primary screening, 44 showed antibacterial activity. Of these, 12 isolates were assessed in the secondary screening. The sequences of the 16SrRNA gene revealed that the isolate SC91 was similar to S. sampsonii with 97% 16SrDNA sequence similarity; the isolate SF51 with 82% to Streptomyces lividans; the isolate SG41 with 96% to Streptomyces mediolani; and the isolate was similar to Streptomyces albogriseolus with 98% similarity. The latter was registered in NCBI database.
Conclusion: Results of this research suggest that the soil samples of different regions in East Azerbaijan have potentially unknown and novel species of streptomyces which can be exploited for production of novel antibacterial agents.