Identifying Antibiotic-Producing Streptomyces Species in Iran’s soil by Phenotypic and Genotypic Methods

摘要

Introduction: Actinomycetes are gram-positive and filamentous bacteria which contain most microorganisms in the soil. According to the research, three-quarters of all known antibiotics are produced by Actinomycetes. In this regard, screening for antibacterial activities as well as identify them, 16S rRNA gene and phenotyping methods were used.udThe aim of this study was to evaluate actinomycetes in different parts of Iran for their antimicrobial properties and also identifying the active strain using 16S rRNA gene and phenotypic methods.udMethods: actinomycetes isolates were separated from the gathered soil samples; initial screening have done using cross streak method in agar culture and second screening have done using disk diffusion method against the studied microorganisms: S. aureus, ATCC 25923 and E.coli ATCC 25922. Final confirmation of the produced antibiotic has been conducted by HPLC and identification of strains was done with PCR and DNA sequencing.udResults: From 100 gathered soil samples, 52 actinomycete isolates were separated; 30 isolates for primary screening and 3 isolates for secondary screening were selected. Strain 28 had a peak (RF) similar to gentamicin and isolates 34 and 4 strains had similar peak (RF) to streptomycin. 16S rRNA genes of isolates were sequenced, in which isolate 28 had 99.93 percent similarity to Streptomyces youssoufiensis and isolate 4 had 99.93 percent similarity to Streptomyces cyaneofuscatus. udConclusion: The results showed that there are new isolates in the soil samples of Iran that have the ability to produce antibacterial substances.udKeywords: Streptomyces, Antibacterial material, separation from soil, 16 S rRNA genes