Isolation,Identification and Evaluation of antimicrobial activity of Actinomycetes from marine sediments of Persian Gulf (Hormozgan Province)

Actinomycetes are gram positive and filamentous bacteria and produce major portion of bioactive compounds. The aim of this study was to isolate and identify antibiotic producing actinomycetes from Persian Gulf marine sediments within Hormozgan province territory. Among 3 selected isolation media the M1 medium showed highest efficacy by isolation of 32 colonies. Heat treatment of 100 ºC for 60 min isolated 26 colonies and showed the best result. Approximately 60 Actinomycete isolates were obtained from 10 sediment samples. Evaluation of antimicrobial activity showed that 33, 20 and 30 % of isolates exhibited antimicrobial activity against S.aureus, E.coli and C.albicans respectively.Morphologic, physiologic and chemotaxonomic studies showed that selected potent isolates consist of Ifro12, Ifro 33 and Ifro 47 belonged to Streptomyces genus. Molecular genetic studies based on 16s rRNA gene analysis revealed that Ifro12, Ifro 33 and Ifro 47 exhibited 99 % similarity to S.olivaceus, S.cacaoi and S.variabilis respectively. Phylogenetic analysis showed that Ifro12 and Ifro 47 derived from a common ancestor. The results of present research indicated that these three isolates could be considered as promising candidates for antibiotic discovery researches.