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Antimicrobial characteristics and taxonomical diversity among actinomycetes isolated from Catba island, Vietnam

This study aimed to investigating biodiversity and to screening actinomycete strains exhibiting high antimicrobial activity among a collection of actinomycetes isolated from Catba island, a national park with rich biodiversity in Viettiam. | Tgp chi Cong nghi Sinh hoc 10( 1): 159-168, 2012 ANTIMICROBIAL CHARACTERISTICS AND TAXONOMICAL DIVERSITY ACTINOMYCETES I S O L A T E D FROM CATBA ISLAND, VIETNAM AMONG Le Phuong Chung', Nguyen Quynh Llyen\ Nguyen Huynh Minh Quycn\ Nguyen Thi Van^ Dinh Thuy Hang^ 'Nhatrang University ^Institute of Microbiology and Bioleclmolog\>. Vietnam National University Hanoi ABSTRACT In this shjdy. 424 acUnomycete stniins isolated from soil and lilter samples on Calba island (Haiphong, Viemam) were subjected to Ihe screening for the inhibitory aelivilies against microorganisms, including baclena (Micrococcus luleus, and Escherichia coli) and cukarui (Candida albicans and Fusarium oxysporium) Through two screening steps. 17 strains were selecled for their high inhibitory activity against one or more target microorganisms Crude extracts in ethyl acclatc from culluring media of the selecled strains were analyzed via thin-layer chromatography (TLC) and high pcrform.mce liquid chromatography (HPLC), in which chloramphenicol, kitasamycin, erythromycin and raw extract of anthracycline were used as standards. The obtained results showed that antibiotic substances produced by ihc selecled strains could not be put in any group of the analyzed standards, except the strain A396 which appeared to produce a chloramphenicol-like antibiotic Taxonomical studies based on the morphology and I6S rONA sequencing indicated that the collection of actinomycetes isolated from Calba island contained mainly S/re/j/omjcej species (about 70%) and the group of rare actinomycetes (non-Streptomyces) which made of 30% of the collection was dominated by Micromonospora, Nonomureae and Nocardia genera. Of the 17 selected strains with highest antimicrobial activity, ten strains were affiliated to the genus Slreptomyces (as based on the morphology) and seven strains belonged to the genus Nonomuraea (as based on 16S rDNA sequence analyses) The strains selected in this study could serve as sources for discovering