Rhizosphere soils are the major habitat of various bacteria especially the actinobacteria. In this study, 17 actinomycetes were isolated from rhizosphere soil samples collected from plants including Barringtonia racemosa, Albizzia odoratissima, Spondia spinnata and Azadirachta indica. On the basis of 16S rRNA gene analysis (99.0-100% similarity), the isolates were belonged to genera Streptomyces (10 isolates), Micromonospora (5 isolates) and Kitasatospora (2 isolates). They were identified as Streptomyces sioyaensis (2 isolates), S. vietnamensis (2 isolates), Streptomyces bungoensis (2 isolates), each of S. psammoticus, S. purpurascens, S. hydrogenans, S. lucensis; Micromonospora schwarzwaldensis, M. chersina, M. terminalae, M. chaiyaphumensis, M. rhizosphaerae and 2 isolates as Kitasatospora putterlickiae. On the results of antimicrobial activities, 3 isolates presented the good activities against Candida albicans ATCC 10231, and Escherichia coli ATCC 25922, while 10 isolates exhibited the good activities against Staphylococcus aureus ATCC 25923 and 11 isolates exhibited activities against Bacillus subtilis ATCC 6633. Among them, JA03 showed 98.95% similarity of 16S rRNA gene sequence to Streptomyces psammoticus NBRC 13971T this isolate might be the novel species of actinomycetes.
Key words: Antimicrobial activity, actinobacteria, identification, rhizosphere soils
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