Identification and antimicrobial activities of Streptomyces, Micromonospora, and Kitasatospora strains from rhizosphere soils

Abstract

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 the 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), Streptomyces vietnamensis (2 isolates), Streptomyces bungoensis (2 isolates), each of Streptomyces psammoticus, Streptomyces purpurascens, Streptomyces hydrogenans, Streptomyces lucensis; Micromonospora schwarzwaldensis, Micromonospora chersina, Micromonospora terminalae, Micromonospora chaiyaphumensis, Micromonospora rhizosphaerae and two isolates as Kitasatospora putterlickiae. On the results of antimicrobial activities, three 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 S. psammoticus NBRC 13971 T , this isolate might be the novel species of actinomycetes.