The aim of this research was to study on the identification and antimicrobial activity of thirteen actinomycete strains isolated from peat swamp forest soils collected from Narathiwat, Patthaloong and Yala provinces, the southern part of Thailand. Based on the phenotypic and chemotaxonomic characteristics, all isolates were belonged to genus Micromonospora. They were separated into six groups based on 16S rRNA gene sequence analysis and were identified as M. narathiwatensis (Group 1, 5 isolates), M. humi (Group 4, 3 isolates), M. aurantiaca (Group 5, 2 isolates), one of each isolate as M. chalcea (Group 2) and M. maritima (Group 6). The isolate LK6-12 (Group 3) showed low similarity (99.16%) with the type strains of Micromonospora siamensis that will be the novel species of the genus Micromonospora. The tested strains contained meso-diaminopimelic acid in cell wall (cell wall type II), xylose and arabinose as diagnostic whole-cell sugar pattern D, and phosphatidylethanolamine as characteristic phospholipid (type II). The major fatty acids of the tested strains were iso-C16:0, iso-C15:0, iso-C17:0, anteiso-C16:0, anteiso-C15:0, and anteiso-C17:0. Their major menaquinones were MK-9(H4), MK-9(H6), or MK-10(H4). The range of DNA G+C content of isolates was 71.6-72.6 mol%. On the primary screening, 2 isolates exhibited the antimicrobial activity against Bacillus subtilis ATCC 6633 and Kocuria rhizophila ATCC 9341.
Key words: Actinomycetes, antimicrobial activity, Thai peat swamp forest, soils, Micromonospora
|
