| 要約: | Manure compost is a unique microenvironment which harbours potential new microorganisms that is able to produce a variety of anti-infective agents. However, the exploration of this ecosystem for actinomycetes and its bioactive secondary metabolites remained understudied. Therefore, this study aims to study the diversity of manure compost actinomycetes and to investigate their antimicrobial potential using conventional disc diffusion method and a modified resazurin microtiter based approach. A collection of 191 actinomycete isolates were recovered from 5 types of manure composts collected around Selangor, Malaysia. Utilizing a combination of micromorphological characteristics and 16S rRNA sequence analysis, the isolated actinomycetes were grouped into 12 genera within 9 families. Streptomyces spp. dominated the culture collection (79.1%) while the rest belonged to the non-Streptomyces group (20.9%), including an unusual isolate from the genus Verrucosispora. The evaluation of antimicrobial activities demonstrated that 21.5% of the isolates exhibited antagonistic effect against at least one of the test microorganisms with strong inhibition observed against fungal strains compared to pathogenic bacteria. A modified resazurin microtiter based assay was also developed and displayed higher sensitivity (40.0%) compared to the disc diffusion assay (26.0%). All ten actinomycete isolates which displayed narrow and broad spectrum effects also produce pigmented extracts. The results demonstrated that manure compost actinomycetes could be a promising source of novel bioactive agents and that the resazurin microtiter based assay is a more sensitive approach in screening antimicrobial properties of large numbers of microbial extracts. © 2015 Academic Journals Inc.
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