Diversity and antimicrobial activity of culturable endophytic actinobacteria associated with Acanthaceae plants

Abstract

In this study, a total of 52 endophytic actinobacteria were isolated from 6 species of Acanthaceae plants collected in Thailand. Most actinobacteria were obtained from the root part. Based on 16S rRNA gene analysis and phylogenetic tree, these actinobacteria were classified into 4 families (Nocardiaceae, Micromonosporaceae, Streptosporangiaceae and Streptomycetaceae) and 6 genera including Actinomycetospora (1 isolate), Dactylosporangium (1 isolate), Nocardia (3 isolates), Microbispora (5 isolates), Micromonospora (10 isolates) and Streptomyces (32 isolates). The result of antimicrobial activity screening indicated that 8 isolates, including 1 Actinomycetospora and 7 Streptomyces, exhibited antimicrobial activity against tested microorganisms. In addition, the selected Streptomyces sp. 5R010 showed antagonistic activity against fungal plant pathogens including Fusarium sp., Colletotrichum sp. and Sclerotium sp. Therefore, this study demonstrated that the Acanthaceae plant species harbored the endophytic actinobacteria which can be used as the source of the antimicrobial compound.