Identification and Antimicrobial Properties of Malaysian Mangrove Actinomycetes

Abstract

The mangrove area is one of the more unique and less studied habitats for the discovery of biologically active secondary metabolites from potential actinomycetes. For this reason, isolation, characterization and screening of antimicrobial properties of actinomycetes from mangrove soils collected at the selected mangrove areas in Malaysia were conducted. A total of 73 actinomycetes were isolated. Of these, 9.6% (direct broth culture) and 8.2% (ethyl acetate extract) of these isolates demonstrated antimicrobial activities active against Staphylococcus aureus, Bacillus subtilis, Candida albicans as well as Saccharomyces cerevisiae by disc diffusion assay. Hexane extracts, however, exhibited no activity. A modified microdilution plate assay showed that 16.4% (ethyl acetate extract) of these strains were able to generate antimicrobial compounds active against Staphylococcus aureus, Bacillus subtilis, and Candida albicans. In addition, morphological observations and 16S rRNA sequence analysis indicate the presence of representative species from at least 3 genera Streptomyces, Pseudonocardia and Saccharomonospora. Thus, Malaysian mangrove soils could be an interesting source to explore for antimicrobial secondary metabolites and considered to have a diversity of marine actinomycetes.