Isolation and Antimicrobial Screening of Actinomycetes from the Soil of Enggano Island, Indonesia

Actinomycetes are filamentous Gram-positive bacteria that potential sources of antimicrobial substances. The aim of this study was to isolate actinomycetes from different soil types in Enggano Island and screened their antimicrobial activity. The phenol method with 802 medium and humic acid vitamin (HVA) medium was used to isolate the actinomycetes. Furthermore, molecular identifications were performed based on 16s rRNA gene sequence. Antimicrobial activity screening was performed against Bacillus subtilis BTCC B.612, Escherichia coli BTCC B.612, Micrococcus luteus BTCC B.552, Staphylococcus aureus BTCC B.611, and Candida albicans BTCC Y.33 by using the agar plug diffusion method. Fifty-six actinomycetes isolates were obtained from 11 soil types. Most of the isolates were Streptomyces genus with species S. hydrogenans, S. coelicolor, and S. koyangensis, which have similarities in the 16S rRNA gene sequence ranging from 98 -100%. Among isolates screened for their antimicrobial activity, five isolates, i.e. SMP 6, SMP 7b, SMP 18, SHP 9-3, and SHP 22-1a showed a potential activity against test microorganisms selected. All of isolates were more active against C. albicans compared with the tested bacteria. Further study will be conducted to isolate active substances against C. albicans.