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

Abstract

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.

Exploring the potency of Streptomyces koyangensis strain SHP 9-3 isolated from the soil of Enggano Island (Indonesia) as an antibacterial source

“…Our preliminary research supports further investigation of the isolate SHP 9-3, which showed prominent broadspectrum antimicrobial activity (Pahira et al 2020). Based on the 16S rRNA analysis, the isolate was identified as S. koyangensis SHP 9-3.…”

“…The S. koyangensis strain SHP 9-3 was isolated from the soil of Enggano Island, Bengkulu, Indonesia (Pahira et al 2020). Cultivation of S. koyangensis SHP 9-3 was carried out on the International Streptomyces Project-2 (ISP-2) media (consisting of 4 g yeast extract, 10 g malt extract, 4 g glucose in 1 L water, pH 7.0) for 7-14 days at 37°C (Ratnakomala et al 2016).…”

“…Scanning Electron Microscopy (SEM) observation was performed on the isolate after 14 days of incubation at 30°C (Ratnakomala et al 2016;Pahira et al 2020). The bacterium shows a spherical shape, a long spiral chain colony, and fine hyphae (Figure 2).…”

“…This follow-up research was based on a preliminary screening of actinomycetes isolated from Enggano Island's soil (Pahira et al 2020). This study focused on the most promising isolate SHP 9-3.…”