SELECTIVE ISOLATION OF Dactylosporangium AND Micromonospora FROM THE SOIL OF KARST CAVE OF SIMEULUE ISLAND AND THEIR ANTIBACTERIAL POTENCY

Abstract

Karst is a unique ecosystem that consists of a thin soil layer on the carbonate rocks. It has a diverse microorganism, especially actinomycetes group, which might potentially produce beneficial secondary metabolites that remain unknown. In this study, we were interested in isolating Dactylosporangium and Micromonospora that have been potentially reported as antibiotic sources. We used two methods using the chemical germicide (pretreatment 1.5% phenol) compared with the SDS-YE (0.05% SDS pretreatment). Thirty-nine isolates actinomycetes were successfully isolated from two samples of the karst cave soils. Thirteen isolates were obtained by using the germicide chemical method and closely related to the genera of Dactylosporangium and Micromonospora. On the other hand, the SDS-YE grew twenty-six isolates which closely related to 11 genera of actinomycetes (Catenulispora, Nocardia, Rhodococcus, Ornithinimicrobium, Catellatospora, Dactylosporangium, Micromonospora, Streptacidiphilus, Streptomyces, Nonomuraea, and Streptosporangium). These results suggest that 1.5% of phenol pretreatment could preserve the genera of Dactylosporangium and Micromonospora, while the Streptomyces and other rare actinomycetes were killed. Among all isolates, only 7 showed the antibacterial activity on tested bacteria. Even though the antibacterial activity of those isolates was not high, the isolation of actinomycetes from a specific substrate is necessary to be conducted on exploring the richness of our natural resources.

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

“…Enggano Island, North Bengkulu Province, is Indonesia's outermost island located in the Indian Ocean. The island is composed of weak wavy hills, karst hills, soils, and swamps, whereas the mainland area is dominated by cambisol, and alluvial soil types, with thick texture plates [8]. The diverse characteristics of the land cause the island to have a unique ecosystem.…”

“…The diverse characteristics of the land cause the island to have a unique ecosystem. The differences in environmental conditions, climate, and ecology, will affect the type of microbes in Enggano Island including the actinomycetes group [8].…”

“…Three families, i.e., Micromonosporacea, Streptomycetaceae, and Streptosporangiaceae and eight genera were found from these samples. Approximately 80% of these strains belonged to the Streptomyces group, and 20% of the isolates were similar to rare actinomycetes [8]. Furthermore, Ratnakomala et al were successfully isolated 29 actinomycetes from three different mangrove sediment samples in Enggano Island and evaluated their antimicrobial activity.…”

Diversity of actinomycetes on plant rhizosphere of karst ecosystem of Gorontalo, Indonesia

“…Nurkanto (2007) reported that some kinds of actinomycetes are capable of solubilizing phosphate, including member genera Nocardia sp., Streptomyces, Micromonospora sp., Actinoplanes sp., Microbispora sp., Microtetraspora and Streptosporagium sp. Putri and Sumerta (2020) also found about eleven genera of actinomycetes from the karst cave soils of Simeulue island, one of which is Streptomyces. Streptomyces griseorubens BC10 and Nocardiopsis alba BC11 are promising candidates as phosphate solubilizing bacteria (Boubekri et al 2021).…”

“…Plants in the karst ecosystem, bacteria were found associated with bacteria in their root systems, including actinomycetes and non-actinomycetes groups. According to Putri and Sumerta (2020), there are 11 genera of actinomycetes found in the karst ecosystem of Semeulue Island. Elshafie and Camele (2022), also reported that the root system of rosemary, acacia, strawberry, and olive was associated with some kinds of actinomycetes strains.…”