SCRIPTA BIOLOGICA | VOLUME 4 | NOMER 2 | JUNI 2017 | 131–134 | HTTPS://DOI.ORG/10.20884/1.SB.2017.4.2.433 | https://scri.bio.unsoed.ac.id 131 ANTIBACTERIAL CAPACITY OF Streptomyces ISOLATE FROM A MANGROVE PLANT RHIZOSPHERE Avicennia marina RENDY SETYA WARDANA, DINI RYANDINI, OEDJIJONO OEDJIJONO Fakultas Biologi, Universitas Jenderal Soedirman, Jalan dr. Suparno 63 Purwokerto 53122 ABSTRACT This research was conducted to obtain Streptomyces isolates from Avicennia marina rhizosphere capable of inhibiting E. coli and S. aureus growth, to investigate the capability and the characteristics of its antibacterial compound. This study completed the isolation by applying pour plate method on SCN agar medium. Antagonistic screening and selection processes were carried out by diffusion and dilution methods. Observation on the characteristic of the antibacterial compound applied was TLC method and MIC assay. This research confirmed the antibacterial compound capability by applying bioautography assay. Parameters measured consisted of inhibition zone diameter, Rf value on a bioautography plate, and the lowest concentration capable of inhibiting bacterial growth. Out of 16 isolates of Streptomyces obtained, Streptomyces 404 showed higher antagonistic activity than others. Inhibition zone diameter reached 20–25 mm in E. coli and S. aureus growth, respectively. TLC assay showed three spots in which two of them confirmed antibacterial activity in the bioautography assay that yielded Rf values of 0.47 for E. coli and 0.72 for S. aureus, while MIC assay showed that the lowest extract concentration inhibited bacterial growth was 20%. KEY WORDS: bioautography assay, Streptomyces, antibacterial activity, Rf value, MIC Corresponding Author: DINI RYANDINI | email: dini_ryandini@yahoo.com INTRODUCTION Actinomycetes are soil-borne microbes capable of producing antibacterial compounds. They are Gram- positive, filamentous, and saprophytic bacteria (Oskay et al., 2004). An example of these microbes is Streptomyces (Thakur, 2011). Antibacterial compounds produced by Streptomyces are streptomycin, aureomycin, chloromycetin, tramycin, erythromycin, and magnamycin. These compounds have varied potentials and specification (Holt et al., 2000). Explorations of Streptomyces have been widely done, due to the high demand for antibacterial compounds, and triggered by the emergence of resistance problems of pathogenic microbes toward antibiotics. The exploration has been done in various environments, even in a unique habitat. Mangrove forest is a possible environment for the source of Streptomyces. It has rich organic substances that very likely to be the source of antibacterial producing actinomycetes (Alanis, 2005). Mangrove forest of Segara Anakan, Cilacap, is an intertidal zone influenced by the sea tidal waves. According to Suryono (2006), various mangrove species grew according to zonation, the distance from where they grew to the shore. Avicennia marina was a species that grow in the closest distance to sea waters with higher environment salinity compared to other mangrove vegetation (Sukmarani et al., 2008). The explorations of Streptomyces in mangrove area is crucial because this bacteria has a superior ability to survive the intertidal zone, thus considered to have some specific potential related to primary and secondary metabolite productions (Sathya and Ushadevi, 2009). The assay of antibacterial activity could be done with diffusion and dilution method towards Gram- negative bacteria, Escherichia coli, and Gram-positive bacteria, Staphylococcus aureus. The species have different cell wall structure located on the peptidoglycan layer. Thus, different responses toward antibacterial compounds were expected. The mechanisms of microorganism growth inhibition included cell wall synthesis inhibition, a distraction of cell membrane permeability, and blockage of replication, transcription, and translation of bacterial genetic materials (Oskay, 2004). The advance assay of antibacterial compounds is bioautographic test towards chromatography results, to test the antibacterial ability of antibacterial compounds (Oedjijono et al., 1993; Patil et al.,2013). Based on this review, the objectives of this research were to obtain antibacterial producing Streptomyces isolate from the Avicennia marina rhizosphere, and to examine the antibacterial ability and antibacterial compounds characters produced. METHOD The samples were A. marina rhizosphere soils of site E46 and E40 Segara Anakan, Cilacap. Streptomyces was isolated with pour plate method on solid medium, Starch Casein Agar (SCN), and incubated at room temperature for 5–7 days. The isolates were then characterized morphologically and biochemically according to Holt et al. (2000). Screening and selection of antibacterial producing isolates were done by diffusion method in Nutrient Agar (NA) medium. The isolates were incubated in liquid SCN medium. After eight days, the cultures were filtered through Whatman paper. The filtrate of 15 µl volume was dropped on a paper disc 6 mm, and placed on spread cultures of E. coli and S. aureus. The cultures were incubated for 24–48 hours at a temperature of 37°C. Parameters that evaluated were Φ of inhibition zone. Streptomyces producing the widest inhibition was selected for the next assay.