AACL Bioflux, vol: 13,6 (2020)
Antibacterial potential of hard coral-associated bacteria against human pathogenic multidrug resistant bacteria
Ayuningrum D., Muchlissin S.I., Sabdono A., Trianto A., Radjasa O.K.
Abstract
Hard corals are sources of a wide variety of natural compounds with anticancer, anti-inflammatory, antivirus, anti-tumor, and anti-microbial pharmacological properties. This discovery and their consequential extraction to obtain bioactive compounds has led to the overexploitation of reefs, resulting in damaged coral and imbalances in coral reef ecosystems. Hard coral-associated bacteria have been proven to contain compounds similar to their hosts. The purpose of this research was to isolate and purify hard coral-associated bacteria, to estimate the potential of their antibacterial activity against human-pathogenic multidrug resistant (MDR) bacteria, and finally to generate a crude extract from the most effective bacterial strains against human-pathogenic MDR bacteria and test it. The sampling of hard corals for this study took place in Panjang Island and Awur Bay, North Java Sea, Indonesia, using purposive sampling methods. Isolation and purification of hard coral-associated bacteria were conducted with serial dilution and streak plate methods on pepton yeast agar media. Screening and confirmation of antibacterial activity were done with the overlay and agar plug method. Furthermore, the most effective bacterial strain was cultivated in liquid medium and extracted using liquid-liquid extraction. Antibacterial assay from crude extract was conducted using the agar disk diffusion method. A total of 32 bacterial-isolates from 7 hard coral genera were obtained: Acropora, Caulastrea, Favia, Favites, Goniastrea, Isopora, and Pachyseris. 41% of the obtained bacteria were active against human-pathogenic MDR bacteria Acinetobacter baumannii, Enterobacter aerogenes, Enterobacter cloacae, Klebsiella pneumonia, methicillin-resistant Staphylococcus aures (MRSA), Pseudomonas aeruginosa, and Staphylococcus haemolythicus. Most of the active bacterial strains were from hard coral genera Caulastrea, Favia, Favites, and Goniastrea. Confirmation of the antibacterial activity showed the strongest antibacterial activity against human-pathogenic MDR E. aerogenes in two bacterial strains (PHC 43/01 and PHC 49/08) with a zone of inhibition (ZOI) of 25.88±3.23 mm and 21.18±0.17 mm, respectively. The extraction resulted in supernatant and pellet crude extract, but only supernatant crude extract indicated an antibacterial activity against MDR A. baumannii, while the pellet did not. The best concentration level for antibacterial activity was 90 g mL-1, with a ZOI diameter of 11.43±0.85 mm. © 2020, BIOFLUX SRL. All rights reserved.
Keyword: Acinetobacter baumannii; Acropora; Crude extract; Panjang Island; Symbiont