Potential of antagonistic activity from associated bacteria from healthy and bleaching acropora corals of Blitar Waters, East Java, Indonesia

Laboratory of Microbiology, Department of Marine Science and Technology, Faculty of Fisheries and Marine Sciences, IPB University, Indonesia

Abstract

Global warming leads to high coral bleaching phenomena in marine ecosystems. The bleach condition of corals can cause a disease that is enhanced by opportunistic or pathogenic microorganisms. This research aimed to investigate the antagonistic interactions between healthy and bleached coral-associated bacteria. Isolation of coral-associated bacteria was carried out using the spread plate method in half-strength Zobell 2216E medium. Antagonistic activity was observed using a double-layer method, with each layer of medium inoculated with healthy or bleached coral-associated bacteria. The interactions between healthy and bleached coral isolates were analyzed using correspondence analysis. Twenty healthy and 11 bleached coral isolates were found in the six coral samples. Approximately 14 bacterial isolates from healthy corals demonstrated antagonistic (inhibitory) activity against 11 bacterial isolates from bleaching coral samples, with isolate AcD.14 from bleached coral, inhibited by 57.14% of the active isolates from healthy corals. Correspondence analysis resulted in isolate AcD.16, a bleaching coral bacterium with sufficient pathogenicity to elicit an antagonistic response from healthy coral bacteria. This study showed that there is high potential for finding bio-control agents for coral diseases using their natural microbiomes from healthy corals.