Bacteria associated with healthy and white syndrome diseased Acropora collected from Gili Labak Island Sumenep and their antibacterial activity

Abstract

Gili Labak has an excellent coral reef condition but has many problems, including coral disease. This study aims to identify bacteria that are associated with Acropora Formosa corals, which have the potential as antibacterial white plague disease in Acropora sp. The method used in the antibacterial test is the overlay test and agar diffusion test and laboratory analysis using bacterial isolation, DNA extraction, DNA amplification, sequencing, and phylogenetic analysis. Based on bacteria morphology, four bacterial isolates were found from healthy Acropora, namely AF1, AF2, AF3, and AF4. From the results of the antibacterial activity test using the pathogenic bacterium Bacillus Firmus, isolates AF1 produced an inhibitory zone in three days of 5.10 ± 0.10 mm, 2.7 ± 0.04 mm, and 3.80 ± 0.02 mm, respectively, while AF3 produced an inhibitory zone of 2.90 ± 0.16 mm, 3.10 ± 0.06 mm, and 2.7 ± 0.11 mm, respectively. Meanwhile, the antibacterial activity test using pathogenic bacteria Bacillus dretensis, AF2 produced an inhibitory zone of 3.80 ± 0.01 mm, 2.20 ± 0.15 mm, and 1.30 ± 0.09 mm, respectively, while AF4 produced an inhibitory zone of 4.60 ± 0.060 mm, 2.90 ± 0.06 mm, and 1,00 ± 0.06 mm, respectively. The results showed that all isolate from healthy Acropora formosa had potential antibacterial activity against bacteria of white plague disease. The phylogenetic analysis showed that AF1, AF3, and AF4 had 99% similarity with Virgibacillus salarius, and AF2 had 98% similarity with Halomonas sp.