Antibacterial Activity of Carotenoid from Bacterial Symbiont of the Soft Coral Sinularia sp. against MDR and MRSA Bacteria

This study aimed to isolate and identify the soft coral symbiotic bacteria Sinularia sp. which has activity against pathogenic bacteria MDR (Escherichia coli and Staphylococcus aureus) and MRSA (methicillin-resistant Staphylococcus aureus). Symbiotic bacteria isolated from soft coral Sinularia sp. were collected from the waters of Panjang Island, Jepara, Central Java, Indonesia for antimicrobial activity. Carotenoid-containing bacteria were tested for antibacterial activity against various pathogenic bacteria, including MDR Escherichia coli, MDR Staphylococcus aureus, and MRSA, and identifying antibiotic producers which is potential. The carotenoid extracts obtained were identified by UV-Vis spectrophotometer. The results showed that the P.Si 1 isolate was a symbiotic bacterial from Sinularia sp. containing carotenoids. The molecular identification based on 16S rDNA showed that the most closely related species with P.Si 1 was Acinetobacter vivianii with only 80% of sequence identity. The results of the screening test showed that the average clear zone diameter for MDR E. coli antibacterial test at 2% concentration was 1.243cm, at 3% was 1.476cm, and at 4% it was 1.765cm, with a positive control of 2.325cm. The results of the antibacterial test against MDR S.aureus recorded average diameters at concentrations of 2% (1.534cm), 3% (1.678cm), 4% (1.885cm), with positive control of 2.543cm. In addition, the antibacterial test against MRSA showed average diameters at concentrations of 2% (1.757cm), 3% (1.944cm), and 4% (2.247cm), with positive control of 2.471cm. Remarkably, carotenoids in A. vivianii have antibacterial activity.