Antibacterial Activity and Molecular Identification of Soft Coral Sinularia sp. Symbiont Bacteria from Karimunjawa Island against Skin Pathogens Propionibacterium acnes and Staphylococcus epidermidis

Soft corals can produce bioactive compounds that act as antibacterials. Sinularia sp. is a soft coral that can produce antibacterial compounds. Symbion bacteria are bacteria that can produce bioactive compounds that tend to be the same as their host. The use of symbiont bacteria can be an alternative to exploit the potential of Sinularia sp. without harming marine life. This study aims to determine the antibacterial potential of the symbiont bacteria obtained from the soft coral Sinularia sp. in inhibiting the growth of Propionibacterium acnes and Staphylococcus epidermidis. The antibacterial activity test was carried out by the agar diffusion method using disc paper. Antibacterial activity was indicated by the formation of a clear zone around the disc paper. The results showed that LA7 isolate had the best antibacterial activity with an average clear zone size of 14.6 mm against Staphylococcus epidermidis and 16.6 mm against Propionibacterium acnes. LA7 isolates identified species based on the 16S rRNA gene with primers 27F and 1492R. Based on molecular species support, it was found that LA7 isolate is Bacillus aerius with a homology level of 98.17%.