Screening of Antibacterial Compound and Detection of Polyketide Synthetase - Non Ribosomal Peptide Synthetase (PKS-NRPS) Biosynthetic Gene from Tunicates-Associated Bacteria Collected from The Kumbang Shipwreck (Karimunjawa, Indonesia)

The presence of bacteria resistant to various types of antibiotics referred to as MDR (Multi Drugs Resistant) bacteria has driven the exploration of bioactive compounds as new antibiotic candidates. Tunicates-associated bacteria have been reported to have the potential to produce bioactive compounds that can fight MDR bacteria. This study aims to isolate and analyze the number of colonies of tunicate-associated bacteria on different media, analyze the antibacterial activity of isolates against MDR bacteria, find potential tunicate-associated bacterial species in inhibiting MDR bacteria, and detect PKS-1 and NRPS genes from potential isolates. The methods used were isolation of associated bacteria by multistage dilution method, screening of antibacterial activity using agar plug method, amplification of 16S rRNA, PKS-1 and NRPS genes using Polymerase Chain Reaction (PCR) method, and species identification by 16S rRNA gene sequencing then analyzed using Basic Local Alignment Search Tool (BLAST). The results were obtained tunicates from the Genera Polycitorella, Plebobranchia, Rhopalaea, Clavelina, and Didemnum. Pure isolates that were successfully isolated from the 6 tunicates were 12 isolates from Zobell 2216 media and 69 isolates from M1 media. Potential isolates obtained include isolate KM402-02 which is Klebsiella variicola (homology 99.20%) able to inhibit S. aureus (3.3 mm), E. coli (5.8 mm) and P. aeruginosa (4.6 mm), isolate KJ2Z411-04 is Vibrio alginolytiicus (homology 99.86%) able to inhibit S. aureus (10 mm) and E. coli (8.4 mm), and isolate KJ2Z318-01 is Bacillus paramycoides (homology 99.86%) able to inhibit S. aureus (7.8 mm) and E. coli (4.1 mm). Isolation using M1 media showed better results on the growth of tunicates association bacteria. This study succeeded in identifying 3 potential bacteria as anti-MDR. PKS-1 gene was detected in Klebsiella variicola and Vibrio alginolytiicus. HIGHLIGHTS Tunicates from the Genera Polycitorella, Plebobranchia, Rhopalaea, Clavelina, and Didemnum can be used as inoculum sources to produce bacterial isolates that have antibacterial properties. Pure isolates that were successfully isolated from the 6 tunicates were 12 isolates from Zobell 2216 media and 69 isolates from M1 (M1 medium for marine bacteria). Potential isolates obtained include isolate KM402-02 which is Klebsiella variicola (homology 99.20%) able to inhibit MDR aureus (3.3 mm), E. coli (5.8 mm) and P. aeruginosa (4.6 mm). Isolate KJ2Z411-04 is Vibrio alginolytiicus (homology 99.86%) able to inhibit MDR aureus (10 mm) and E. coli (8.4 mm) Isolate KJ2Z318-01 is Bacillus paramycoides (homology 99.86%) able to inhibit MDR aureus (7.8 mm) and E. coli (4.1 mm). PKS-1 gene was detected in Klebsiella variicola and Vibrio alginolytiicus. GRAPHICAL ABSTRACT