Development of alternative in situ treatments for stony coral tissue loss disease

The only current in situ treatment for SCTLD is an antibiotic-based paste which risks selecting for antibiotic-resistant pathogens and harming beneficial microflora on the coral animal. The application of beneficial microorganisms (i.e., probiotics) offers an alternative treatment option that does not hold the same risks as antibiotics. This project used optimized workflows to find significantly more potential probiotic candidates for SCTLD treatment. Libraries of microbial isolates across coral species were isolated and screened for inhibitory activity against SCTLD-associated target strains using newly developed high-throughput methods. A new culturing medium was developed to select for a greater diversity of strains. Further modifications to culturing conditions also showed that promising isolates are likely using antimicrobial inhibition. Pairwise combinations of isolates with the known coral probiotic McH1-7 also revealed that combinatory treatments did not increase inhibition towards SCTLD-associated target strains. Given these findings, future work will focus on continuing to screen for promising probiotic candidates.