Disease control is critical for effective hatchery production of bivalve shellfish. Bacterial infections, particularly those associated with Vibrio and Aeromonas , cause rapid larval mortality, with severe consequences for hatcheries and farmers who rely on them. This study aims to screen and identify potentially pathogenic and probiotic bacteria in bivalve shellfish facilities.
A total of 122 bacterial isolates from water, algae, and larval samples were identified using 16S rRNA sequencing and screened for their antimicrobial activity against shellfish pathogens , hemolytic activity, and biofilm formation. Among the 20 genera identified, Vibrio (34%) , Pseudoalteromonas (23%) , and Alteromonas (18%) are the most abundant.
The pathogenicity of the selected potential pathogenic and probiotic isolates was tested with oysters and clam larvae, and adult oyster hemocytes. Results showed that potential probiotic isolates are generally safe while some potential pathogens (Clam15, DEN12, CH1, CH7, CH3, CH30, CH4, CH6) showed host-specific pathogenicity to either clam or oyster larvae. Results from the high-throughput screening assay using oyster hemocytes were concordant with the results of the more labor-intensive larval assays. Further work is being done to optimize the high-throughput screening pipeline.