Pathogenicity of Aeromonas hydrophila isolated from the Malaysian Sea against coral (Turbinaria sp.) and sea bass (Lates calcarifer)

A study was carried out to determine the pathogenicity (hemolytic activity) on corals (Turbinaria sp.) and sea bass (Lates calcarifer) of Aeromonas hydrophila from water, sediment, and coral. Samples were collected from coastal water and coral reef areas. One hundred and sixty-two isolates were successfully isolated. Out of 162, 95 were from seawater, 49 from sediment, and 18 from coral. Sixteen isolates were picked and identified. Isolates were identified using a conventional biochemical test, the API 20NE kit, and 16S rRNA nucleotide sequences. Hemolytic activity was determined. Out of 16 isolates, 14 isolates were beta-hemolytic and two isolates were non-hemolytic. Corals infected with A. hydrophila suffered bleaching. Similar effect was observed for both hemolytic and non-hemolytic isolates. Intramuscular injection of A. hydrophila into sea bass resulted in muscular bleeding and death. Higher infection rates were obtained from hemolytic compared to non-hemolytic strains of A. hydrophila isolates.