Isolation and characterization of Noctiluca-killing bacteria from a shrimp aquaculture pond in Thailand

To control harmful algal blooms (HABs), in particular dinoflagellate Noctiluca scintillans, which causes damage to shrimp production, algicidal bacteria were isolated from shrimp pond water and screened for their killing effect against N. scintillans under laboratory condition. Among 260 bacterial isolates, 10 showed killing effects on N. scintillans. Out of 5 strains showing relatively stronger killing activity, 4 strains belonged to the Gammaproteobacteria group. Among these, strain BS2 (identified as Marinobacteria salsuginis) showed the strongest Noctiluca-killing activity. In the present study, we also investigated bacterial effects against growth of other phytoplankton species. Strain BS2 killed only N. scintillans but not any other phytoplankton (Heterosigma akashiwo NIES-6, Chatonella antique NIES-1, Chaetoceros ceratosporum, Prorocentrum lima, and Dunaliella sp.). Results of the present study lead us to expect prevention of damage by HABs, in particular dinoflagellate N. scintillans, in shrimp farming and mitigation for shrimp production in ponds using Noctiluca-killing bacteria.