An efficient screening approach for anti-Microcystis compounds based on knowledge of aquatic microbial ecosystem

To improve the efficiency of screening for anti-Microcystis compounds, we p lanned to use algae-lysing bacteria that kill the organisms of water blooms . A two step-screening process was carried out, i.e., the screening of alga e-lysing bacteria and the selection of anti-Microcystis producers from the bacteria. Sources for the isolation of the bacteria were a co-cultivated fl uid of a water sample with axenie Microcystis viridis, a water sample colle cted in a water bloom season, and a water bloom sample. The water bloom sam ple was the best source for the isolation of the algae-lysing bacteria and such bacteria were shown to exhibit potent activity. Seventeen strains out of 20 isolated algae-lysing bacteria produced anti-Microcystis activities, and one of the principles was the previously reported argimicin A. These re sults indicate that algae-lysing bacteria in water blooms may be good sourc es for potent and selective anti-cyanobacterial compounds.