We describe the isolation of strain JA and demonstrate that this bacterium exhibited strong algicidal effects on the algae with an inhibition rate exceeding 80 % within 48 h JA significantly reduced the photosynthetic efficiency of and caused extensive morphological damage to the algae. Genomic analysis of JA demonstrated that a putative AI-2 type quorum sensing (QS) gene () is present in its genome cluster, which is regulate pheromone biosynthesis. Interestingly, the exogenous addition of a QS-oligopeptide (ComX-pheromone) improved the algicidal efficiency of JA, thus indicating that the algicidal activity of this bacterium is potentially regulated by QS. Collectively, our data describe a potential antialgal bacterium and speculated that its behavior can be modulated by QS signal. JA may therefore represent a valuable tool for the development of novel chemical-ecological methods with which to control harmful algae.