Abstract

Toxic Microcystis aeruginosa blooms have been increased in freshwater body in China in recent years. The discovery of algicidal bacteria has brought renewed attention in the treatment of the harmful algae blooms (HABs). In this study, one strain of algicidal bacterium number SDK2 was selected from a eutrophic lake and its inhibition effects on M. aeruginosa and microcystin-LR released by M. aeruginosawas studied. The algicidal activity showed that the strain SDK2 had significant algicidal efficiency on M. aeruginosa. The removal rate of chlorophyll a increased when the bacterial cell density increased and it reached a maximum of 80%. It inhibited M. aeruginosa indirectly by releasing extracellular algicidal matter. It also had good degradation effects on microcystin-LR and the removal rate was 65%. According to the physiological and biochemical characteristics and the16S rDNA sequencing analysis of the strain SDK2, it was identified as Ochrobactrum sp.

Key words: Removal, Microcystis aeruginosa, microsystins, algicidal bacterium.