Identification and Algae-Lytic Characteristics of a Pigment-Generating Bacterium Isolated from Lake TaiHu

An algicidal bacterium was isolated from Lake Taihu during the bloom of Microcystis in 2009. It was Gram-negative, oxidase-negative, and produced red-colored colonies on agar media. The strain was tentatively identified as Serratia marcescens by means of physiological, biochemical reactions and homology analysis based on 16S rDNA. The bacteria could degrade Microcystis aeruginosa effectively. When the algae density was 5.9×10⁶ cells/mL and bacterial cell densities were 9.1×10⁸, 9.1×10⁷ and 9.1×10⁶ cells/mL, the algae-lytic activity was 95%, 81% and 75% in 48h treatment, respectively. The extracellular substance of a kind of pigment produced by the bacteria might be related to algae-lytic effect. The bacterial cell or intracellular substances could also play a certain role in the algae-lysing process.