Isolation, Identification and Characterization of Blue-green Algae-lysing Strain DC-L14 from Lake Dianchi, China

Abstract

An algae-lysing strain DC-L14 was isolated from an area with dense blue-green algae in Lake Dianchi, southwestern China and it was identified as Lysinibacillus fusiformis based on 16S rDNA sequence analysis. The toxicity test on mouse primarily showed that the strain was non-toxic. Under the laboratory condition, the strain could cause Microcystis aeruginosa cells to agglomerate, sinking to bottom and becoming yellow. The reduction rate of chlorophyll a after 4 days was 67.2% on an average, with the highest of 70.1% and lowest of 65.5% in the cultures of Microcystis viridis, M wesenbergii, Aphanizomenon flos-aquae and Anubaena flos-aquae. The strongest algae-lytic ability was found at the stable phase of DC-L14 culture, which could reduce chlorophyll a content of M aeruginosa by 82.1% in four days. After centrifugation and sedimentation, the cells of bacteria showed no algae-lytic ability, but the cell-free supernatant displayed the same algae-lytic ability as that of the whole bacteria culture, and the heated bacterial culture showed the highest algae-lytic ability, indicating that some extracellular and thermo-stable substances produced by this strain had the algae-lytic ability, and high temperature possibly reinforced the algae-lytic ability