Algicidal activity of Streptomyces sp. LMJ-114 against Microcystis aeruginosa

Mijia Du¹Qian Xie¹Hongqiu Shi^1*Jianyuan Yang¹Qigen Guo¹Yuqin Zhang^2*Binghuo Zhang^1*

• ¹Jiujiang University, Jiujiang, China
• ²China Academy of Chinese Medical Sciences, Beijing, China

An actinomycete strain, designated as LMJ-114, capable of eliminating cyanobacteria, was isolated from a soil sample collected from Lushan Mountains of China. Strain LMJ-114, belonging to Streptomyces, showed the highest similarity to Streptomyces jiujiangensis JXJ 0074T based on the 16S rRNA gene sequences. This strain showed algicidal activities on both Microcystis and filamentous cyanobacteria. The extracellular water-soluble substances exhibited strong algicidal activity on Microcystis aeruginosa FACHB-905. The algicidal components from strain LMJ-114 could induce M. aeruginosa to produce massive reactive oxygen species (ROS), and seriously affected its antioxidant system. Lipid peroxidation, therefore, occurred seriously in cells of M. aeruginosa, which resulted in 91.6-525.2% higher of malondialdehyde (MDA), and disintegration of gelatinous sheaths, and subsequent sunk cell surface and perforation of the cells. The treatments of both culture broth supernatant and mycelia of strain LMJ-114 significantly affected the contents of retinoic acids (RAs) and microcystins (MCs), and 4 days later, RAs eliminated completely, and 7 days later, microcystin RR (MC-RR) decreased by 96.7 and 87.9%, respectively, and microcystin LR (MC-LR) contents decreased by 89.9 and 81.0%, respectively. L-valine was one of the algicidal compounds in the culture broth supernatant of strain LMJ-114. Strain LMJ-114 and its extracellular metabolites showed potential application in controlling cyanobacterial blooms.