Growth inhibition of Microcystis aeruginosa by white-rot fungus Lopharia spadicea

Harmful cyanobacterial blooms cause water deterioration and threaten human health. It is necessary to remove harmful cyanobacteria with useful methods. A bio-treatment may be one of the best ways to do this. A strain of specific white-rot fungus, Lopharia spadicea, with algicidal ability was isolated. Its algicidal ability on algae under various conditions was determined using three main influence factors: initial chlorophyll-a content, initial pH, and algal cell mixture. The result showed that the chlorophyll-a content of Microcystis aeruginosa FACHB-912, Oocystis borgei FACHB-1108, and Microcystis flos-aquae FACHB-1028 decreased from 798 +/- 13, 756 +/- 40, and 773 +/- 24 mu g/L to 0 within 39 h. L. spadicea could also remove more than 95% chlorophyll-a when initial chlorophyll-a content increased from 397 +/- 13 to 2,132 +/- 4 mu/L. Moreover, the strain has great removal ability under a broad initial pH range of 5.5 to 9.5. The chlorophyll-a content of the three algal strain mixtures decreased from about 672 +/- 23 mu g/L to 0 within 45h. After superoxide dismutase (SOD) and malondialdehyde (MAD) were assessed in a co-culture of L. spadicea, it was observed that an increase in MAD content was correlated with the decrease in chlorophyll-a content of M. aeruginosa FACHB-912. This result suggested that the algae was not only greatly inhibited but also severely damaged by the fungus.