A noteworthy response process of Microcystis aeruginosa induced by exogenous reactive oxygen species in algae-laden water treatment

Abstract

The effectiveness of reactive oxygen species (ROS) generated by advanced oxidation processes (AOPs) in inactivating harmful algae in drinking water varies considerably. Therefore, the physiological and biochemical reactions of algae need to be considered to clarify the underlying mechanisms. Herein, we studied the response mechanisms of Microcystis aeruginosa to exogenous ROS. Increased CAT, SOD, and GSH levels indicated oxidative stress damage, and increased MDA levels indicated lipid peroxidation in the treatment group. SEM images and fluorescence spectrogram revealed that these reactions promote the release of extracellular polymeric substances (EPS), which increase by ≥ 1.2 mg/L for proteins and ≥ 0.89 mg/L for polysaccharides. The phycobiliprotein content decreased, in which phycocyanin content decreased by approximately 77.41 %. Changes in differential metabolites, including increased regulation of protein and polysaccharide synthesis, enhanced cell membrane fluidity, and increased intracellular microcystin-LR levels were significantly associated with these results. Increased alkaloid levels, reduced vitamin levels, and ATP imbalances also affect cellular activity. These results provide new insights into the response mechanisms of algae and facilitate the practical and sustainable applications of AOPs-treated algae-laden water.