Simultaneous photoinactivation of Microcystis aeruginosa and photocatalytic degradation of microcystin-LR by erythrosine-based photosensitizer

The simultaneous control of toxic cyanobacterial blooms and degradation of microcystins (MCs) remains a critical challenge for environmental risk reduction. Herein, we demonstrate the novel application of erythrosine (ERY), an FDA-certified food additive, as a potent photoactive agent for concurrent control of cyanobacterial blooms and removal of microcystin-LR (MC-LR) contaminants. ERY treatment achieved effective growth inhibition of Microcystis aeruginosa . Mechanistic studies revealed that ERY-generated including reactive oxygen species (ROS) severely damaged cellular structures and photosynthesis systems. Notably, ERY-treated samples showed a significantly greater reduction in extracellular MC-LR content compared to conventional H 2 O 2 treatment, confirming its superior microcystin degradation efficiency. The degradation products of MC-LR were elucidated through LC-MS/MS analysis, and degradation pathways and reactive sites were verified by theoretical calculations. Furthermore, ecotoxicological evaluation using Lemna minor and rapid photodegradation of ERY (95.6% within 4 days) confirmed its minimal phytotoxicity and the risk from the parent MC‑LR is eliminated, but the potential hazard of transient intermediates requires further study. These findings position ERY as a promising and environmentally benign photosensitizer for harmful algal bloom mitigation.