Inactivation of Microcystis aeruginosa by hydrogen-terminated porous Si wafer: Performance and mechanisms

We proposed a method to inactivate Microcystis aeruginosa by using hydrogen-terminated porous Si (H-PSi) wafer. The influences of oxidation time on the removal of M. aeruginosa were investigated. Samples oxidized by H-PSi wafer were subsequently grown under illuminated culture conditions. The results demonstrated that the optimal oxidation time was about 1 h, which could control the growth of M. aeruginosa about 65%, after 3 days culture. Simultaneously, extracellular microcystins was decreased from 14.65 to 7.06 mu g L-1 and remain relative integrity of M. aeruginosa cells which could avoid secretion of large amounts of organic material. Multiple analysis techniques including fluorescence excitation-emission matrix (EEM) and fluorescence microscope were used to reveal the inhibition mechanisms of M. aeruginosa. Meanwhile, analyses of reactive oxygen level, malondialdehyde content, and superoxide dismutase activity indicated that the damage and inactivate of M. aeruginosa cells are mainly due to accumulation of lipid peroxidation and inhibition of normal physiological metabolism by free radicals produced by H-PSi wafer under visible light irradiation. In conclusion, these results suggest that H-PSi wafer may be useful in controlling growth and survival of M. aeruginosa in many large lakes and reservoirs, thus mitigating many of the economic, esthetic ecological impacts of the invasive alga. (C) 2016 Elsevier B.V. All rights reserved.