Low- or Medium-pressure UV Lamp Inactivation of Microcystis aeruginosa

Abstract

A pure culture of Microcystis aeruginosa (NIES-98) was exposed to low-pressure (LP) or medium-pressure (MP) UV lamps and subsequently incubated under white light fluorescent lamps allowing both photoreactivation and photosynthesis. During incubation, profiles of the number of existing cells and UV-induced DNA damage were determined for each sample.The growth of Microcystis aeruginosa was inhibited by the exposure to LPUV or MPUV. Only a minor difference was observed between LPUV and MPUV both in the cell number and the DNA damage.UV-induced DNA damage just after UV irradiation was almost the same regardless of the UV fluence or the UV lamp. Meanwhile, the UV-induced DNA damage was repaired during 1day incubation after UV exposure, and the number of DNA damage appeared somehow proportional to the UV fluence after 1day incubation.A comparison between the cell number and the number of DNA damage implied that the UV-induced DNA damage mainly contributed to the cell number reduction of Microcystis aeruginosa.