title: The effects of sub-lethal UV-C irradiation on growth and cell integrity of cyanobacteria and green algae.
abstract: The effects of UV-C irradiation on algal growth and cell integrity were investigated to develop a potential method for preventing cyanobacterial blooms. The toxic cyanobacterium Microcystis aeruginosa and three common freshwater green algae Chlorella ellipsoidea, Chlorella vulgaris, and Scenedesmus quadricanda were exposed to UV-C irradiation at 0-200mJcm(-2) and subsequently incubated for 9-15 d under normal culture conditions. Cell density and cell integrity were assessed using flow cytometry. The results suggested that UV-C irradiation at 20-200mJcm(-2) can suppress M. aeruginosa growth for 3-13 d in a dose-dependent manner. UV-C irradiation at 20 and 50mJcm(-2) is sub-lethal to M. aeruginosa cells as over 80% of the exposed cells remained intact. However, UV-C irradiation at 100 and 200mJcm(-2) induced severe cell disintegration in more than 70% of the irradiated cells. Neither significant suppression nor disintegration effects on green algae were observed for UV-C irradiation at 20-200mJcm(-2) in this study. Taken together, the sensitivity of M. aeruginosa to UV-C irradiation was significantly higher than that of the non-toxic C. ellipsoidea, C. vulgaris, and S. quadricauda, suggesting the potential application of sub-lethal UV-C irradiation for M. aeruginosa bloom control with a predictable low ecological risk.
authors.affiliation: Research Center for Environmental Engineering and Management, Tsinghua University, Shenzhen, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Tao
authors.forename: Xihui
authors.initials: X
authors.lastname: Zhang
authors.forename: Doris W T
authors.initials: DW
authors.lastname: Au
authors.forename: Xianzhong
authors.initials: X
authors.lastname: Mao
authors.forename: Kan
authors.initials: K
authors.lastname: Yuan
mesh_terms: D000460:Chlorophyta / Q000254:growth & development* / Q000528:radiation effects; D000458:Cyanobacteria / Q000254:growth & development* / Q000528:radiation effects; D005434:Flow Cytometry; D014466:Ultraviolet Rays; D018508:Water Purification