title: Effects of laser irradiation on a bloom forming cyanobacterium Microcystis aeruginosa.
abstract: Effects of laser irradiation on photosystem II (PS II) photochemical efficiencies, growth, and other physiological responses of Microcystis aeruginosa were investigated in this study. Results indicate that laser irradiation (wavelengths 405, 450, 532, and 650 nm) could effectively inhibit maximal PS II quantum yield (Fv/Fm) and maximal electron transport rates (ETRmax) of M. aeruginosa, while saturating light levels (Ek) of M. aeruginosa did not change significantly. Among the four tested wavelengths, 650 nm laser (red light) showed the highest inhibitory efficiency. Following 650 nm laser irradiation, the growth of M. aeruginosa was significantly suppressed, and contents of cellular photosynthetic pigments (chlorophyll a, carotenoid, phycocyanin, and allophycocyanin) decreased as irradiation dose increased. Meanwhile, laser irradiation enhanced the enzyme activities of superoxide dismutase (SOD) and peroxidase (POD) in M. aeruginosa cells. Lower irradiation doses did not change the intracellular microcystin contents, but higher dose irradiation (>1284 J cm-2) caused the release of microcystin into the culture medium. Transmission electron microscope examination showed that the ultrastructure of M. aeruginosa cells was destructed progressively following laser irradiation. Effects of laser irradiation on M. aeruginosa may be a combination of photochemical, electromagnetic, and thermal effects.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road #7, Wuhan, 43001284, People's Republic of China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Tiancui
authors.initials: T
authors.lastname: Li
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Bi
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road #7, Wuhan, 43001284, People's Republic of China.
authors.forename: Jiantong
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road #7, Wuhan, 43001284, People's Republic of China. chenxi.wu@ihb.ac.cn.
authors.forename: Chenxi
authors.initials: C
authors.lastname: Wu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport; D005068:Eutrophication / Q000528:radiation effects*; D052998:Microcystins / Q000378:metabolism; D046931:Microcystis / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D052998:Microcystins; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D002338:Carotenoids; C078588:microcystin; D013482:Superoxide Dismutase
keywords: Antioxidant enzyme; Growth inhibition; Laser irradiation; Microcystin; Microcystis aeruginosa; Photosynthetic activity