title: Effects of iron on growth, pigment content, photosystem II efficiency, and siderophores production of Microcystis aeruginosa and Microcystis wesenbergii.
abstract: Changes in growth, photosynthetic pigments, and photosystem II (PS II) photochemical efficiency as well as production of siderophores of Microcystis aeruginosa and Microcystis wesenbergii were determined in this experiment. Results showed growths of M. aeruginosa and M. wesenbergii, measured by means of optical density at 665 nm, were severely inhibited under an iron-limited condition, whereas they thrived under an iron-replete condition. The contents of chlorophyll-a, carotenoid, phycocyanin, and allophycocyanin under an iron-limited condition were lower than those under an iron-replete condition, and they all reached maximal contents on day 4 under the iron-limited condition. PS II photochemical efficiencies (maximal PS II quantum yield), saturating light levels (I(k)) and maximal electron transport rates (ETR(max)) of M. aeruginosa and M. wesenbergii declined sharply under the iron-limited condition. The PS II photochemical efficiency and ETR(max) of M. aeruginosa rose , whereas in the strain of M. wesenbergii, they declined gradually under the iron-replete condition. In addition, I ( k ) of M. aeruginosa and M. wesenbergii under the iron-replete condition did not change obviously. Siderophore production of M. aeruginosa was higher than that of M. wesenbergii under the iron-limited condition. It was concluded that M. aeruginosa requires higher iron concentration for physiological and biochemical processes compared with M. wesenbergii, but its tolerance against too high a concentration of iron is weaker than M. wesenbergii.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Xing
authors.forename: Wen-min
authors.initials: WM
authors.lastname: Huang
authors.forename: Dun-hai
authors.initials: DH
authors.lastname: Li
authors.forename: Yong-ding
authors.initials: YD
authors.lastname: Liu
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D007501:Iron / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D046931:Microcystis / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000187:drug effects* / Q000378:metabolism; D010860:Pigments, Biological / Q000378:metabolism*; D017262:Siderophores / Q000096:biosynthesis*; D013045:Species Specificity
chemical_list: D045332:Photosystem II Protein Complex; D010860:Pigments, Biological; D017262:Siderophores; D002734:Chlorophyll; D007501:Iron; D000077194:Chlorophyll A