title: Effects of iron on growth, antioxidant enzyme activity, bound extracellular polymeric substances and microcystin production of Microcystis aeruginosa FACHB-905.
abstract: Toxic cyanobacterial blooms have occurred in various water bodies during recent decades and made serious health hazards to plants, animals and humans. Iron is an important micronutrient for algal growth and recently, the concentration of which has increased remarkably in freshwaters. In this paper, the cyanobacterium Microcystis aeruginosa FACHB-905 was cultivated under non-iron (0μM), iron-limited (10μM) and iron-replete (100μM) conditions to investigate the effects of iron on growth, antioxidant enzyme activity, EPS and microcystin production. The results showed that algal cell density and chlorophyll-a content were maximal at the highest iron concentration. Antioxidant enzymes activity increased notably under all three conditions in the early stage of experiment, of which the SOD activity recovered soon from oxidative stress in 10μM group. The productions of some protein-like substances and humic acid-like substances of bound EPS were inhibited in iron-containing groups in the early stage of experiment while promoted after the adaptation period of Microcystis aeruginosa. Iron addition is a factor affecting the formation of cyanobacterial blooms through its impact on the content of LB-EPS and the composition of TB-EPS. The intracellular MC-LR concentration and the productivity potential of MC-LR were the lowest in 0μM group and highest in 10μM group. No obvious extracellular release of MC-LR was observed during the cultivation time. Therefore, iron addition can promote the physiological activities of M. aeruginosa, but a greater harm could be brought into environment under iron-limited (10μM) condition than under iron-replete (100μM) condition.
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China.
authors.forename: Xun
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China. Electronic address: pfwang2005@hhu.edu.cn.
authors.forename: Peifang
authors.initials: P
authors.lastname: Wang
authors.affiliation: School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Hou
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Qian
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D005618:Fresh Water; D006812:Humic Substances / Q000032:analysis; D007501:Iron / Q000378:metabolism / Q000494:pharmacology*; D052998:Microcystins / Q000096:biosynthesis*; D046931:Microcystis / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D010084:Oxidation-Reduction; D011108:Polymers / Q000032:analysis* / Q000378:metabolism; D014131:Trace Elements / Q000378:metabolism
chemical_list: D000975:Antioxidants; D006812:Humic Substances; D052998:Microcystins; D011108:Polymers; D014131:Trace Elements; D002734:Chlorophyll; C078588:microcystin; D007501:Iron; D000077194:Chlorophyll A
keywords: Algal growth; Extracellular polymeric substances; Iron; Microcystin production; Microcystis aeruginosa; Oxidative stress