Wang Chao, Wang Xun, Wang Peifang, Chen Bin, Hou Jun, Qian Jin, Yang Yangyang
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.
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.
Ecotoxicol Environ Saf. 2016 Oct;132:231-9. doi: 10.1016/j.ecoenv.2016.06.010. Epub 2016 Jun 20.
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.
近几十年来,有毒蓝藻水华在各种水体中频繁发生,对植物、动物和人类健康构成了严重威胁。铁是藻类生长所需的一种重要微量营养元素,近年来淡水水体中铁的含量显著增加。本文通过在无铁(0μM)、缺铁(10μM)和铁充足(100μM)条件下培养铜绿微囊藻FACHB-905,研究铁对其生长、抗氧化酶活性、胞外聚合物(EPS)和微囊藻毒素产生的影响。结果表明,在铁浓度最高时,藻细胞密度和叶绿素a含量达到最大值。在实验初期,三种条件下抗氧化酶活性均显著增加,其中10μM组超氧化物歧化酶(SOD)活性能很快从氧化应激中恢复。在实验初期,含铁组中一些类蛋白物质和结合态EPS中腐殖酸类物质的产生受到抑制,而在铜绿微囊藻适应期后则得到促进。铁的添加通过影响松散结合态EPS(LB-EPS)含量和紧密结合态EPS(TB-EPS)组成,成为影响蓝藻水华形成的一个因素。细胞内微囊藻毒素-LR(MC-LR)浓度和MC-LR的产生潜力在0μM组最低,在10μM组最高。在培养期间未观察到明显的MC-LR胞外释放。因此,铁的添加能促进铜绿微囊藻的生理活性,但在缺铁(10μM)条件下对环境造成的危害可能比铁充足(100μM)条件下更大。