钇(Y3+)对缺氮、缺磷胁迫下铜绿微囊藻生长和生理特性及藻毒素释放的影响

为探究稀土元素钇(Y~(3+))对缺氮、缺磷胁迫下铜绿微囊藻生长的影响,测定了缺素胁迫下不同Y~(3+)浓度时藻的生长量、叶绿素a、可溶性糖、可溶性蛋白含量、抗氧化酶活性(超氧化物歧化酶SOD、过氧化氢酶CAT、过氧化物酶POD)以及丙二醛(MDA)和藻毒素(MC-LR)含量。结果表明:在缺氮、缺磷胁迫下,Y~(3+)对铜绿微囊藻的生长表现出低促高抑的"Hormesis"现象。低浓度Y~(3+)(0.10~0.20 mg·L~(-1))能维持铜绿微囊藻的生长,增强抗氧化酶活性,减轻缺素胁迫造成的损伤;高浓度Y~(3+)(0.50~2.00 mg·L~(-1))则加剧缺氮、缺磷胁迫对藻的迫害,光合色素、可溶性糖及可溶性蛋白含量呈明显的下降趋势,抗氧化酶活性受到抑制,膜质过氧化程度加重,MC-LR含量增加。

Effects of yttrium on growth and physiological characteristics and microcystin release of Microcystis aeruginosa under nitrogen and phosphorus deficiency

Yttrium is a rare earth heavy metal element which has been gradually considered as an important metal pollutant because of its serious adverse effects on aquatic ecosystems. Under the condition of nitrogen and phosphorus deficiency, the growth and metabolism of algae are slow. In order to explore the effects of Y³⁺ on growth and physiological characteristics and microcystin release of Microcystis aeruginosa under nitrogen and phosphorus deficiency, we measured the growth curves of Microcystis aeruginosa and the contents of chlorophyll a, soluble sugar, soluble protein, microcystin-LR; the activity of antioxidant enzymessuperoxide dismutase(SOD), catalase(CAT), peroxidase(POD), and malondialdehyde(MDA)]. The results showed that the growth of Microcystis aeruginosa exhibited the hormesis phenomenon as a result of Y³⁺. Low concentrations of Y³⁺(0.10~0.20 mg·L^-1) could effectively improve the growth of Microcystis aeruginosa and enhance the activity of antioxidant enzymes under the condition of nitrogen and phosphorus deficiency, reducing the damage caused by the lack of nutrients. High concentrations of Y³⁺(0.50~2.00 mg·L^-1) exacerbated the damage caused by the nutrient deficiency. Photosynthetic pigments, soluble sugar, and soluble protein content decreased gradually, and the degree of membrane lipid peroxidation and the content of microcystin-LR showed apparent upward trends with the increase of Y³⁺ concentration.