钇对铅胁迫下铜绿微囊藻抗氧化能力及藻毒素释放的影响

Effects of Yttrium on Physiological Characteristics and Microcystins Release of Microcystic aeruginosa with Pb^(2+) Stress

为探讨稀土钇(Y3+)质量浓度对铅胁迫下铜绿微囊藻(Microcystic aeruginosa)生理特性及藻毒素含量的影响,用不同质量浓度钇作用于1.00mg·L-1Pb2+胁迫下的铜绿微囊藻,绘制铜绿微囊藻的生长曲线并测定超氧化物歧化酶(SOD)、过氧化氢酶(POD)、过氧化物酶(CAT)活性、丙二醛(MDA)及藻毒素-LR(MC-LR)含量。结果表明:在铅胁迫下,低质量浓度Y3+(0.10～0.50mg·L-1)改善了铅胁迫下铜绿微囊藻的生长,而高质量浓度Y3+(1.00～10.00mg·L-1)则加剧了对铜绿微囊藻的毒害作用;在Y3+质量浓度升高时,藻细胞丙二醛(MDA)和溶液中藻毒素MC-LR含量大量增加,抗氧化酶活性均下降,藻细胞清除活性氧(ROS)能力减弱,抗氧化防御系统被破坏,膜脂过氧化严重,严重抑制藻细胞生长。在铅胁迫下,钇对铜绿微囊藻产生"低促-高抑"的Hormesis效应显著。

In order to study the effects of different yttrium（Y^3＋） concentrations on the physiology and microcysin-LR（MC-LR）,the M.aeruginosa FACHB912 was used in this work. The effects of different Y^3＋ concentration on M.aeruginosa under 1.00 mg·L^-1 Pb2＋ stress were investigated. Based on the growth curve of M.aeruginosa, the activity of antioxidant enzymes including SOD, POD, CAT, and the content of malondiadehyde（MDA） and microcystic toxins（MC-LR）, results showed that obvious auxo-actions to the growth of M.aeruginosa, could be observed at relatively low concentrations of Y^3＋（0.10~0.50 mg·L^-1） with Pb stress. Correspondingly, the activities of SOD, POD, and CAT in M.aeruginosa were enhanced, and the MDA presented decrease significantly. When the higher concentrations（1.00~10.00 mg·L^-1） of Y^3＋ was employed, more severely inhibition to the growth of M.aeruginosa could be observed. When the concentrations were in the range of 0.50~10.00 mg·L^-1, the content of MDA and MC-LR increased immediately and the activity of antioxidant enzymes was reduced, which potentially lead to the decline of the ability of eliminating the reactive oxygen species. Moreover, the antioxidant defense system was destroyed, and the growth of M.aeruginosa was seriously inhibited correspondingly. The typical ＂Hormesis＂ effects can be observed as the yttrium was employed on M.aeruginosa.