水环境中草甘膦对塔胞藻、塔玛亚历山大藻的毒性效应

The Toxicological Effects of Glyphosate to Pyramidomonas delicatula and Alexandrium tamarense in Water Environment

[目的]以江苏海州湾常见微藻塔胞藻(Pyramidomonas delicatula)、塔玛亚历山大藻(Alexandrium tamarense)为受试藻,研究水环境中草甘膦对2种微藻的致毒胁迫效应。[方法]以叶绿素a含量、超氧化歧化酶(SOD)、过氧化氢酶(CAT)活性及丙二醛(MDA)含量为指标,研究2种海洋微藻的生长及细胞内抗氧化系统对草甘膦致毒胁迫的响应。[结果]草甘膦质量浓度高于6.15 mg/L,对2种微藻表现出明显抑制作用,塔胞藻、塔玛亚历山大藻10.25 mg/L组培养至7 d,分别为对照组的5.9%、6.4%;96 h培养时间内,草甘膦对塔胞藻及塔玛亚历山大藻叶绿素a含量的影响表现在降低叶绿素a的合成量,呈现显著的质量浓度-剂量效应;低质量浓度草甘膦对2种微藻的SOD活性均表现诱导性上升,在10.25 mg/L恢复对照组水平;草甘膦对2种微藻的CAT活性表现微弱抑制;2种微藻体内MDA含量随草甘膦处理质量浓度增加而显著增长,塔胞藻、塔玛亚历山大藻在10.25 mg/L试验组达最高值,均为对照组16倍之多。[结论]高质量浓度(≥6.15 mg/L)的草甘膦可以有效抑制海洋微藻抗氧化酶活性,对塔胞藻、塔玛亚历山大藻具有强烈的致毒效应,不同的海洋微藻对农药残留致毒胁迫的响应存在较大的种属差异性。旨在提示农药污染对水环境破坏的严重性,揭示海洋微藻作为环境毒理学评价指标的潜在应用。

[Aims] Microalgae Pyramidomonas delicatula and Alexandrium tamarense that have a wide distribution in Haizhou Bay Jiangsu were used to assess the toxicity of glyphosate. [Mothods] The effects of activity of superoxide dismutase （SOD）, catalase （CAT）, and the total amounts of chlorophyll a and malondialdehyde （MDA） were chosen as toxic endpoints to study the cellular antioxidative response mechanisam of glyphosate stress. [Results] Two kinds of microalgae growth was inhibited significantly when the concentration of glyphosate were exceed 6.15 mg/L, the cell density ofP. delicatula and A. tamarense was reduced by 5.9 and 6.4% in the concentration group of 10.25 mg/L compared with control group respectively in 7 days; glyphosate can decreased chlorophyll a contents of these two microalgae with a significant dose-response relationship in 96 h; stimulating effect caused by low level of glyphosate can induce the activity of SOD while only weak inhibitory activity of CAT inhibition were found at 10.25 mg/L; the concentration of MDA in the cell of microalgae significantly increased with the increase of glyphosate and reached the peak at 10.25 mg/L which was 16 fold as high as that of the control group. [Conclusions] Glyphosate could inhibit effectively the activities of antioxidant enzymes of marine microalgae with strong toxicological effects. But the toxic response from different marine microalgae were significantly different in different cultivars. This article aims to prompt the severity of pesticide pollution to damage water environment, reveal marine microalgae＇s potential applications as environmental toxicology evaluation.