一株耐酸微藻的分离鉴定及其对锰离子胁迫的生理响应

Isolation and identification of an acid-tolerant microalgae and its physiological response to manganese ion stress

摘要:

[目的] 探讨在酸性含锰极端水环境中油球藻的生长特性及其对环境pH和Mn²⁺的影响。[方法] 从某硫铁矿山的酸性废水库中分离获得纯化藻株，通过形态观察及18S rRNA基因测序对其进行鉴定，并着重考察了不同pH和典型金属离子Mn²⁺浓度对其生长特性的影响，并通过测定藻生物量、光合色素、丙二醛（malondialdehyde，MDA）和还原型谷胱甘肽（reduced glutathione，GSH）含量以及超氧化物歧化酶（superoxide dismutase，SOD）、抗坏血酸过氧化物酶（ascorbate peroxidase，APX）比活力的变化，分析该藻对Mn²⁺胁迫的生理响应机制。[结果] 分离得到的藻株经鉴定为Graesiella sp.MA1；pH对该藻的生长有显著影响，其最低耐受初始pH为3.5；在初始pH为3.5和Mn²⁺浓度分别为5、30和55 mg/L时，藻细胞生物量随着Mn²⁺浓度的增加而下降，各试验组中的Mn²⁺浓度亦分别降低了28.62%、21.90%和18.84%，且pH值分别升高至5.7、5.6、5.4，对照组pH则高达9.1；在培养24 d后，藻细胞叶绿素a/b值随Mn²⁺浓度增加而下降，而MDA、GSH含量以及SOD、APX比活力则显著增加。结果表明，从酸性矿山废水库中分离纯化获得的油球藻能够同时耐受低pH和一定浓度范围内的Mn²⁺，在这种极端环境下，其细胞内的抗氧化系统缓减了膜脂质过氧化作用，从而在耐受重金属离子与解毒方面起到了重要作用。[结论] Graesiella sp.MA1具有耐受低pH、重金属离子以及产碱的作用，研究结果为利用油球藻开展酸性矿山废水原位生物修复提供了一定的理论依据。

关键词:锰离子;酸性条件;油球藻;抗氧化机制;酸性矿山废水

Abstract:

[Objective] The purpose of this study was to investigate the growth characteristics of Graesiella sp. and the influence of pH and Mn²⁺ in acidic manganese-containing extreme water environments. [Methods] The purified algae was isolated from an acid mine drainage in a pyrite mine and identified by morphological observation and 18S rRNA gene sequencing. Firstly, we investigated the effects of pH and typical metal ion Mn²⁺ concentration on its growth characteristics. Then, with the determination of algae biomass, photosynthetic pigment, malondialdehyde (MDA), reduced glutathione (GSH) content and the specific vitalities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), we analyzed the physiological response mechanism of the algae to Mn²⁺ stress.[Results] The isolated algae strain was identified and named as Graesiella sp. MA1. The medium pH had a significant effect on the growth of Graesiella sp. MA1, and its minimum initial tolerance pH was 3.5. When the initial pH was 3.5 and the concentration of Mn²⁺ was 5, 30 and 55 mg/L, the biomass of algal decreased with the increase of Mn²⁺ concentration. The Mn²⁺ concentration in experimental groups also decreased by 28.62%, 21.90% and 18.84%, respectively, and the pH value increased to 5.7, 5.6 and 5.4, respectively, while the pH value in control group was 9.1. After 24 days, the chlorophyll a/b value of algal decreased with the increase of Mn²⁺ concentration, while the contents of MDA and GSH, and the specific activities of SOD and APX increased significantly. The results showed that Graesiella sp. isolated and purified from acidic mine drainage could tolerate both low pH and Mn²⁺ in a certain concentration range. Under such extreme environment, the intracellular antioxidant system of Graesiella sp. could reduce membrane lipid peroxidation, and thus play an important role in tolerance of heavy metal ions and detoxification. [Conclusion] Graesiella sp. MA1 can tolerate low pH and heavy metal ions and generate alkalinity, thus this study provides a theoretical basis for in situ bioremediation of acidic mine drainage by using Graesiella sp..

Key words:manganese ion;acidic condition;Graesiella sp.;antioxidant mechanism;acid mine drainage