藻菌共生体砷吸收和形态转化规律的研究

Arsenic (As) pollution control and remediation have received a considerable attention in the field of environmental science. Consortia of microalgae and bacteria are efficient in the removal of pollutants such as nitrogen and phosphorus in water. However, their applications in the treatment of As-containing wastewater were seldom reported. We hypothesize that microalgal–bacteria association may increase As uptake and detoxification based on our previous study on the As removal by the consortia of Dunaliella salina and Bacillus solisalsi. Research will be conducted on the interaction between microalgae and associated bacteria and As absorption and speciation transformation. In order to varify the above hypothesis, this project will construct consortia of microalgae and bacteria, separate, purify and culture each component. Various As species and concentrations will be applied to the consortia, microalgae and bacteria. Growth characteristics, As tolerance, uptake and biotransformation will be investigated in order to reveal the mechanisms of As adsorption, absorption and detoxification by the consortia of microalgae and bacteria. The results of this research may be of great significance in the bioremediation of As pollution in water and in the risk reduction of this toxic element to the environment and human health.

砷污染的控制和修复是环境科学领域的热点问题之一。藻菌共生体对水中氮磷等污染物有良好的净化效果，然而其对含砷废水的治理还鲜有报道。本项目在课题组前期对盐藻—芽孢杆菌共生体除砷的工作基础上，提出"藻菌共生增强砷吸收和脱毒效果"的假设，研究微藻和共生细菌的相互作用及其对砷的吸收和形态转化的规律。为验证这一假设，本项目将构建微藻和细菌共生体系，同时进行微藻和细菌的分离纯化培养，设置不同形态和浓度的砷处理，研究藻菌共生体、微藻及细菌的生长特性、对砷的耐性、吸收和形态转化，揭示藻菌共生增强砷吸附、吸收和解毒的机制。研究结果可为含砷废水的生物治理提供理论依据，对降低砷对生态环境和人体健康的风险具有十分重要的意义。

微藻细胞表面和周围存在多种细菌，这些细菌制约微藻的生长，因而对微藻砷富集和代谢也有不可忽略的影响。针对共生细菌对微藻砷吸附吸收、形态转化影响结果不一、规律不清的问题，本项目采用盐藻和小球藻为供试材料，分离并鉴定了与上述两种微藻共生的细菌，研究了带菌微藻、无菌微藻以及共生细菌对砷（砷酸盐和亚砷酸盐）的富集和代谢规律。结果表明：.1）盐藻共生细菌为麦氏交替单胞菌，小球藻的共生细菌为盐单胞菌，这些细菌都促进盐藻和小球藻的生长，增强了微藻对砷的耐性。.2）砷酸盐处理下，共生细菌增加了小球藻对砷的吸附、减少了对砷的吸收，藻细胞中以As(V)为主要砷形态；共生细菌对盐藻的影响还受到培养基磷酸盐的制约，磷酸盐充足时，共生细菌促进了盐藻对砷的富集，藻细胞As(V)为主要砷形态，而磷酸盐缺乏时，带菌盐藻胞内砷含量降低，形态以As(III)和甲基砷为主。.3）亚砷酸盐处理下，共生细菌增加了小球藻对砷的富集，促进了亚砷酸盐的氧化，胞内和培养液的As(V)比例显著增加。.以上结果深化了我们对微藻--细菌共生关系和藻菌共生体砷富集和代谢规律的认识，上述成果对揭示藻菌砷代谢的机制、推进微藻--细菌在砷污染水体的联合修复方面都具有重要意义。