带菌盐藻对不同形态砷的富集和转化研究

Accumulation and Transformation of Different Arsenic Species in Nonaxenic Dunaliella salina

自然环境中藻和菌多是共生的，藻菌共生体对污染环境修复具有较好的应用前景．本研究通过16SrRNA序列分析方法从带菌盐藻中分离鉴定出1株芽胞杆菌（Bacillussolisalsi），并测定了不同浓度的亚砷酸盐[As（Ⅲ）]和砷酸盐[（As（Ⅴ）]胁迫13d后，带菌盐藻对砷的吸收、吸附、转化情况以及培养液中的砷含量及其形态．结果表明，无菌盐藻对砷的耐性较强，在250μmol·L-1和500μmol·L-1 As（Ⅲ）胁迫下，砷含量分别为3．78g·kg-1和4．56g·kg1-，但是培养液中的砷含量仅下降7．9％-8．3％，Bacillussolisalsi单独除砷的能力也不强（去除率为6．1％-19．9％）．盐藻及其共生菌协同除砷的能力较强，25-100μmol·L。As（Ⅲ）处理下能吸收0．99-2．79g·kg-1的砷，25-500μmol·L-1As（Ⅴ）处理下能吸收1．22-3．46g·kg-1的砷．25-100μmol·L-1As（Ⅲ）和As（V）胁迫下砷去除率均在54．3％以上．带菌盐藻可以通过As（Ⅲ）氧化、As（Ⅴ）还原、As（Ⅲ）甲墓化和排出胞外等涂释隆低砷的毒害．

Algae and bacteria are usually symbiotic in the environment. The algae-bacteria consortia have a good prospect in the remediation of polluted environment. In this study, we isolated a bacterium from nonaxenic Dunaliella salina and identified it as Bacillus solisalsi using 16S rRNA sequence analysis. The uptake, adsorption and transformation of As by the nonaxenic D. salina and the concentration and speciation of As in the culture solution were determined after 13 days exposure to various concentrations of As（ Ⅲ ） and As（ Ⅴ ）. The results showed that D. salina had a high As tolerance. When the algae was exposed to 250 μmol. L-1 and 500 μmol. L- 1 arsenite, As accumulations were 3.78 g. kg-1 and 4. 56 g. kg-1, respectively, but the As removal from the solution was 7.9%-8.3%. B. solisalsi did not show a strong ability to clean up As either （6.1%-19.9% removal rate）. The consortia of D. salina and B. solisalsi showed a higher As removal ability. Moreover, 0. 99-2.79 g.kg-1 and 1.22-3.46 g.kg-1 As were absorbed when exposed to 25-100 μmol.L-1 and 25-500 μmol. L-1 As（ Ⅲ） and As（ Ⅴ ） , respectively. More than 54.3% of As were taken away by the consortia from the solution under the exposure of 25-100 μmol. L-1 As（ Ⅲ ） and As（ Ⅴ ）. Various pathways of As detoxification were identified for the nonaxenic D. salina： As（ Ⅲ ） oxidation, As（ Ⅴ） reduction, As（ Ⅲ ） methylation, and efflux of As from cells.