日本真海带对硒的积累和生物转化

Accumulation and biotransformation of selenium in kelp Laminaria japonica

在海水中添加亚硒酸盐（Na2SeO3）及不同浓度的氮磷营养盐（NaNO3＋NaH2PO4），研究海带对硒的积累，通过分离测定海带富硒前后各生化组分的含硒量来探讨硒的生物转化问题．结果表明天然海带含硒量（鲜重）为0．451～0．596μg／g，海带富硒最佳的Na2SeO3浓度为200mg／dm^3，培养56h后的富硒倍率约为50．在天然海带中，硒主要以有机态存在，有机硒占总硒含量的86．22％；在含有200mg／dm^3 Na2SeO3的海水中培养56h后测得海带的总硒为24．481μg／g，其中有机硒含量为16．703μg／g，无机硒为4．714μg／g；在添加氮磷营养盐的含硒海水中，海带的富硒能力得到进一步的提高，在适宜的氮磷条件下（150mg／dm^3 NaNO3和25mg／dm^3 NaH2PO4）总硒含量达到33．649μg／g，而无机硒含量基本不变，为4．497μg／g，因此提高部分转化为有机硒，有机硒含量达到24．678μg／g．这说明海带具有通过自身代谢将无机硒转化为有机硒的较强的能力．

Accumulations of selenium in kelp （Larninaria japonica） cultured in seawater were achieved by adding selenite （NazSeO3） with or without N and P （NaNO3＋NaH2PO4） nutrient of different concentrations. Biotransformation of selenium in the Kelp was investigated through measuring the selenium of biological samples and different biochemical fractionations. The results show that the total selenium content in kelp （fresh weight） is 0. 451～0. 577 μg/g before accumulation. The optimal concentration of Na2SeO3 is 200 mg/dm^3 and the concentration of selenium is 20. 558～25. 811 μg/g after exposing for 56 h in seawater containing 200 mg/dm^3 Na2SeO3. This demonstrates that the kelp has good capability of accumulating selenium. Analysis of selenium composition in the kelp （control group） shows that selenium is predominately present as organic selenium which is up to 86.22% of total selenium. When the kelp exposing for 56 h in seawater containing 200 mg/dm^3 Na2SeO3, the total selenium is 24. 481μg/g in which organic selenium is 16. 703 μg/g, inorganic selenium 4. 714 μg/g. The capability of accumulation of selenium was further enhanced by adding N-P nutrient to the selenite enriched mediurn. Total selenium is increased by 33. 649 μg/ g at optimal concentration of N-P nutrient （150 mg/dm^3 NaNO3 and 25 mg/dm^3 NaH2PO4）, whereas the inorganic selenium is not increased and kept as 4. 497μg/g, and the increased part of selenium is organic selenium. This implies that kelp Laminaria japonica could effectively transform inorganic selenium into organic selenium through metabolism.