Abstract:

In order to reveal the dibenzothiophene (DBT) degradation pathway in Bohai Rim typical wetland sediments at different temperatures, three different types of wetland sediments were chosen: reed wetland sediments (RWS) collected from Liao River estuary, tidal wetlands sediments (TWS) collected from Beida harbor and estuary wetland sediments (EWS) collected from Yellow River estuary. These samples were cultured for 56 days under the condition of simulating the seasonal temperature. The degradation rates were determined and the abundance of DBT degradation functional genes were analyzed. The DBT degradation pathways in different wetland sediments and at different temperatures were analyzed using a quantitative response model established between DBT degradation rate and degradation functional gene groups. Results show that the degradation rate and the abundance of degradation functional genes are basically improved with the increase of temperature. At 4ºC, the trend of DBT degradation rate is EWS>TWS>RWS; while at 30ºC, it is TWS>EWS>RWS. Functional genes catA and dszB affect DBT degradation rate. Kodama pathway functional genes nagAc/nahAc and nidA are the main functional genes for DBT degradation in all the three typies of wetland sediments at low temperature while nidA is the the main at medium temperature. The 4S pathway gene dszB plays an important role for DBT degradation.

Key words: dibenzothiophene, wetland sediments, Bohai Rim, functional genes, degradation pathway

摘要：

为了揭示不同温度下环渤海典型湿地沉积物中二苯并噻吩(DBTs)的降解途径, 选择辽河口芦苇湿地、天津北大港滩涂湿地和黄河河口湿地的3种不同湿地沉积物, 在模拟季节性温度条件下, 培养56天, 测定DBT的降解率, 分析DBT降解功能基因的丰度, 建立DBT降解率与功能基因群组定量响应关系模型, 解析不同温度下3种湿地沉积物中DBT的降解途径。实验结果表明, 3种湿地沉积物中DBT的降解率均随培养温度升高而升高, 4ºC培养时, DBT的降解率排序为黄河河口湿地>天津北大港滩涂湿地>辽河口芦苇湿地; 30ºC培养时, DBT的降解率排序为北大港滩涂湿地>黄河河口湿地>辽河口芦苇湿地; catA与dszB基因影响DBT的降解速率。低温条件和中温条件下, 在3种湿地中, 代表Kodama途径的nagAc/nahAc和nidA基因分别起主要作用, 代表4S途径的dszB基因在黄河河口湿地及北大港滩涂湿地中有重要作用。

关键词: 二苯并噻吩, 湿地沉积物, 环渤海, 功能基因, 降解途径