纳米氧化锌和菲对长江口附近海域沉积物反硝化作用及功能菌群落结构的影响

本研究在长江口附近海域采集表层沉积物,采用实验室模拟培养与分子生物学手段相结合的方法,通过测定纳米氧化锌(ZnO NPs)和菲(Phe)胁迫下沉积物中NO^-₃-N和NO^-₂-N浓度和反硝化还原酶活性及反硝化细菌基因丰度和群落多样性变化,目的是比较研究ZnO NPs和Phe对河口区沉积物反硝化作用及功能菌群落结构的影响,并探讨其作用过程和可能的作用机制。结果表明:ZnO NPs和Phe对沉积物硝酸盐还原能力和亚硝酸还原能力均产生抑制作用,浓度越高,抑制作用越强,其中亚硝酸盐还原过程受到2种污染物抑制更强烈,加重了沉积物亚硝酸盐的累积。ZnO NPs对沉积物硝酸盐还原能力、硝酸还原酶活性、narG基因丰度的抑制程度大于Phe,Phe对沉积物亚硝酸盐还原能力、亚硝酸还原酶和nirS基因丰度的抑制程度大于ZnO NPs,表明对反硝化还原酶和反硝化功能基因的抑制是外源污染物胁迫影响反硝化过程的主要机制。ZnO NPs和Phe降低了沉积物反硝化菌群落多样性水平,增加沉积物中Halomonas的优势度,降低了Bacillus的优势度,但Phe对沉积物群落多样性和组成的影响更加明显,说明Phe对长江口海区的生态影响大于ZnO-NPs。

Effects of Zinc Oxide Nanoparticles and Phenanthrene on Denitrification and Denitrifying Bacteria Communities of Sediments in the Sea Area Near the Yangtze River Estuary

For comparing the effects of ZnO NPs with Phe on denitrification and denitrifying bacteria communities in estuarine sediments and revealing their action process and possible mechanism,surface sediments were collected from the Yangtze River estuary and then anaerobic cultured in laboratory.The NO^-₃,NO^-₂concentration and NO^-₃,NO^-₂reductase activity in sediments were measured by physicochemical analysis,nirSgene abundance,denitrifying bacteria communitiesby molecular biological methods.The results showed that ZnO NPs inhibited NO^-₃,NO^-₂reduction capacity and a stronger inhibition effect resulting from the higher ZnO NPs concentration.The reduction process of nitrite was more strongly inhibited by two pollutants,which aggravated the accumulation of nitrite in sediment.The inhibition degrees of ZnO NPs on nitrate reduction capacity,nitrate reductase activity and narGgene abundance in sediments were higher than those of Phe,and the inhibition degrees of Phe on nitrite reduction ability,nitrite reductase and nirSgene abundance in sediments were higher than those of ZnO NPs,which indicated that the inhibitions of denitrifying reductases and denitrifying function genes were important mechanism of exogenous pollutant stress affecting denitrification.ZnO NPs and Phe reduced the diversity level of denitrifying bacteria in sediments and changed some denitrifying bacteria dominance,including the increase of Halomonas and the decrease of Bacillus in sediments.However,the effects of Phe on diversity and composition of denitrifying bacteria in sediments were more obvious,indicating that the ecological effects of Phe on the Yangtze River estuary were greater than those of ZnO NPs.