Different responses of representative denitrifying bacterial strains to gatifloxacin exposure in simulated groundwater denitrification environment
Different responses of representative denitrifying bacterial strains to gatifloxacin exposure in simulated groundwater denitrification environment
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模拟地下水反硝化环境中代表性反硝化菌株对加替沙星暴露的不同反应
DOI：
10.1016/j.scitotenv.2022.157929
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发表时间：
2022
影响因子：
9.8
通讯作者：
Fei Liu
中科院分区：
文献类型：
--
作者：
Baoshi Xu;Jiangtao He;Hua Zou;Jingang Zhang;Lu Deng;Meiping Yang;Fei Liu
抗生素对生态环境中反硝化作用的影响已引起广泛关注。然而，在某些研究中，同一种抗生素对混合微生物反硝化作用的浓度阈值和抑制效果存在矛盾。在本研究中，Paracoccus sp.和铜绿假单胞菌为代表菌株，探讨了单菌株对加替沙星（GAT）暴露在地下水反硝化作用中的响应。结果表明，当GAT浓度为10 μg/L时，铜绿假单胞菌对硝酸盐和亚硝酸盐的去除率分别下降了34.87- 36.25%和18.27- 23.31%，并伴随着硝化酶活性和基因表达的显著下降。相反，提高副球菌的硝化酶活性和基因表达可促进其对硝酸盐和亚硝酸盐的还原，分别为2.09- 10.00%和0- 8.44%。此外，在10 μg/L GAT存在下，对嗜酸菌去除硝酸盐和亚硝酸盐的效果不明显，这与嗜酸菌对硝酸盐和亚硝酸盐的降解酶活性和总基因表达量的影响一致。Monod方程及其修正的拟合结果进一步从反硝化动力学角度阐明了硝酸盐的降解特性。此外，抗生素抗性基因（ARG）分析表明，添加10 μg/L GAT（约30天）并没有显著增加ARG的相对丰度。本研究对地下水反硝化过程中代表性硝化细菌菌株对抗生素暴露的响应差异有了初步认识。·三株细菌对GAT暴露的反应不同。·硝酸盐降解过程符合Monod方程及其修正。·观察到了水解酶活性和DFG之间的协同效应。·暴露于GAT后，ARG的相对丰度没有显著增加。
The impact of antibiotics on denitrification in the ecological environment has attracted widespread attention. However, the concentration threshold and inhibitory effect of the same antibiotic on denitrification mediated by mixed denitrifying microbes were conflicting in some studies. In this study, Paracoccus denitrificans , Acidovorax sp., and Pseudomonas aeruginosa were selected as representative denitrifying bacterial strains to explore the response of a single strain to gatifloxacin (GAT) exposure in groundwater denitrification. The results showed that the nitrate and nitrite removal efficiencies of Pseudomonas aeruginosa decreased by 34.87–36.25 % and 18.27–23.31 %, respectively, with exposure to 10 μg/L GAT, accompanied by a significant decline in denitrifying enzyme activity and gene expression. In contrast, the elevated denitrifying enzyme activity and gene expression of Paracoccus denitrificans promoted its nitrate and nitrite reduction by 2.09–10.00 % and 0–8.44 %, respectively. Additionally, there were no obvious effects on the removal of nitrate and nitrite by Acidovorax sp. in the presence of 10 μg/L GAT, which was consistent with the variation in denitrifying enzyme activity and total gene expression levels. The fit results of the Monod equation and its modification further elucidated the nitrate degradation characteristics from the perspective of denitrification kinetics. Furthermore, antibiotic resistance gene (ARG) analysis showed that the addition of 10 μg/L GAT (approximately 30 days) did not observably increase the relative abundance of ARGs. This study provides some preliminary understanding of the response differences of representative denitrifying bacterial strains to antibiotic exposure in groundwater denitrification. • Responses of three denitrifying bacterial strains to GAT exposure were different. • Nitrate degradation process fitted the Monod equation and its modification. • Synergistic effect between denitrifying enzyme activities and DFGs was observed. • Relative abundance of ARGs did not increase significantly after exposure to GAT.