不同添加剂强化低丰度厌氧氨氧化菌群的比较

以来源于一体式部分亚硝化-厌氧氨氧化(combined partial nitrification-anammox,CPNA)序批式反应器(sequencing batch reactor,SBR)工艺的活性污泥为对象,通过厌氧批式实验,比较3种添加剂(Fe^(2+)、氧化石墨烯、Fe^(3+))投加后对厌氧氨氧化菌的脱氮效果、活性、关键功能基因数量、群落结构和功能丰度的影响。实验结果表明:经过42 d的厌氧培养后,3种添加剂对厌氧氨氧化脱氮性能都有一定的强化作用,投加氧化石墨烯提高效果最好,它的总氮去除率最高能达到76.01%,平均总氮去除率高于对照组22.71%;而投加Fe^(2+)和Fe^(3+)组的平均总氮去除率分别仅高于对照组5.69%和1.72%。投加3种添加剂均能提高厌氧氨氧化菌活性,其中氧化石墨烯组的活性比对照组提高8.08%,Fe^(3+)组的活性比对照组提高10.02%。投加氧化石墨烯对厌氧氨氧化菌代谢过程中hzo基因数量的提高效果最好,比对照组提高6.83倍,投加Fe^(2+)和Fe^(3+)分别比对照组提高5.14倍和4.90倍;且投加氧化石墨烯对浮霉菌门富集扩培效果最好,其丰度比对照组提高44.51%,而投加Fe^(2+)和Fe^(3+)后丰度结果分别比对照组提高1.03%和稍低于对照组。投加氧化石墨烯对微生物代谢功能的提升效果最佳。

Seasonal changes of organic matter origins and anammox activity in the Changjiang Estuary deduced from multi-biomarkers in suspended particulates

Human activity-induced eutrophication and harmful algal blooms are main causes of the expansion of the hypoxic zone in the Changjiang Estuary. Among the many changes in biogeochemical processes, anaerobic ammonium oxidation(anammox) is proposed to play an important role in the nitrogen cycle in hypoxic areas. Ladderane lipids have been used as biomarkers to indicate anammox activity in ecosystems, but the origins of anammox bacteria and ladderanes in suspended particulates are still unclear. In this study, we report the results of a suite of biomarker analyses of suspended particulates across a salinity gradient of the Changjiang Estuary in both the spring and summer to evaluate the origins of the ladderanes and their potential as proxies for anammox activity and hypoxia. The spatio-temporal variations in terrestrial biomarkers(n-alkanes and n-alkanols), marine biomarkers(brassicasterol and dinosterol), and the Terrestrial and Marine Biomarker Ratio and Branched and Isoprenoid Tetraether indices reveal that marine organic matter was dominant in the particulates in both the spring(55%) and summer(86%) seasons. Correlations with both marine and terrestrial biomarkers suggest that ladderanes were mainly produced in the water column, and therefore that ladderane concentrations in suspended particulates in the Changjiang Estuary mainly reflect anammox activity in the water column, although changes in anammox bacterial assemblages may also have played a role in ladderane concentrations. Overall, ladderane results suggest that anammox activity was widespread in the Changjiang Estuary; but higher ladderane concentrations in the summer(especially in the upwelling zone) were correlated with lower dissolved oxygen concentrations, which suggest that they are useful proxies for hypoxia.