Wu Xueshen, Yu Zhong, Yuan Shasha, Tawfik Ahmed, Meng Fangang
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510006, China.
National Research Centre, Water Pollution Research Department, 12622, Dokki, Cairo, Egypt; Department of Environmental Science, College of Life Sciences, Kuwait University, P.O. Box 5969, Safat, 13060, Kuwait.
Water Res. 2023 Oct 21;247:120762. doi: 10.1016/j.watres.2023.120762.
The underlying mechanism associated with the roles of dosed carbon source in denitrification performance remains largely unknown. In this study, three denitrifying consortia (DNC) were constructed via evolutionary top-down enrichment method with well-defined conditions and specific carbon sources (acetate, glucose and their mixture). The reactor operation shows that nearly complete nitrate removal was achieved; however, the glucose feeding resulted in much higher concentrations of biomass and non-settable flocs. The 16S rRNA sequencing suggests that the bacterial diversity of the acetate-fed DNC was significantly higher than those of acetate/glucose-fed and glucose-fed DNCs. The dentrifying population in the acetate-fed DNC was dominated by Propionivibrio (16.1 %) and Thauera (3.4 %); whereas those of acetate/glucose- and glucose-fed DNCs were dominated by Pleomorphomonas (21.5 % and 26.3 %, respectively). Interestingly, the supernatant of acetate-fed DNC contained a high abundance of genera Thauera (averaged at 85.1 %), indicating the free-living nature of Thauera. Both PICURSt2 analysis of 16S rRNA sequencing and metagenomic analysis indicate that the acetate-fed DNC contained higher abundances of denitrifying genes; the acetate/glucose-fed and glucose-fed DNCs, in comparison, enriched genes related to glucose transportation and metabolism. Additionally, the acetate-fed DNC had better network stability than other two groups. This study adds important knowledge regarding the ecological traits of DNC, providing important clues for rational addition of carbon sources in wastewater treatment plants.
与定量碳源在反硝化性能中所起作用相关的潜在机制在很大程度上仍不清楚。在本研究中，通过进化自上而下富集方法，在明确的条件和特定碳源（乙酸盐、葡萄糖及其混合物）下构建了三个反硝化菌群（DNC）。反应器运行表明，实现了近乎完全的硝酸盐去除；然而，投喂葡萄糖导致生物量和不可沉降絮体的浓度高得多。16S rRNA测序表明，以乙酸盐为食的DNC的细菌多样性显著高于以乙酸盐/葡萄糖为食和以葡萄糖为食的DNC。以乙酸盐为食的DNC中的反硝化菌群以丙酸弧菌（16.1%）和陶厄氏菌（3.4%）为主；而以乙酸盐/葡萄糖为食和以葡萄糖为食的DNC则以多形单胞菌为主（分别为21.5%和26.3%）。有趣的是，以乙酸盐为食的DNC的上清液中含有高丰度的陶厄氏菌属（平均为85.1%），表明陶厄氏菌的自由生活性质。16S rRNA测序的PICURSt2分析和宏基因组分析均表明，以乙酸盐为食的DNC含有更高丰度的反硝化基因；相比之下，以乙酸盐/葡萄糖为食和以葡萄糖为食的DNC富集了与葡萄糖运输和代谢相关的基因。此外，以乙酸盐为食的DNC比其他两组具有更好的网络稳定性。本研究增加了关于DNC生态特征的重要知识，为污水处理厂合理添加碳源提供了重要线索。
