State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.
Chemosphere. 2019 Nov;234:162-170. doi: 10.1016/j.chemosphere.2019.06.052. Epub 2019 Jun 10.
In this study, both the carbon and nitrogen metabolisms of two heterotrophic nitrification bacteria were investigated under aerobic and anaerobic conditions at 2 °C. Similar catabolism and anabolism trends were observed for the two bacteria in stable experimental systems under aerobic and anaerobic conditions. Based on the nitrogen and carbon balance analysis and adenosine triphosphate (ATP) calculation, we proposed the following metabolic pathways: i) aerobic: except for microbial assimilation, the carbon and nitrogen sources were removed through respiration and nitrification, which provided energy for cell synthesis; and ii) anaerobic: the nitrification process almost stopped and most of the carbon sources decomposed into inorganic carbon, which dissolved in the medium. Based on our proposed metabolic pathways, we speculated that the nitrifying process almost stopped under anaerobic conditions and the nitrification bacteria would degrade more carbon contaminants to produce energy and maintain the cell growth. Furthermore, these bacteria may decompose the non-readily biodegradable carbon through anaerobic degradation. To verify these hypotheses, experiments with two types of synthetic wastewater were conducted: i) synthetic wastewater rich in carbon and poor in nitrogen, and higher carbon removal efficiencies of strain J and strain P (∼25%) were obtained under anaerobic conditions compared with aerobic conditions (∼19%); and ii) synthetic wastewater with recalcitrant carbon sources, and carbon removal efficiencies under anaerobic conditions were higher than those under aerobic conditions. The results of the synthetic wastewater experiments were consistent with the hypotheses and thus validated the metabolic pathways proposed for carbon and nitrogen.
在这项研究中，两种异养硝化细菌的碳氮代谢在 2°C 下的有氧和厌氧条件下进行了研究。在有氧和厌氧稳定实验系统中，两种细菌表现出相似的分解代谢和合成代谢趋势。基于氮碳平衡分析和三磷酸腺苷 (ATP) 计算，我们提出了以下代谢途径：i）有氧：除微生物同化外，碳氮源通过呼吸和硝化作用去除，为细胞合成提供能量；ii）厌氧：硝化过程几乎停止，大部分碳源分解为无机碳，溶解在培养基中。基于我们提出的代谢途径，我们推测在厌氧条件下硝化过程几乎停止，硝化细菌会降解更多的碳污染物以产生能量并维持细胞生长。此外，这些细菌可能通过厌氧降解分解非易生物降解的碳。为了验证这些假设，进行了两种类型的合成废水实验：i）富碳贫氮的合成废水，在厌氧条件下，菌株 J 和菌株 P 的碳去除效率（约 25%）比有氧条件（约 19%）高；ii）含有难生物降解碳源的合成废水，在厌氧条件下的碳去除效率高于有氧条件。合成废水实验的结果与假设一致，从而验证了提出的碳氮代谢途径。
