Abstract：
The microbial oxidation of short-chain gaseous alkanes (SCGAs, consisting of ethane, propane, and butane) serves as an efficient sink to mitigate these gases\' emission to the atmosphere, thus reducing their negative impacts on air quality and climate. \"Candidatus Alkanivorans nitratireducens\" are recently found to mediate nitrate-dependent anaerobic ethane oxidation (n-DAEO). In natural ecosystems, anaerobic ammonium-oxidizing (anammox) bacteria may consume nitrite generated from nitrate reduction by \"Ca. A. nitratireducens\", thereby alleviating the inhibition caused by nitrite accumulation on the metabolism of \"Ca. A. nitratireducens\". Here, we demonstrate the coupling of n-DAEO with anammox in a laboratory-scale model system to prevent nitrite accumulation. Our results suggest that a high concentration of ethane (6.9-7.9%) has acute inhibition on anammox activities, thus making the coupling process a significant challenge. By maintaining ethane concentrations within the range of 1.7-5.5%, stable ethane and ammonium oxidation, nitrate reduction, and dinitrogen gas generation without nitrite accumulation were finally achieved. After the accomplished coupling of n-DAEO with anammox, nitrate reduction rates increased by 8.1 times compared to the rate observed with n-DAEO alone. Microbial community profiling via 16S rRNA gene amplicon sequencing showed \"Ca. A. nitratireducens\" (6.6-12.9%) and anammox bacteria \"Candidatus Kuenenia\" (3.4-5.6%) were both dominant in the system, indicating they potentially form a syntrophic partnership to jointly contribute to nitrogen removal. Our findings offer insights into the cross-feeding interaction between \"Ca. A. nitratireducens\" and anammox bacteria in anoxic environments.
摘要：
短链气态烷烃的微生物氧化(SCGA，由乙烷组成，丙烷,和丁烷)充当有效的汇，以减轻这些气体向大气的排放，从而减少它们对空气质量和气候的负面影响。最近发现“CandidatusAlkanivorans硝酸盐还原”介导硝酸盐依赖性厌氧乙烷氧化（n-DAEO）。在自然生态系统中,厌氧氨氧化（anammox）细菌可能会消耗由Ca还原硝酸盐产生的亚硝酸盐。A.硝化还原\“，从而减轻亚硝酸盐积累对Ca代谢的抑制作用。A.硝化还原\“。这里,我们在实验室规模的模型系统中证明了n-DAEO与anammox的耦合，以防止亚硝酸盐积累。我们的结果表明，高浓度的乙烷（6.9-7.9％）对anammox活性具有急性抑制作用，从而使耦合过程成为一个重大挑战。通过将乙烷浓度保持在1.7-5.5％的范围内，稳定的乙烷和铵氧化，硝酸盐还原，最终实现了无亚硝酸盐积累的双氮气体产生。在完成n-DAEO与anammox的偶联后，与单独使用n-DAEO观察到的硝酸盐还原率相比，硝酸盐还原率增加了8.1倍。通过16SrRNA基因扩增子测序进行的微生物群落分析显示\“Ca。硝化还原菌（6.6-12.9%）和厌氧氨氧化菌“Kuenenia念珠菌”（3.4-5.6%）在系统中均占主导地位，表明它们可能形成一种互养伙伴关系，共同促进氮的去除。我们的发现为Ca之间的交叉进食相互作用提供了见解。缺氧环境中的硝化还原菌和厌氧氨氧化菌。
