Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China.
Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China.
Environ Pollut. 2022 Jul 15;305:119322. doi: 10.1016/j.envpol.2022.119322. Epub 2022 Apr 18.
The fate of nitrogen is controlled by the competition between nitrate reduction pathways. Denitrification removes nitrogen in the system to the atmosphere, whereas dissimilatory nitrate reduction to ammonia (DNRA) retains nitrate in the form of ammonia. Different microbes specialize in the oxidation of different electron donors, thus electron donors might influence the outcomes of the competition. Here, we investigated the fate of nitrate with five forms of sulfur as electron donors. Chemoautotrophic nitrate reduction did not continue after the passages of the enrichments with sulfide, sulfite and pyrite. Nitrate reduction rate was the highest in the enrichment with thiosulfate. Denitrification was stimulated and no DNRA was observed with thiosulfate, while both denitrification and DNRA were stimulated with elemental sulfur. Metagenomes of the enrichments were assembled and binned into ten genomes. The enriched populations with thiosulfate included Thiobacillus, Lentimicrobium, Sulfurovum and Hydrogenophaga, all of which contained genes involved in sulfur oxidation. Elemental sulfur-based DNRA was performed by Thiobacillus (with NrfA and NirB) and Nocardioides (with only NirB). Our study established a link between sulfur sources, nitrate reduction pathways and microbial populations.
氮的命运由硝酸盐还原途径之间的竞争控制。反硝化将系统中的氮去除到大气中，而异化硝酸盐还原为氨（DNRA）则将硝酸盐以氨的形式保留在系统中。不同的微生物专门氧化不同的电子供体，因此电子供体可能会影响竞争的结果。在这里，我们研究了五种形式的硫作为电子供体时硝酸盐的命运。在进行了硫化物、亚硫酸盐和黄铁矿的富集培养后，化能自养硝酸盐还原就不再继续了。在硫代硫酸盐的富集培养中，硝酸盐的还原速率最高。硫代硫酸盐刺激了反硝化作用，没有观察到 DNRA，而单质硫则同时刺激了反硝化作用和 DNRA。对富集物的宏基因组进行了组装和分类，共分为十个基因组。含硫代硫酸盐的富集物包括硫杆菌属、 Lentimicrobium、Sulfurovum 和 Hydrogenophaga，它们都含有参与硫氧化的基因。基于单质硫的 DNRA 由硫杆菌（带有 NrfA 和 NirB）和 Nocardioides（仅带有 NirB）完成。我们的研究建立了硫源、硝酸盐还原途径和微生物种群之间的联系。
