Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91, Stockholm, Sweden.
Baltic Sea Centre, Stockholm University, Stockholm, Sweden.
Microb Ecol. 2023 Nov;86(4):2357-2372. doi: 10.1007/s00248-023-02241-7. Epub 2023 May 24.
Denitrification in sediments is a key microbial process that removes excess fixed nitrogen, while dissimilatory nitrate reduction to ammonium (DNRA) converts nitrate to ammonium. Although microorganisms are responsible for essential nitrogen (N) cycling, it is not yet fully understood how these microbially mediated processes respond to toxic hydrophobic organic compounds (HOCs) and metals. In this study, we sampled long-term polluted sediment from the outer harbor of Oskarshamn (Baltic Sea), measured denitrification and DNRA rates, and analyzed taxonomic structure and N-cycling genes of microbial communities using metagenomics. Results showed that denitrification and DNRA rates were within the range of a national reference site and other unpolluted sites in the Baltic Sea, indicating that long-term pollution did not significantly affect these processes. Furthermore, our results indicate an adaptation to metal pollution by the N-cycling microbial community. These findings suggest that denitrification and DNRA rates are affected more by eutrophication and organic enrichment than by historic pollution of metals and organic contaminants.
沉积物中的反硝化作用是一种去除过量固定氮的关键微生物过程，而异化硝酸盐还原为铵（DNRA）则将硝酸盐转化为铵。尽管微生物是重要氮（N）循环的主要贡献者，但目前还不完全清楚这些微生物介导的过程如何响应有毒疏水性有机化合物（HOCs）和金属。在这项研究中，我们从奥斯卡港（波罗的海）外港采集了长期受污染的沉积物样本，测量了反硝化和 DNRA 速率，并使用宏基因组学分析了微生物群落的分类结构和 N 循环基因。结果表明，反硝化和 DNRA 速率处于国家参考站点和波罗的海其他未受污染站点的范围内，这表明长期污染并未显著影响这些过程。此外，我们的结果表明，N 循环微生物群落已经适应了金属污染。这些发现表明，反硝化和 DNRA 速率受富营养化和有机富积的影响大于历史金属和有机污染物污染的影响。
