Chair of Soil Science, TUM School of Life Sciences Weihenstephan, Technical University Munich, Emil-Ramann-Straße 2, 85354 Freising, Germany.
Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
FEMS Microbiol Ecol. 2021 Mar 8;97(3). doi: 10.1093/femsec/fiab004.
Globally occurring nitrate pollution in groundwater is harming the environment and human health. In situ hydrogen addition to stimulate denitrification has been proposed as a remediation strategy. However, observed nitrite accumulation and incomplete denitrification are severe drawbacks that possibly stem from the specific microbial community composition. We set up a microcosm experiment comprising sediment and groundwater from a nitrate polluted oxic oligotrophic aquifer. After the microcosms were sparged with hydrogen gas, samples were taken regularly within 122 h for nitrate and nitrite measurements, community composition analysis via 16S rRNA gene amplicon sequencing and gene and transcript quantification via qPCR of reductase genes essential for complete denitrification. The highest nitrate reduction rates and greatest increase in bacterial abundance coincided with a 15.3-fold increase in relative abundance of Rhodocyclaceae, specifically six ASVs that are closely related to the genus Dechloromonas. The denitrification reductase genes napA, nirS and clade I nosZ also increased significantly over the observation period. We conclude that taxa of the genus Dechloromonas are the prevailing hydrogenotrophic denitrifiers in this nitrate polluted aquifer and the ability of hydrogenotrophic denitrification under the given conditions is species-specific.
全球范围内地下水中的硝酸盐污染正在危害环境和人类健康。向地下水中添加原位氢气以刺激反硝化作用已被提议作为一种修复策略。然而，观察到的亚硝酸盐积累和不完全反硝化是严重的缺点，这可能源于特定的微生物群落组成。我们建立了一个包含来自硝酸盐污染好氧贫营养含水层的沉积物和地下水的微宇宙实验。在微宇宙中注入氢气后，在 122 小时内定期取样进行硝酸盐和亚硝酸盐测量、16S rRNA 基因扩增子测序进行群落组成分析以及通过 qPCR 对完成反硝化作用所需的还原酶基因进行基因和转录物定量。硝酸盐还原率最高和细菌丰度最大的时期与 Rhodocyclaceae 的相对丰度增加了 15.3 倍相对应，特别是与属 Dechloromonas 密切相关的六个 ASV。脱氮还原酶基因 napA、nirS 和 I 型 nosZ 在观察期间也显著增加。我们得出结论，属 Dechloromonas 的分类群是这种硝酸盐污染含水层中占优势的氢营养型反硝化菌，并且在给定条件下氢营养型反硝化作用的能力是具有物种特异性的。
