Denitrifying microbial communities play a central role in the nitrogen cycle, contribute to greenhouse gas production, and provide ecosystem services through the mitigation of nitrogen pollution. The impacts of human-induced acid mine drainage (AMD) and naturally occurring acid rock drainage (ARD), both characterized by low pH and high metal concentrations, on denitrifying microbial communities is not well understood. This study examined denitrifying microbes within sediments impacted by acidic and metal-rich AMD or ARD in the Iron Springs Mining District (10 sites across four regions over four time points) located in Southwest Colorado, USA. Denitrification functional gene sequences (nirS and nirK coding for nitrite reductase) had a high number of observed OTUs (260 for nirS and 253 for nirK) and were observed at sites with pH as low as 3.5 and metals > 2 mg/L (including aluminum, iron, manganese, strontium, and zinc). A majority of the nirK and nirS OTUs (> 60%) were present in only one sampling region. Approximately 8% of the nirK and nirS OTUs had a more cosmopolitan distribution with presence in three or more regions. Phylogenetically related OTUs were found across sites with very different chemistry. The overall community structure for nirK and nirS genes was correlated to conductivity and calcium (respectively), which may suggest that conductivity may play an important role in shaping the distribution of nirK- and nirS-type denitrifiers. Overall, these findings improve upon our understanding of the potential for denitrification within an ecosystem impacted by AMD or ARD and provide a foundation for future research to understand the rates and physiology of denitrifying organisms in these systems.

中文翻译：

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酸性矿山排水环境中亚硝酸盐还原酶基因序列的群落组成。

反硝化微生物群落在氮循环中起着重要作用，有助于减少温室气体的产生，并通过减轻氮污染来提供生态系统服务。人为诱发的酸性矿山排水（AMD）和自然发生的酸性岩矿排水（ARD）（以低pH和高金属浓度为特征）对反硝化微生物群落的影响尚不清楚。这项研究检查了位于美国西南科罗拉多州铁泉矿区（四个时间点在四个地区的四个地区有10个站点）受酸性和富含金属的AMD或ARD影响的沉积物中的反硝化微生物。反硝化功能基因序列（编码亚硝酸还原酶的nirS和nirK）具有大量观察到的OTU（nirS为260，nirK为253），并且在pH值低至3的位置观察到。5和> 2 mg / L的金属（包括铝，铁，锰，锶和锌）。大多数nirK和nirS OTU（> 60％）仅存在于一个采样区域。大约8％的nirK和nirS OTU具有较国际化的分布，分布在三个或更多地区。系统发育相关的OTU在化学性质完全不同的站点之间发现。nirK和nirS基因的整体群落结构分别与电导率和钙相关，这可能表明电导率可能在塑造nirK和nirS型反硝化剂的分布中起重要作用。总体，