Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China; State Key Laboratory of Applied Microbiology Southern China, Guangzhou 510070, China.
Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China; State Key Laboratory of Applied Microbiology Southern China, Guangzhou 510070, China.
Sci Total Environ. 2021 Jan 1;750:141513. doi: 10.1016/j.scitotenv.2020.141513. Epub 2020 Aug 4.
Excessive nitrate in water systems is prevailing and a global risk of human health. Polluted river sediments are dominated by anaerobes and often the hotspot of denitrification. So far, little is known about the ecological effects of nitrate pollution on microbial dynamics, especially those in sulfide-rich sediments. Here we simulated a nitrate surge and monitored the microbial responses, as well as the changes of important environmental parameters in a sulfide-rich river sediment for a month. Our analysis of sediment microbial communities showed that elevated nitrate led to (i) a functional convergence at denitrification and sulfide oxidation, (ii) a taxonomic convergence at Proteobacteria, and (iii) a significant loss of biodiversity, community stability and other functions. Two chemolithotrophic denitrifiers Thiobacillus and Luteimonas were enriched after nitrate amendment, although the original communities were dominated by methanogens and syntrophic bacteria. Also, serial dilutions of sediment microbial communities found that Thiobacillus thiophilus dominated 18/30 communities because of its capability of simultaneous nitrate reduction and sulfide oxidation. Additionally, our network analysis indicated that keystone taxa seemed more likely to be native auxotrophs (e.g., syntrophic bacteria, methanogens) rather than dominant denitrifiers, possibly because of the extensive interspecific cross-feeding they estabilished, while environment perturbations probably disrupted that cross-feeding and simplified microbial interactions. This study advances our understanding of microbial community responses to nitrate pollution and possible mechanism in the sulfide-rich river sediment.
水体中硝酸盐过多是一个普遍存在的全球性问题，会对人类健康构成威胁。受污染的河底沉积物主要由厌氧菌主导，往往是反硝化作用的热点区域。迄今为止，人们对硝酸盐污染对微生物动态的生态影响知之甚少，特别是在富含硫化物的沉积物中。在这里，我们模拟了硝酸盐激增，并监测了微生物的响应，以及富含硫化物的河底沉积物中一个月内重要环境参数的变化。我们对沉积物微生物群落的分析表明，硝酸盐的增加导致：（i）在反硝化和硫化物氧化过程中的功能趋同；（ii）在变形菌门中的分类趋同；（iii）生物多样性、群落稳定性和其他功能显著丧失。尽管原始群落主要由产甲烷菌和共生细菌主导，但添加硝酸盐后，两种化能自养反硝化菌硫杆菌属和鲁特氏菌属得到了富集。此外，对沉积物微生物群落的连续稀释发现，由于其同时进行硝酸盐还原和硫化物氧化的能力，嗜酸硫杆菌属在 18/30 个群落中占据主导地位。此外，我们的网络分析表明，关键类群似乎更可能是原生营养缺陷型（例如，共生细菌、产甲烷菌），而不是优势反硝化菌，这可能是因为它们建立了广泛的种间交叉喂养关系，而环境扰动可能破坏了这种交叉喂养关系，并简化了微生物之间的相互作用。本研究增进了我们对富含硫化物的河底沉积物中微生物群落对硝酸盐污染的响应及其可能机制的理解。
