Abstract：
Mining and tailings deposition can cause serious heavy metal(loids) pollution to the surrounding soil environment. Soil microorganisms adapt their metabolism to such conditions, driving alterations in soil function. This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids) exposure. The results showed that the diversity and abundance of nitrogen-cycling microorganisms showed negative feedback to heavy metal(loids) concentrations. Denitrifying microorganisms were shown to be the dominant microorganisms with over 60% of relative abundance and a complex community structure including 27 phyla. Further, the key bacterial species in the denitrification process were calculated using a random forest model, where the top three key species (Pseudomonas stutzei, Sphingobium japonicum and Leifsonia rubra) were found to play a prominent role in nitrite reduction. Functional gene analysis and qPCR revealed that nirK, which is involved in nitrite reduction, significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%. The experimental results confirmed that the activity of nitrite reductase (Nir) encoded by nirK in the soil was increased at high concentrations of heavy metal(loids). Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids), the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species. The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).
摘要：
采矿和尾矿沉积会对周围的土壤环境造成严重的重金属（微粒）污染。土壤微生物使其新陈代谢适应这种条件，驱动土壤功能的变化。本研究旨在阐明氮循环微生物在长期重金属（微粒）暴露下的反应模式。结果表明，氮循环微生物的多样性和丰度对重金属（微粒）浓度表现出负反馈。反硝化微生物被证明是优势微生物，相对丰度超过60％，群落结构复杂，包括27门。Further,使用随机森林模型计算反硝化过程中的关键细菌种类，前三个关键物种(Stutzei假单胞菌，日本狮身人面像和红叶Leifsoniarubra）在亚硝酸盐还原中起着重要作用。功能基因分析和qPCR显示，nirK，参与亚硝酸盐还原，在金属含量最高的土壤中显著积累，绝对丰度增加了63.86%。实验结果证实，在高浓度的重金属（loids）下，土壤中由nirK编码的亚硝酸还原酶（Nir）的活性增加。偏最小二乘路径模型确定了重金属（微粒）刺激的亚硝酸盐还原过程的三种潜在模式，其中最突出的是通过对关键物种的积极刺激来增强nirK丰度和土壤Nir活性。该结果为重金属（loids）刺激亚硝酸盐还原过程提供了新的见解和初步证据。
