Abstract

Diverse microbes in arable black soil participate in the biogeochemical cycling of nitrogen, which profoundly impact on the fertility and greenhouse gas (GHG) emission. However, the effects of environmental factors on the structure and functions of microbial communities have not been thoroughly elucidated. We performed the indoor microcosm study to collect the soil samples under six moisture (constant and wetting)/gas (air, 10% acetylene, oxygen and argon) regimes and investigated the alterations of bacterial community composition, nitrification/denitrification gene abundance and nitrogen metabolic functions under different conditions by high-throughput sequencing, quantitative PCR, physicochemical analyses and bioinformatics. It was found that the N₂O/CO₂ emission under six moisture/gas regimes were significantly different (p < 0.001), the processing time also dramatically influenced the GHG emission, and there were considerable interactions between moisture/gas regime and processing time. The impact of moisture/gas regimes, processing time and interaction item on \({\text{NH}}_{4}^{ + }\)-N and \({\text{NO}}_{3}^{ - }\)-N was also conspicuous. The moisture/gas regime significantly affected the community diversity rather than community richness. The key responsive bacterial classes under different gas conditions were Gammaproteobacteria, Bacteroidia and Alphaproteobacteria, in contrast to Actinobacteria, Alphaproteobacteria and Thermoleophilia under different moisture regimes. The abundance of Piscinibacter, Chujaibacter, Symbiobacteraceae and Acidobacteriales species was positively correlated with moisture and N₂O emission, and denitrification, nitrate reduction to ammonium, nitrification, nitrogen mineralization/fixation were the dominant processes of nitrogen cycle in black soil, which were supported by co-occurring network analyses and Spearman correlation heatmap. The hub nodes and connection mode of microbial nitrogen-cycling network differ under six moisture/gas regimes, and the same species could be active in multiple major nitrogen turnover processes simultaneously. These findings shed light on the prevention and control of soil fertility decline and global warming.

中文翻译：

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水分/气体状态对黑土微生物群落、网络配置和氮转换的影响

摘要

可耕黑土壤中的多种微生物参与氮的生物地球化学循环，对肥力和温室气体（GHG）排放产生深远影响。然而，环境因素对微生物群落结构和功能的影响尚未得到彻底阐明。我们进行了室内微观世界研究，在六种湿度（恒定和润湿）/气体（空气、10% 乙炔、氧气和氩气）状态下收集土壤样品，并研究了细菌群落组成、硝化/反硝化基因丰度和氮代谢的变化通过高通量测序、定量PCR、理化分析和生物信息学在不同条件下发挥作用。发现 N ₂ O/CO ₂六种水分/气体状态下的排放存在显着差异（p < 0.001），处理时间也显着影响温室气体排放，并且水分/气体状态与处理时间之间存在相当大的相互作用。水分/气体状态、处理时间和交互项对\({\text{NH}}_{4}^{ + }\) -N 和\({\text{NO}}_{3}^的影响{ - }\) -N 也很显眼。水分/气体状态显着影响群落多样性而不是群落丰富度。不同气体条件下的关键响应细菌类别是 Gammaproteobacteria、Bacterodia 和 Alphaproteobacteria，与不同水分条件下的 Actinobacteria、Alphaproteobacteria 和 Thermoleophilia 形成对比。丰富的Piscinibacter、Chujaibacter 、 Symbiobacteraceae 和 Acidobacteriales 物种与水分和 N ₂ O 排放呈正相关，反硝化、硝酸盐还原成铵、硝化、氮矿化/固定是黑土氮循环的主要过程。发生的网络分析和 Spearman 相关热图。微生物氮循环网络的枢纽节点和连接方式在六种水分/气体状态下存在差异，同一物种可以同时在多个主要氮循环过程中活跃。这些发现揭示了土壤肥力下降和全球变暖的预防和控制。