中文关键词硝化作用氨氧化微生物多样性休眠群落结构 英文关键词nitrificationammonia-oxidizing microorganismsdiversitydormancycommunity structure

作者	单位	E-mail
刘天琳	西南大学资源环境学院, 重庆 400715	15802354130@163.com
王智慧	西南大学资源环境学院, 重庆 400715
闫小娟	西南大学资源环境学院, 重庆 400715
赵永鹏	西南大学资源环境学院, 重庆 400715
贾仲君	中国科学院南京土壤研究所, 土壤与农业可持续发展国家重点实验室, 南京 210008
蒋先军	西南大学资源环境学院, 重庆 400715	jiangxj@swu.edu.cn

中文摘要 研究表明酸性土壤中氨氧化作用主要是由氨氧化古菌（ammonia-oxidizing archaea，AOA）催化进行；而在中性和碱性土壤中则主要是由氨氧化细菌（ammonia-oxidizing bacteria，AOB）主导.虽然AOA在中性土壤中具有很高的丰度，但其对硝化过程的贡献仍不清楚.因此本文选取pH为7.2的中性紫色土为研究对象，通过稳定性同位素核酸探针技术结合克隆测序探究中性紫色土中活性氨氧化微生物群落组成.结果表明中性紫色土的净硝化速率为9.68mg·（kg·d）^-1，AOA和AOB在中性紫色土中均有较高的丰度且共同推动硝化作用的进行.系统发育分析结果表明培养初期（0d）在数量上占优势的AOB为Nitrosospira Cluster 3a.1，而Nitrosospira Cluster 3a.2只占较小的一部分，经过56d的培养后Nitrosospira Cluster 3a.2替代了Nitrosospira Cluster 3a.1成为主导氨氧化的活性AOB.培养初期（0d）在数量上占优势的AOA是Nitrososphaera Subcluster 9，但经过培养后变为Nitrososphaera Subcluster 3.2/3.3.在培养期间AOA和AOB的群落结构均发生了改变.对¹³C标记DNA的测序分析证明AOA和AOB在硝化过程中都起着重要作用，主导氨氧化的活性AOA和AOB主要分别隶属于Nitrososphaera Subcluster 3.2/3.3和Nitrosospira Cluster 3a.2.本研究明确了AOA及AOB对中性紫色土氨氧化过程的推动作用并从微生物层面探究硝化作用的发生机制，为进一步研究紫色土中硝化作用提供理论基础. 英文摘要 Increasing evidence suggests that ammonia oxidation in acidic soils is primarily catalyzed by ammonia-oxidizing archaea (AOA), while ammonia-oxidizing bacteria (AOB) drive ammonia oxidation in neutral and alkaline soils in which AOA overwhelmingly outnumber AOB. Therefore, neutral purple soil with a pH of 7.2 was selected to study the composition of the active ammoxidation microbial community with a stable isotope nucleic acid probe technique combined with cloning sequencing. Results showed that the nitrification rate was 9.68 mg·(kg·d)^-1, and AOA and AOB were abundant in neutral purple soils. By using DNA-based stable isotope probing (SIP), we gathered strong evidence of archaeal ammonia oxidation by AOA and AOB. Phylogenetic analysis indicated that the Nitrosospira Cluster 3a.1 AOB was dominant in terms of quantity at 0 days, and the Nitrosospira Cluster 3a.2 only accounted for a small part. After 56 days of cultivation, the Nitrosospira Cluster 3a.2 replaced the Nitrosospira Cluster 3a.1 as the active AOB that dominated ammonia oxidation. The AOA that predominated quantitatively at day 0 was Nitrososphaera Subcluster 9, but after cultivation this became Nitrososphaera Subcluster 3.2/3.3. Thus, the community structure of AOA and AOB changed. Active autotrophic nitrification was found in this neutral purple soil. Sequencing analysis of the ¹³C-labeled DNA provided robust evidence that both archaea and bacteria played important roles in the nitrification and not all ammonia oxidizers in native soil were active in the nitrification. Phylogenetic analysis clearly showed that the dominant active archaea and bacteria during the incubation were affiliated with Nitrososphaera Subcluster 3.2/3.3 within the soil group 1.1b lineage and Nitrosospira Cluster 3a.2, respectively, which were different from the dominant ammonia oxidizers at the beginning of the incubation. These results suggest that the community structure of ammonia oxidizers can shift quickly upon changes in the substrate availability in soils.

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