Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha, P. R. China; Graduate School of the Chinese Academy of Sciences, Beijing, P. R. China; Huanjiang Observation and Research Station for Karst Eco-Systems, Huanjiang, P. R. China.
J Basic Microbiol. 2014 Mar;54(3):180-9. doi: 10.1002/jobm.201300217. Epub 2013 Jul 30.
Soil ammonia oxidizers play a critical role in nitrogen cycling and ecological restoration. The composition and structure of soil ammonia oxidizers and their impacting factors were studied in four typical ecosystem soils, tussock (T), shrub (S), secondary forest (SF), and primary forest (PF), during vegetation restoration in the Karst region of Southwest China. The composition and structure of the ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) communities were characterized by sequencing the amoA and arch-amoA genes, respectively. The diversity of soil ammonia oxidizers (except in S) and plant Shannon diversity index gradually increased with vegetation restoration, and the ammonia oxidizer communities differed significantly (p < 0.001). Amplicons of AOA from the Nitrososphaera cluster dominated all four ecosystem soils. AOB Nitrosospira cluster 3b only appeared in PF and SF soils, while Nitrosospira cluster 3a species were found in all soils. Changes in AOB paralleled the changes in soil ammonium content that occurred with vegetation restoration. Redundancy analysis showed that the distribution of dominant AOB species was linked to pH, soil urease activity, and soil C/N ratio, whereas the distribution of dominant AOA species was mainly influenced by litter nitrogen content and C/N ratio. These results suggested that the composition and structure of the AOB community were more sensitive to changes in vegetation and soil ammonium content, and may be an important indicator of nitrogen availability in Karst ecosystem soils.
土壤氨氧化微生物在氮循环和生态恢复中起着关键作用。本研究采用测序技术，分别对氨氧化细菌（AOB）和氨氧化古菌（AOA）amoA 基因进行分析，研究了中国西南喀斯特地区植被恢复过程中，草地（T）、灌丛（S）、次生林（SF）和原始林（PF）4 种典型生态系统土壤中氨氧化微生物的组成和结构及其影响因素。结果表明，除灌丛土壤外，土壤氨氧化微生物多样性（除灌丛土壤外）和植物 Shannon 多样性指数随植被恢复逐渐增加，氨氧化微生物群落差异显著（p < 0.001）。所有生态系统土壤的氨氧化微生物群落均以硝化螺旋菌属（Nitrososphaera）为主导。PF 和 SF 土壤中仅出现亚硝化螺菌属（Nitrosospira）clade 3b，而所有土壤中均存在亚硝化单胞菌属（Nitrosomonas）clade 3a 种。AOB 的变化与植被恢复过程中土壤铵含量的变化相一致。冗余分析表明，优势 AOB 物种的分布与 pH、土壤脲酶活性和土壤 C/N 比有关，而优势 AOA 物种的分布主要受凋落物氮含量和 C/N 比的影响。这些结果表明，AOB 群落的组成和结构对植被和土壤铵含量的变化更为敏感，可能是喀斯特生态系统土壤氮素有效性的重要指标。
