Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education, Zhejiang University, Hangzhou 310029, China.
Appl Environ Microbiol. 2011 Jul;77(13):4618-25. doi: 10.1128/AEM.00136-11. Epub 2011 May 13.
Ammonia oxidation is the first and rate-limiting step of nitrification and is performed by both ammonia-oxidizing archaea (AOA) and bacteria (AOB). However, the environmental drivers controlling the abundance, composition, and activity of AOA and AOB communities are not well characterized, and the relative importance of these two groups in soil nitrification is still debated. Chinese tea orchard soils provide an excellent system for investigating the long-term effects of low pH and nitrogen fertilization strategies. AOA and AOB abundance and community composition were therefore investigated in tea soils and adjacent pine forest soils, using quantitative PCR (qPCR), terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of respective ammonia monooxygenase (amoA) genes. There was strong evidence that soil pH was an important factor controlling AOB but not AOA abundance, and the ratio of AOA to AOB amoA gene abundance increased with decreasing soil pH in the tea orchard soils. In contrast, T-RFLP analysis suggested that soil pH was a key explanatory variable for both AOA and AOB community structure, but a significant relationship between community abundance and nitrification potential was observed only for AOA. High potential nitrification rates indicated that nitrification was mainly driven by AOA in these acidic soils. Dominant AOA amoA sequences in the highly acidic tea soils were all placed within a specific clade, and one AOA genotype appears to be well adapted to growth in highly acidic soils. Specific AOA and AOB populations dominated in soils at particular pH values and N content, suggesting adaptation to specific niches.
氨氧化作用是硝化作用的第一步和限速步骤，由氨氧化古菌（AOA）和细菌（AOB）共同完成。然而，控制氨氧化古菌和氨氧化细菌群落丰度、组成和活性的环境驱动因素尚未得到很好的描述，这两组群在土壤硝化作用中的相对重要性仍存在争议。中国茶园土壤为研究低 pH 值和氮肥管理策略对其长期影响提供了一个极好的系统。因此，采用定量 PCR（qPCR）、末端限制性片段长度多态性（T-RFLP）和氨单加氧酶（amoA）基因序列分析方法，研究了茶园土壤和相邻松林土壤中氨氧化古菌和氨氧化细菌的丰度和群落组成。有强有力的证据表明，土壤 pH 值是控制 AOB 但不控制 AOA 丰度的重要因素，而且在茶园土壤中，随着 pH 值的降低，AOA 与 AOB amoA 基因丰度的比值增加。相比之下，T-RFLP 分析表明，土壤 pH 值是 AOA 和 AOB 群落结构的关键解释变量，但仅在 AOA 中观察到群落丰度与硝化潜能之间存在显著关系。高硝化潜能表明，在这些酸性土壤中，硝化作用主要由 AOA 驱动。高度酸性茶园土壤中占主导地位的 AOA amoA 序列均属于特定的分支，一种 AOA 基因型似乎很好地适应了高度酸性土壤的生长。特定的 AOA 和 AOB 种群在特定 pH 值和 N 含量的土壤中占主导地位，表明它们适应于特定的生态位。
