Graduate School of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, Japan.
Microbes Environ. 2010;25(1):28-35. doi: 10.1264/jsme2.me09179.
Seasonal change in the vertical distribution of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in temperate forest soil was examined from March 2008 to January 2009 by quantitative PCR of the amoA genes. Abundances of AOA amoA genes (ranging from 2.0×10(8) to 1.2×10(9) copies per gram dry soil) were significantly higher than those of AOB amoA genes (1.9×10(5) to 1.7×10(7) copies). A significant increase in AOB was observed at a depth of 0-5 cm in July when net nitrification was also high in the top soil, while AOA increased significantly at depths of 5-10 cm, 10-15 cm, and over 15 cm in July. Sequencing of the crenarchaeotal amoA gene revealed shifts in major AOA components along the soil depth profile and among sampling dates. Betaproteobacterial amoA clone libraries at 0-5 cm in March, May, and July were dominated by Nitrosospira clusters 1 and 4. A microcosm experiment at 0-5 cm in July revealed a decrease in the ratio of AOA/AOB amoA genes in microcosms. These results suggest that AOB play an important role in net nitrification in the top layer in temperate forest soil.
从 2008 年 3 月到 2009 年 1 月，通过定量 PCR 检测 amoA 基因，研究了温带森林土壤中氨氧化古菌（AOA）和氨氧化细菌（AOB）的垂直分布季节性变化。AOA amoA 基因的丰度（范围为 2.0×10(8) 到 1.2×10(9) 拷贝/克干土）明显高于 AOB amoA 基因的丰度（1.9×10(5) 到 1.7×10(7) 拷贝）。7 月，当表土中的净硝化作用也很高时，AOB 在 0-5 厘米深度处的数量显著增加，而 AOA 在 7 月的 5-10 厘米、10-15 厘米和 15 厘米以上深度处的数量显著增加。对泉古菌 amoA 基因的测序显示，主要 AOA 成分沿土壤深度剖面和采样日期发生了变化。3 月、5 月和 7 月 0-5 厘米处的β变形菌 amoA 克隆文库主要由硝化螺旋菌簇 1 和 4 组成。7 月 0-5 厘米处的微宇宙实验表明，微宇宙中 AOA/AOB amoA 基因的比值下降。这些结果表明，AOB 在温带森林土壤表层的净硝化作用中发挥了重要作用。
