Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse, D-35043, Marburg, Germany.
Environ Microbiol. 2009 Jul;11(7):1658-71. doi: 10.1111/j.1462-2920.2009.01891.x. Epub 2009 Feb 19.
Agricultural ecosystems annually receive approximately 25% of the global nitrogen input, much of which is oxidized at least once by ammonia-oxidizing prokaryotes to complete the nitrogen cycle. Recent discoveries have expanded the known ammonia-oxidizing prokaryotes from the domain Bacteria to Archaea. However, in the complex soil environment it remains unclear whether ammonia oxidation is exclusively or predominantly linked to Archaea as implied by their exceptionally high abundance. Here we show that Bacteria rather than Archaea functionally dominate ammonia oxidation in an agricultural soil, despite the fact that archaeal versus bacterial amoA genes are numerically more dominant. In soil microcosms, in which ammonia oxidation was stimulated by ammonium and inhibited by acetylene, activity change was paralleled by abundance change of bacterial but not of archaeal amoA gene copy numbers. Molecular fingerprinting of amoA genes also coupled ammonia oxidation activity with bacterial but not archaeal amoA gene patterns. DNA-stable isotope probing demonstrated CO(2) assimilation by Bacteria rather than Archaea. Our results indicate that Archaea were not important for ammonia oxidation in the agricultural soil tested.
农业生态系统每年接收大约全球氮输入的 25%，其中大部分至少被氨氧化原核生物氧化一次，以完成氮循环。最近的发现将已知的氨氧化原核生物从细菌扩展到古菌。然而，在复杂的土壤环境中，氨氧化是否仅与古菌相关联，或者像它们异常高的丰度所暗示的那样占主导地位，这一点尚不清楚。在这里，我们表明，尽管古菌氨单加氧酶（amoA）基因在数量上比细菌更占优势，但在农业土壤中，细菌在功能上主导氨氧化，而不是古菌。在土壤微宇宙中，氨氧化受到铵的刺激和乙炔的抑制，活性的变化与细菌而非古菌 amoA 基因拷贝数的丰度变化相平行。amoA 基因的分子指纹图谱也将氨氧化活性与细菌而非古菌 amoA 基因模式联系起来。DNA 稳定同位素探测表明 CO2 被细菌同化，而不是古菌。我们的结果表明，在测试的农业土壤中，古菌对氨氧化不重要。
