Thaumarchaeal Ammonia Oxidation in an Acidic Forest Peat Soil Is Not Influenced by Ammonium Amendment

摘要: Both bacteria and thaumarchaea contribute to ammonia oxidation, the first step in nitrification. The abundance of putative oxidizers is estimated by quantification functional gene amoA, which encodes monooxygenase subunit A. In soil, thaumarchaeal amoA genes often outnumber equivalent bacterial genes. Ecophysiological studies indicate that may have a selective advantage at low concentrations, with potential adaptation soils mineralization major source ammonia. To test this hypothesis, were investigated during nitrification microcosms containing an organic, acidic forest peat soil (pH 4.1) ammonium concentration but high for release mineralization. Net rates not influenced addition ammonium. Bacterial could be detected, presumably because oxidizers. Phylogenetic analysis 16S rRNA sequences indicated dominant populations belonged group 1.1c, 1.3, "deep peat" lineages, while known amo-containing lineages (groups 1.1a 1.1b) comprised only small proportion total community. Growth was increased unaffected Similarly, denaturing gradient gel electrophoresis transcripts demonstrated temporal changes oxidizer communities no effect amendment. Thaumarchaea therefore appeared dominate oxidation oxidized arising from organic matter rather than added inorganic nitrogen.