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Nitrous oxide reduction is a pivotal process of nitrogen transformation regarding to global warming and ozone depletion, but little is known about the ecological distribution of nitrous oxide reducing communities and their determining factors. In total, 131 agricultural upland soil samples, including quaternary red clay soil (QRC), tertiary red stone soil (TRS), alluvial soil (AS) and black soil (BS) were collected in this study. Typical nitrous oxide reducers (nosZI) were sequenced on an Illumina Miseq platform. The results showed that although different types of soils displayed distinctive soil properties, 515 out of 994 OTUs were common species shared by all the four soil types, moreover, these common OTUs took 96-99% of the relative abundance of the total nosZI-containing population in different soil types. In contrast, unique nosZI-containing species which appeared in one specific type of soil were minimal. Furthermore, copiotrophic taxa including Bradyrhizobiaceae, Rhodospirillaceae and Phyllobacteriaceae were the dominant common nosZI-containing communities. These results indicated that nosZI-containing denitrifiers were homogenously distributed among different agricultural soils, which may be closely related to the intensive agricultural practices under long-term crop cultivation. Even though, the relative abundance of most of the common OTUs, especially the high abundant ones, showed significant variations among the soil types.

Collectively, our results suggested that the nosZI-containing soil microorganisms could be homogenized and enriched in agricultural soils with the agricultural practices acting as major potential drivers, whereas soil distinctive properties resulted in significant shifts in the relative abundance of common nosZI-containing denitrifying species and the presence of a small number of unique communities with low abundance.