Recent studies demonstrated that phylogenetically more diverse and abundant bacteria and fungi than previously considered are responsible for denitrification in terrestrial environments. We herein examined the effects of land-use types on the community composition of those denitrifying microbes based on their nitrite reductase gene (nirK and nirS) sequences. These genes can be phylogenetically grouped into several clusters. We used cluster-specific PCR primers to amplify nirK and nirS belonging to each cluster because the most widely used primers only amplify genes belonging to a single cluster. We found that the dominant taxa as well as overall community composition of denitrifying bacteria and fungi, regardless of the cluster they belonged to, differed according to the land-use type. We also identified distinguishing taxa based on individual land-use types, the distribution of which has not previously been characterized, such as denitrifying bacteria or fungi dominant in forest soils, Rhodanobacter having nirK, Penicillium having nirK, and Bradyrhizobium having nirS. These results suggest that land-use management affects the ecological constraints and consequences of denitrification in terrestrial environments through the assembly of distinct communities of denitrifiers.

中文翻译：

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不同土地利用类型中先前未表征的反硝化细菌和真菌的独特群落组成

最近的研究表明，在系统发育上，比以前认为的更加多样化和丰富的细菌和真菌是陆地环境反硝化的原因。我们在此根据亚硝酸盐还原酶基因（nirK 和 nirS）序列研究了土地利用类型对这些反硝化微生物群落组成的影响。这些基因可以在系统发育上分为几个簇。我们使用簇特异性 PCR 引物来扩增属于每个簇的 nirK 和 nirS，因为最广泛使用的引物仅扩增属于单个簇的基因。我们发现，反硝化细菌和真菌的主要类群以及总体群落组成，无论它们属于哪个簇，都会根据土地利用类型的不同而有所不同。我们还根据各个土地利用类型确定了不同的分类群，其分布以前尚未被表征过，例如森林土壤中占优势的反硝化细菌或真菌、具有 nirK 的红细菌、具有 nirK 的青霉属和具有 nirS 的慢生根瘤菌。这些结果表明，土地利用管理通过不同反硝化菌群落的聚集，影响陆地环境中反硝化的生态约束和后果。