The nitrogen cycle and the associated microbes play an important role in natural ecosystems, including terrestrial habitats; they also have a major effect on climate change. The aim of this study was to explore microbial communities in rice paddy soil by detecting and quantifying some key functional genes involved in the nitrogen cycle using molecular techniques such as conventional polymerase chain reaction (PCR), clone library construction, sequencing, phylogenetic analysis, and real-time PCR. The genes analyzed were as follows: nitrogenase reductase gene (nifH), hydrazine synthase gene (hzsA), nitrous oxide reductase gene (nosZ), copper-containing (nirK) and cytochrome cd1-containing (nirS) nitrite reductase genes, nitrite oxidoreductase gene (nxrB), and ammonium monooxygenase gene (amoA). The sequence assessment using the clone library targeting these genes revealed high diversity and dominance of bacterial communities. Furthermore, real-time PCR using SYBR green dye and some primers specific for each gene revealed the high abundance of nxrB (4.1 × 109 ± 0.4 × 109 copies g−1 soil) and low abundance of hzsA (4.0 × 105 ± 1.1 × 105 copies g−1 soil). The findings of our study will be useful to explore microbial communities in terrestrial habitats, such as agricultural paddy fields.

中文翻译：

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水稻土氮循环相关基因的功能多样性和丰富性

氮循环和相关的微生物在包括陆地生境在内的自然生态系统中起着重要作用；它们也对气候变化产生重大影响。这项研究的目的是通过使用常规聚合酶链反应（PCR），克隆文库构建，测序，系统发育分析和分子生物学等分子技术，通过检测和量化参与氮循环的一些关键功能基因，探索稻田土壤中的微生物群落。实时PCR。分析的基因如下：固氮酶还原酶基因（nifH），肼合酶基因（hzsA），一氧化二氮还原酶基因（nosZ），含铜（nirK）和含细胞色素cd1（nirS）的亚硝酸盐还原酶基因，亚硝酸盐氧化还原酶基因（nxrB）和铵单加氧酶基因（amoA）。使用针对这些基因的克隆文库进行的序列评估揭示了细菌群落的高度多样性和优势。此外，使用SYBR绿色染料和针对每个基因的一些特异性引物进行的实时PCR显示，nxrB的丰度很高（4.1×109±0.4×109拷贝g-1土壤）和hzsA的丰度较低（4.0×105±1.1×105）复制g-1土壤）。我们研究的结果将有助于探索陆地栖息地（例如农业稻田）中的微生物群落。