旱地作物根际和非根际土壤硝酸盐异化还原成铵细菌群落组成的研究

为研究典型旱地农田土壤硝酸盐异化还原成铵过程(Dissimilatory nitrate reduction to ammonium,DNRA)的群落组成,针对DNRA过程的功能基因nrfA进行高通量测序.根际和非根际、4种典型农作物共16个样品,质控后每个样品得到87000条序列,在相似度≥90%下划分到27952个OTUs,选取其中丰度较高的258个代表OTUs进行生态学分析.多样性分析(OTUs水平)结果表明:3/4的作物根际土壤样品中的DNRA群落丰富度、物种多样性和物种均匀度高于相应非根际样品,对比4种作物,粟作物根部土壤DNRA群落多样性最高,玉米作物非根际土壤最低.对代表OTUs进行分类,共定义到6个门(Phylum),19个属(Genus).其中相对丰度最高的3个属为Hyalangium(29.31%)、Chthoniobacter(20.33%)和Nitrospira(13.41%),表明三者在群落组成中占主导地位.结合土壤理化因子分析,DNRA群落相对丰度与NO~-_2-N、TN、含水率、TOM、pH及温度呈显著相关关系.本研究在一定程度上揭示了旱地农田土壤DNRA细菌的群落组成、多样性及与土壤环境因子的关系,为提高氮肥的利用效率和减小环境污染提供理论依据.

Community composition of dissimilatory nitrate reduction to ammonium (dnra) bacteria in rhizosphere and non-rhizosphere soil of agricultural lands

To explore the community composition of dissimilatory nitrate reduction to ammonium (DNRA) process in typical agricultural dryland soil, high-throughput sequencing targeting on the functional gene nrfA of DNRA bacteria was carried out. A total of 16 samples of rhizosphere and non-rhizosphere soils from 4 typical agricultural lands were collected, and 87000 sequences were obtained for each sample after quality control. Then these sequences were clustered to 27952 OTUs with similarity above 90%, of which 258 representative OTUs with higher abundance were selected for community analysis. Results of diversity analysis (OTUs level) demonstrated that 3/4 of the samples in rhizosphere soil had a higher diversity, richness, and species uniformity of DNRA community than those in the corresponding non-rhizosphere soils. Moreover, it was found that rhizosphere soil of millet crops had the highest diversity of DNRA community while non-rhizosphere soil of maize crops had the lowest one among the investigated crops. Furthermore, the representative OTUs was classified into 6 phyla and 19 genera, and, the three highest richness genera were Hyalangium (29.31%), Chthoniobacter (20.33%) and Nitrospira (13.41%), indicating their dominant role in DNRA community composition. Combined with soil physicochemical factor analysis, the relative abundance of DNRA community was significantly correlated with NO₂^--N, TN, moisture content, TOM, pH and temperature in the four crops. To some extent, this study revealed the community composition, diversity of DNRA bacteria, and their relationship with soil environmental factors in agricultural dryland soil, providing theoretical basis for improving the utilization efficiency of nitrogen fertilizer and reducing environmental pollution.