农业废物好氧堆肥中环境因子对nirK、nirS和nosZ数量的影响

应用定量聚合酶链式反应(real-time PCR)技术对农业废物好氧堆肥过程中参与反硝化过程的功能基因(nirK、nirS和nosZ)丰度在堆体不同位置处随时间的变化情况进行了研究.结果表明,随着堆肥进程,3种基因数量整体呈现出先升后降的变化规律,且不同位置处的反硝化基因数量之间存在着显著的差异性.使用Canoco 4.5软件对获得的反硝化功能基因丰度数据与不同时期不同层次堆体温度、pH、含水率、NH4+-N、NO3--N和水溶性有机碳(WSC)等环境因子的相关性进行冗余分析(redundancy analysis,RDA).基于手动选择的RDA分析结果表明,WSC、NH4+-N和堆体温度对反硝化基因丰度有着显著的影响(P<0.05),且前2个因子达到了极显著水平(P<0.01).应用t-value回归分析方法单独分析每种环境因子与3种基因的相关性,其中nirK与温度和pH显著正相关(P<0.05),nirS与温度显著正相关(P<0.05),nosZ与NH4+-N显著正相关(P<0.05)、与WSC显著负相关(P<0.05).

Effects of Physico-chemical Parameters on the Abundance of the Denitrification-associated Genes nirK, nirS and nosZ During Agricultural Waste Composting

The abundance variation of the functional genes (nirK, nirS and nosZ) involved in denitrification was investigated using the real-time polymerase chain reaction (real-time PCR) at different locations (top, center and bottom) of the compost pile during the agricultural waste composting. The changes in pile temperature, pH, moisture content, soluble NH₄⁺-N, NO₃^--N and water soluble carbon (WSC) were measured. The results showed that the abundance of those genes varied among the samples collected in different zones. Redundancy analysis (RDA) was applied to explore the correlations between the abundance of nirK, nirS and nosZ and the composting physic-chemical parameters. The results suggested that water soluble carbon (WSC), pile temperature and nitrate had the most significant impacts on the abundance of the three genes. The t-value biplots for each environmental variable indicated that nirK was positively related with temperature and pH (P<0.05), nirS was positively related with temperature (P<0.05), and nosZ was positively related with NH₄⁺-N while negatively with WSC.