氮源添加对重金属污染土壤氨氧化微生物的影响

Variations on the Ammonia Oxidizers under Different Nitrogen Fertilization Regimes in Heavy Metal-contaminated Soil

矿业活动导致矿区土壤养分流失、土地退化,土壤生态系统敏感且脆弱,恢复过程复杂。其中土壤氮素缺乏是限制该生态系统恢复的主要因子之一。为探讨矿区土壤氮素恢复机制,以广西柳州泗顶矿区重金属污染土壤为研究对象,通过土壤培养实验,采用高通量测序结合荧光定量PCR技术,系统研究了氯化铵(38.114 g∙m^(-1)∙a^(-1)(高浓度)、9.54 g∙m^(-1)∙a^(-1)(低浓度))和尿素(21.43 g∙m^(-1)∙a^(-1)(高浓度)、5.36 g∙m^(-1)∙a^(-1)(低浓度))在不同添加频次(添加12次∙年-1(高频率)和2次∙年-1(低频率))下,对土壤氨氧化古菌(AOA)和氨氧化细菌(AOB)丰度、多样性和群落组成的影响。结果表明,各施氮模式下,amoA-AOB基因丰度显著高于amoA-AOA基因丰度,其丰度范围为(1.56×10^(7)±0.01×10^(7))-(3.58×10^(7)±0.03×10^(7))copies·g^(-1)(氯化铵)和(5.31×10^(7)±0.02×10^(7))-(14.85×10^(7)±0.04×10^(7))copies·g^(-1)(尿素)。AOA群落的ACE、Shannon和Simpson指数均值分别是AOB群落的13.2、1.41和0.627倍,AOA的α-多样性更容易受到不同施氮处理的影响。AOA在门水平上的优势菌门为奇古菌门(Thaumarchaeota)和泉古菌门(Crenarchaeota);在属水平上的优势菌属为亚硝基球菌属(Nitrososphaera)。AOB在门水平上的优势菌门为变形菌门(Proteobacteria);在属水平上的优势菌属为亚硝化螺菌属(Nitrosospira)和亚硝化弧菌属(Nitrosovibrio)。相关性分析表明土壤有效磷是影响amoA-AOB基因丰度的关键因素(p<0.01)。冗余分析表明,微生物量氮是引起AOA群落组成改变的主要因子;而土壤脲酶活性是引起AOB群落组成改变的主要因子。添加氯化铵和尿素使土壤氨氧化潜势和总硝化潜势增加,分别是对照的1.15-3.03倍和2.15-8.55倍,AOB主导土壤中的氨氧化和硝化过程。研究为明确矿区土壤氮循环变化规律,重建矿区土壤氮库提供了理论依据。

Mining activities lead to nutrient loss and land degradation in mining areas,where soil ecosystems are sensitive and fragile,making the restoration process complex and difficult.Among these limiting factors,nitrogen deficiency is a major obstacle to ecosystem recovery.To explore the mechanisms of nitrogen restoration in the soils of mining areas,this study focused on heavy metalcontaminated soils from the Siding Mining Area of Liuzhou,Guangxi.By conducting soil cultivation experiments and using highthroughput sequencing in combination with quantitative PCR technology,this study systematically investigated the effects of different application regimes of ammonium chloride(38.114 g∙m^(-1)∙a^(-1)(high concentration),9.54 g∙m^(-1)∙a^(-1)(low concentration)),and urea(21.43 g∙m^(-1)∙a^(-1)(high concentration),5.36 g∙m^(-1)∙a^(-1)(low concentration))with 12 times∙a^(-1)(high abundance)and 2 times∙a^(-1)(low abundance)added nitrogen on the abundance,diversity,and community composition of soil ammonia-oxidizing archaea(AOA)and ammoniaoxidizing bacteria(AOB).The results showed that the abundance of amoA-AOB gene was significantly higher than the abundance of amoA-AOA gene under different nitrogen application regimes,ranging from 1.56±0.01 to 3.58±0.03×10^(7)copies·g^(-1)(ammonium chloride)and 5.31±0.02 to 14.85±0.04×10^(7)copies·g^(-1)(urea).The average ACE,Shannon,and Simpson indices of the AOA community were 13.2,1.41,and 0.627 times higher,respectively,than those of the AOB community,suggesting that theα-diversity of AOA was more susceptible to different nitrogen treatments.The dominant phyla in AOA were Crenarchaeota,and Thaumarchaeota and the dominant genus was Nitrososphaera.For AOB,the dominant phylum was Proteobacteria and the dominant genera were Nitrospira and Nitrosovibrio.Correlation analysis showed that available phosphorus in the soil was a key factor affecting the abundance of amoAAOB gene.Redundancy analysis showed that nitrogen in microbial biomass was the main factor causing changes in AOA community composition,whereas urease activity in the soil was the main factor affecting changes in AOB community composition.The addition of ammonium chloride and urea increased the potential ammonia oxidation and total nitrification potential of the soil by 1.15-to 3.03-fold and 2.15-to 8.55-fold,respectively,compared with the control,with AOB dominating the ammonia oxidation and nitrification processes in the soil.This study provides a theoretical basis for clarifying the patterns of changes in the nitrogen cycle in the soils of mining areas and rebuilding the soil nitrogen pool.