滨海盐渍化土壤中氨氧化微生物丰度和多样性特征

Patterns of Activity and Community of Ammonia Oxidizers Along Salinity Gradient in Salinized Soils

为探究滨海盐土不同盐度梯度下氨氧化微生物的丰度和多样性特征,利用土壤化学和分子生态学手段(定量PCR、T-RFLP)对莱州湾南岸及黄河口4个河口断面(黄河、白浪河、堤河、胶莱河)14个不同盐度(6.4‰~51.1‰)盐渍化土壤样品的氨氧化古菌(AOA)和氨氧化细菌(AOB)的硝化潜势、丰度及多样性进行了分析。结果发现:土壤硝化潜势在高盐度(34.7‰~51.1‰)条件下被显著抑制,主要受土壤盐度、p H和NO3–-N水平显著影响;AOA-amoA基因丰度比AOB-amoA高出两个数量级,在中盐度时丰度最高(9.92×106copies/g土),在高盐度时受到显著抑制(5.28×106copies/g土,P<0.05);AOB-amoA基因丰度受盐度的影响,低盐度时显著高于中、高盐度条件;然而AOA和AOB的多样性和群落结构受盐度梯度影响不大。相关分析表明,硝化潜势与AOA和AOB丰度均无显著相关性,而与AOA/AOB比值以及AOA的Shannon指数显著负相关。由此可见,滨海盐土中,盐度的波动对土壤氨氧化活性和功能微生物都会产生剧烈的影响,盐度和p H造成的土壤氮素有效性的变化可能是影响滨海盐土硝化活性和氨氧化微生物丰度及群落组成的关键因素。

To explore the effects of the salinity gradient on the abundance and diversity of ammonia-oxidizing microorganisms in coastal salinized soils,salinized soil samples with different salinities (6.4‰–51.3‰) were collected from four estuary transects(Yellow River,Bailang River,Di River,and Jiaolai River) in the southwest coast of Laizhou Bay.The methods of soil chemistry and molecular ecology (qPCR and T-RFLP) were applied to analyze the activities,abundance and community structures of ammonia-oxidizing archaea (AOA) and bacteria (AOB).The results showed that soil nitrification potential (NP) was significantly inhibited at high salinity (34.7‰–51.3‰) and it was significantly correlated with soil salinity,pH,and NO3–-N level.Abundance of AOA-amoA gene was two orders of magnitude higher than that of AOB-amoA gene,which was highest at medium salinity(9.92×10~6 copies/g soil),and was inhibited at high salinity (5.28×10~6 copies/g soil,P<0.05).Abundance of AOB-amoA was correlated with soil salinity,which was highest at low salinity and significantly reduced at medium and high salinities.However,the diversities and community structures of both AOA and AOB were little affected by the salinity gradient based on the T-RFLP data.Furthermore,correlation analysis showed that NP was not significantly correlated with abundance of AOA or AOB,but negatively significantly correlated with the ratio of AOA/AOB and the Shannon index of AOA.In conclusion,the ammonia oxidation activity and its functional microorganisms in coastal saline soils were affected intensively by the fluctuation of salinity The changes of soil nitrogen availability caused by salinity and pH may be the key factors affecting nitrification activity microbial abundance and community composition in coastal saline soils.