石灰性紫色水稻土不同土壤深度中厌氧氨氧化细菌对施肥的响应

Response of Anammox Bacteria Community Structure and Vertical Distribution to Different Long-Term Fertilizations in Calcareous Purple Paddy Soil

【目的】研究长期不同施肥处理对水稻土厌氧氨氧化细菌(anaerobic ammonium oxidation bacteria,AAOB)群落结构和垂直分布特征的影响,深入认识不同施肥处理下石灰性紫色水稻土厌氧氨氧化作用的微生物调控机制,为该地区科学施肥、培肥地力提供理论依据。【方法】利用化学分析、末端限制性片段长度多态性分析(T-RFLP)和荧光定量PCR技术分别对不同施肥处理下石灰性紫色水稻土理化性质、厌氧氨氧化细菌丰度及群落结构进行分析。【结果】理化性质结果显示,相对于无肥处理(CK),氮(N)、氮磷钾肥(NPK)及氮磷钾配施农家肥(NPKM)均会降低土壤p H和硝态氮含量,而增加土壤有机质、全氮和铵态氮含量。随土壤深度增加,土壤p H增加,全氮和硝态氮含量降低,铵态氮含量变化趋势不明显。q PCR结果显示,就土壤层次而言,厌氧氨氧化细菌在0—20 cm层的丰度最高,20—40 cm层最低;就施肥处理而言,氮肥(N)对厌氧氨氧化细菌的丰度促进最为明显。T-RFLP结果表明,厌氧氨氧化细菌在0—20 cm土层群落组成最为丰富,Shannon-wiener多样性指数最高;寡氮肥下其群落组成最为简单,无肥处理下群落结构最为复杂。厌氧氨氧化细菌优势种群属于Candidatus Brocadia。冗余梯度分析(RDA)显示,p H影响是石灰性紫色水稻土厌氧氨氧化细菌群落结构差异的主要环境因子。【结论】本研究显示寡氮处理会降低石灰性紫色水稻土中厌氧氨氧化细菌的多样性但促进其丰度。表层土(0—20 cm)是厌氧氨氧化细菌分布的主要层次。

[Objective]The impacts of long-term fertilizations on the anaerobic ammonium oxidation bacteria （AAOB） community structure and vertical distribution were studied in order to deeply understand the microbial mediated mechanism of anammox reaction, develop a sound fertilization regime and provide theoretical foundations for maintaining the soil quality in this region.[Method]Chemical analysis, real-time PCR and terminal restriction fragment length polymorphism （T-RFLP） were used to analyze the soil physico-chemical properties, the 16S rRNA gene abundance and composition of AAOB community, respectively.[Result]The results showed that compared to no fertilizer application control （CK）, all fertilizers decreased the soil pH and nitrate content, while increased soil organic matter （SOM）, total nitrogen （TN） and ammonia content. With increasing of soil depth, soil parameters including soil pH, TN, and nitrate content were decreased, while the ammonia content was not obviously changed. The qPCR results showed： the abundance of AAOB 16S rRNA gene peaked in the 0-20 cm layer, while being the lowest in the 20-40 cm depth. Mere nitrogen treatment （N） had an evident positive effect on the abundance of AAOB. The T-RFLP results indicated that in the 0-20 cm layer, the community compositions of AAOB were the most complex, which were also supported by the highest Shannon-wiener diversity index. Compositions of AAOB community in the soil fertilized with N only were the simplest, while those in the soil amended with CK were the richest. Besides, the predominant AAOB were phylogenetically affiliated to Candidatus Brocadia. Redundant gradient analysis （RDA） showed that pH was the key factor in shaping the AAOB community in calcareous purple paddy soil amended with different fertilizer treatments.[Conclusion]This study suggested that mere N fertilizer would decrease the compositions of AAOB community in calcareous purple paddy soil but increase their abundances. The topsoil （0-20 cm） was the main distribution soil depth in calcareous purple paddy soil for AAOB.