稻田土壤厌氧氨氧化菌群落结构对长期不同施肥的响应

Response of Paddy Soil Anammox Bacteria to Long-Term Fertilization in Community Structure

研究长期不同施肥稻田土壤厌氧氨氧化微生物丰度和群落结构组成,深入认识稻田厌氧氨氧化菌对不同施肥的响应机理,可为合理施肥和理解湿地生态系统厌氧氨氧化过程提供科学依据。设置不施肥(CK)、单施无机肥(NPK)、无机肥配施牛粪(NPKM)、无机肥加秸秆还田(NPKS)四个处理,采用荧光定量PCR和高通量测序对不同施肥模式下水稻土厌氧氨氧化细菌丰度和群落结构进行分析。结果发现,不同处理之间厌氧氨氧化细菌丰度具有显著差异(p<0.05),表现为NPKM>NPKS>NPK>CK,且与有机质、全氮和铵态氮含量具有显著相关性(p<0.05)。高通量测序结果表明,不同施肥处理主要的厌氧氨氧化菌为Candidatus Brocadia、Candidatus Anammoxoglobus和Candidatus Scalindua,其中优势种群为Candidatus Brocadia。菌群的多样性分析表明,CK和NPKS处理的厌氧氨氧化菌群落结构多样性香农指数(Shannon index)、辛普森指数(Simpson index)和丰富度指数(Chao 1 index)显著高于NPKM和NPK处理(p<0.05)。上述结果表明,长期施肥改变了厌氧氨氧化菌的数量和群落结构。有机无机肥配施更有利于提高厌氧氨氧化菌丰度。然而,不同施肥措施对厌氧氨氧化菌的多样性影响不同,无机肥加秸秆还田提高了厌氧氨氧化菌多样性,但单施无机肥和无机肥配牛粪降低了厌氧氨氧化菌多样性。厌氧氨氧化菌的数量和群落结构对不同施肥的响应不同。

【Objective】 This study was conducted to investigate abundance and community structure of anaerobic ammonia oxidizing（anammox） bacteria in paddy soils under long-term fertilization and explore mechanism of anammox bacteria responding to different fertilizers, in an attempt to provide a scientific basis for rationalizing fertilization and understanding ammonia oxidizing processes in wetland ecosystems. 【Method】 Four treatments, i.e. control（CK）, chemical fertilizer（NPK）, chemical fertilizer plus cattle manure（NPKM）, and chemical fertilizer plus straw（NPKS）, were set in the field experiment of the study. Soil samples were collected from the treatments for analysis of abundance and community structure of soil anammox bacteria, using the fluorescent quantitative PCR assay targeting hydrazine synthase α-subunit（hzs A） gene and high-throughput sequencing technology aiming at 16S rRNAgene of anammox bacteria. 【Result】Significant differences were observed between the treatments in abundance of hzs A gene（p〈0.05）, exhibiting an order of NPKM〉NPKS〉NPK〉CK. Correlation analysis（p〈0.05） shows that abundance of hzs A gene was significantly and positively related to soil organic matter, total nitrogen and ammonia content. High-throughput sequencing shows Candidatus Brocadia, Candidatus Anammoxoglobus and Candidatus Scalindua were the main anammox bacteria and Candidatus Brocadia the dominant one in all the treatments. Bacteria diversity analysis shows that treatments CK and NPKS were significantly higher than treatment NPKM and NPK in Shannon index, Simpson index and Chao 1 index（p〈0.05）. 【Conclusion】 Long-term fertilization alters the anammox bacteria community in population and structure. The application of chemical fertilizers combined with organic manure is conducive to abundance of the anammox bacteria. However, the anammox bacteria community in the soil varies in structure with difference in fertilization. The anammox bacteria community increased in α-diversity in the soil applied with chemical fertilizer plus straw, but decreased in the soil applied with chemical fertilizer only and chemical fertilizer plus cattle manure. It can, therefore, be concluded that anammox bacteria vary in their response to different fertilizer or manure used in abundance and community structure.