闽江河口互花米草不同入侵阶段湿地土壤nirK型反硝化微生物群落结构及多样性

为了明确闽江河口互花米草海向不同入侵阶段湿地土壤nirK型反硝化微生物的群落结构及多样性,在鳝鱼滩东部的互花米草分布区,由陆向海方向选择互花米草海向入侵前的光滩(MF)、入侵1～2年(SAN)和入侵6～7年的互花米草(SA)湿地为研究对象,基于高通量测序技术,测定并分析了不同互花米草入侵阶段湿地土壤nirK型反硝化微生物群落结构及多样性的差异。结果表明:互花米草海向入侵降低了土壤中nirK型反硝化微生物群落的多样性及丰富度。不同入侵阶段湿地土壤的nirK型反硝化微生物主要包括变形菌门和放线菌门,其中变形菌门占绝对优势地位。互花米草海向入侵整体改变了湿地土壤中nirK型反硝化菌属的组成特征,MF、SAN、SA湿地土壤中相对丰度最高的nirK基因菌属分别为慢生根瘤菌属、中慢生根瘤菌属和产碱杆菌属。互花米草海向入侵增加了土壤中nirK型反硝化微生物群落组成的空间异质性,尤其是在SAN样地,这主要与样地本身的环境扰动性较大及互花米草海向入侵加大了样地环境因子的空间异质性有关。互花米草海向入侵主要是通过显著改变土壤理化因子(粒度组成、pH值和含水量)和氮养分条件(全氮、NH₄⁺-N、NO₃^--N)来影响nirK型反硝化微生物的群落结构及多样性。本研究结果有助于揭示互花米草海向入侵对湿地土壤反硝化过程影响的微生物机制。

Structure and diversity of nirK-type denitrifying microbial community in marsh soils at different invasion stages of Spartina alterniflora in the Minjiang River estuary,China.

To explore the differences in structure and diversity of nirK-type denitrifying microbial community in marsh soils at different invasion stages of Spartina alterniflora, the mudflat (MF, before invasion) and the S. alterniflora marsh after seaward invasion for 1-2 years (SAN) and 6-7 years (SA) in Shanyutan of the Minjiang River estuary were investigated by high-through put sequencing method. Results showed that the seaward invasion of S. alterniflora reduced the richness and diversity of nirK-type denitrifying microbial community in marsh soils. The nirK-type denitrifying microbial community in soils at different invasion stages included Proteobacteria and Actinobacteria, with Proteobacteria as the dominant one. The seaward invasion of S. alterniflora greatly altered the composition of nirK-type denitrifying microbial community in marsh soils. The highest relative abundance of genus in soils from different invasion stages were Bradyrhizobium, Mesorhizobium and Alcaligenes, respectively. The seaward invasion of S. alterniflora increased the spatial heterogeneity of nirK-type denitrifying microbial community composition in marsh soils. In SAN plot, the enhancement of spatial heterogeneity was primarily due to higher environmental disturbances in plots and the increased spatial heterogeneity of environmental variables caused by the seaward invasion of S. alterniflora. The seaward invasion of S. alterniflora altered the physico-chemical properties (e.g., grain composition, pH and moisture) and N nutrient conditions (total N, NH₄⁺-N and NO₃^--N) in marsh soils, which greatly altered the structure and diversity of nirK-type denitrifying microbial community. Our findings reveal the microbial mechanism of denitrification process in marsh soils during the seaward invasion of S. alterniflora.