人工湿地沟壕系统中硝酸盐异化还原成铵细菌群落特征研究

硝酸盐异化还原成铵（Dissimilatory nitrate reduction to ammonium,DNRA）过程,是将易损失的NO₃^--N转化为NH₄⁺-N,而被植物或微生物重新吸收利用,从而有助于湿地沉积物的氮保留.本研究选取石臼漾人工湿地冬、夏两季沟壕中心、边缘表层沉积物,采用高通量测序等分析方法,研究了DNRA细菌群落结构特征.研究结果表明：在空间尺度上,沟壕中心DNRA细菌丰度高于沟壕边缘,分别为（2.26±1.19）×10⁹和（1.22±1.46）×10⁹ copies·g^-1.在时间尺度上,冬夏两季样品中DNRA细菌丰度具有显著性差异（p<0.05）.多样性分析表明,沟壕中心沉积物的DNRA群落丰富度高于沟壕边缘.所有样品中占比最高的DNRA属为Caldilinea（69.75%±3.64%）、Anaeromyxobacter（66.41%±1.19%）.Caldilinea属在夏季样品的占比（39.78%±5.15%）高于冬季样品（29.98%±0.57%）,而Anaeromyxobacter属在沟壕中心的占比（35.14%±0.83%）高于沟壕边缘（31.28%±0.76%）,且小沟（34.33%±1.40%）高于大沟（32.08%±1.33%）.主坐标分析（PcoA）结果表明,DNRA细菌群落结构具有明显的时间异质性.DNRA细菌丰度与有机质（TOM）、碳氮比（C/N）和含水率（MC）显著相关.本研究揭示了人工湿地沉积物中DNRA细菌的丰度、群落组成、多样性及其与环境因子的关系.

Community characteristics of dissimilatory nitrate reduction to ammonium bacteria in ditch system of constructed wetland

Dissimilatory nitrate reduction to ammonium (DNRA) converts lossy NO₃^--N into NH₄⁺-N, which can be absorbed and utilized by plants or microorganisms, thus contributing to the retention of nitrogen in wetland sediments. In this study, the characteristics of DNRA bacterial community structure in the surface sediments of ditch center and edge of Shijiuyang constructed wetland in winter and summer were studied, using high-throughput sequencing technology. On the spatial scale, the results showed that the bacterial abundance of DNRA in the ditch center was higher than that in the ditch edge, which were (2.26±1.19)×10⁹ and (1.22±1.46)×10⁹ copies·g^-1, respectively. On a time scale, there was significant difference of DNRA bacterial abundance between winter and summer (p<0.05). The results of diversity analysis showed that the richness of DNRA community in the center sediment of the ditch was higher than that in the ditch edge. The highest proportions of DNRA in all the samples were Caldilinea (69.75%±3.64%) and Anaeromyxobacter (66.41%±1.19%). The percentage of Caldilinea in summer (39.78%±5.15%) was higher than that in winter (29.98%±0.57%), while the percentage of Anaeromyxobacter in the ditch center (35.14%±0.83%) was higher than that in the ditch edge (31.28%±0.76%), and the percentage of small ditch (34.33%±1.40%) was higher than that of large ditch (32.08%±1.33%). Principal coordinate analysis (PCoA) shows that the bacterial community structure of DNRA has obvious time heterogeneity. The bacterial abundance of DNRA is significantly correlated with total organic matter (TOM), C/N and moisture content (MC). To summarize, this study reveals the abundance, community composition and diversity of DNRA bacteria and their relationships with environmental factors in constructed wetland sediments.