花山流域小型水库氨氧化菌丰度和群落组成

Abundance and Community Composition of Ammonia-oxidizing Prokaryotes in the Small Reservoirs of Huashan Watershed

硝化在土壤氮循环中有着显著的作用,其中的第一步反应可以被氨氧化古菌(AOA)和氨氧化细菌(AOB)所催化。为了阐明湖泊沉积物营养水平差异对AOA和AOB丰度和多样性的影响,该研究采集了安徽省滁州市花山水文实验流域东源、中源和西源的3个小型水库表层沉积物样品,并测定不同沉积物样品中氮素的营养水平和氨氧化菌丰度和群落组成。结果表明,古菌的amo A基因丰度与p H以及总氮(TN)浓度呈现明显的正相关关系,细菌amo A基因OTUs数目明显正相关于p H以及TN,而古菌OTUs数目和NO3--N呈现一定正相关关系。采样点红旗水库沉积物中古菌amo A基因丰度最高(1.72×106拷贝/g干沉积物),而采样点狮子山坝的最低(1.51×105拷贝/g干沉积物)。不同沉积物样品细菌amo A基因丰度由大到小依次为龙库(2.11×108拷贝/g干沉积物)>狮子山坝(6.40×107拷贝/g干沉积物)>红旗水库(2.02×107拷贝/g干沉积物)。所有沉积物样品的细菌amo A基因丰度均高于古菌amo A基因丰度。古菌amo A基因序列分为两种属,即Nitrososphaera和Nitrosopumilus,细菌amo A基因主要有Nitrosomonas oligotropha,Nitrosospira,N.Europaea/Nc.mobilis和Undefined-N.Europaea/Nc.mobilis类群。p H和TN浓度对群落结构有重要影响。该研究获得的数据将利于更好的理解不同营养水平沉积物中的氨氧化过程的差异。

Nitrification plays a significant role in the global nitrogen cycling of which the f＇LrSt step can be catalyzed by ammonia-oxidizing archaea（AOA） and ammonia-oxidizing bacteria（AOB ）. Three sediment samples from Hongqi Reservoir, Shizishan Dam, Longku Reservoir were collected from eastern, central and western part of Huashan Watershed, Chuzhou, Anhui Province to determine the effects of nutrition level on the abundance and diversity of AOA and AOB. Results showed that the abundances of the archaeal amoA gene exhibited significantly positive correlations with pH and TN concentrations. OTUs number of the bacterial amoA gene was significantly positive related with pH and TN concentrations, whereas OTUs number of the archaeal amoA gene showed some positive correlation with NO3^--N concentrations. The archaeal amoA gene of Hongqi Reservoir was the highest as 1.72×10^6 g/dry sediment, whereas the lowest of which was found in Shizishan Dam as 1.51 ×10^5 g/dry sediment. The bacterial amoA gene in the different sediment samples followed the order of Longku Reservoir （2.11×10^7 g/dry sediment） 〉 Shizishan Dam （6.40×10^7 g/dry sediment） 〉 Hongqi Reservoir （2.02×10^7 g/dry sediment）. The abundance of bacterial amoA gene was higher than that of archaeal amoA gene in all sediment samples. Archaeal amoA gene sequences were divided into Nitrososphaera cluster and Nitrosopumilus cluster. The major of bacterial amoA sequences were Nitrosomonas oligotropha lineage, Nitrosospira lineage, N. Europaea/Nc.mobilis lineage and undefined-N. Europaea/Nc.mobilis lineage. The data obtained in the study is helpful to elucidate the nitrification process in sediments with different levels of nutrition in lake ecosystems.