中文摘要：

随着生物反应器和海洋生态系统中厌氧氨氧化反应的发现，自然生态系统的氮循环过程被重新认识，但是目前厌氧氨氧化过程是否也存在于富营养化湖泊湿地并发挥着重要作用，还未见报道。结合”N同位素示踪与分子生物学技术研究了白洋淀湖泊湿地沉积物中厌氧氨氧化菌的分布、菌群结构特性、生物多样性及其活性。结果表明，在藻类影响导致的高氨氮沉积物中，厌氧氨氧化菌具有广泛存在性。通过构建16SrRNA克隆文库发现，沉积物中厌氧氨氧化菌的生物多样性相对较低，在2％差异度的条件下，30个克隆序列只分为5个操作分类单元（OTUs），代表序列与Genebank数据库中已探明的厌氧氨氧化菌Candidatus Brocadia fulgida和Candidatus Brocadia anammoxidans同源性最高，分别可达97％和96％。同位素示踪结果表明，白洋淀湖泊湿地沉积物中厌氧氨氧化活性为0．19—7．78nmolNg-1h-1，空间差异较大，产生的氮气占此沉积物总氮气生成量的0．64％-20．65％，体现了湿地的异质性。通过得出的厌氧氨氧化反应速率推算每年由厌氧氨氧化反应损失的氮量为1．8—78gNm-2a-1，对白洋淀氮循环起到非常重要的作用。富营养化湖泊湿地沉积物中厌氧氨氧化反应的发现为研究厌氧氨氧化对氮循环的重要影响提供了新证据。

英文摘要：

Anaerobic ammonia oxidation （anammox） is one of the most innovative discoveries in field of microbial nitrogen cycle with its direct oxidation of ammonia to nitrogen gas with no N2O production. At present the anammox researches are limited to two areas：biological wastewater treatment and marine ecosystems. Evidence for anammox was obtained from Baiyangdian, the largest freshwater lake in North China, using an isotope pairing technique and molecular analysis. This lake is characterized by hyper-eutrophie conditions with a great amount of accumulated ammonia nitrogen （95--336 mg/kg） in surface sediments （0--5cm）. The anammox processes were detected on an extensive spatial scale （n = 10） in the lake sediments by PCR and 16S rRNA gene clone libraries, using primers combination pla46f-630r and Amx368f-Amx820r. The 30 sequences sharing 98% similarity were grouped into only five operational taxonomic unit （OTU） using software DOTUR by the furthest neighbor approach. The biodiversity indicator ＂ Shannon （ 1.4 ） and Chao 1 estimator （ 5 ） ＂ were also calculated with DOTUR software. The result of biodiversity analysis showed that anammox bacteria biodiversity in the lake sediments was low. Phylogenetic trees were constructed by neighbor-joining （NJ） with the Jukes-Cantor correction in MEGA 4 package. The 16S rRNA gene sequences of anammox bacteria in the surface sediments were closely related to the known anammox bacteria Candidatus Brocadia fulgida （ 97% ） and Candidatus Brocadia anammoxidans （ 96% ） , and it revealed most of anammox bacteria from Baiyangdian Lake may belong to ＂Brocadia＂. Isotope analyses were based on 15N labeled ammonium and nitrate. Three treatments （ 1 ） 15NH4 （ negative control） （2）15NH4 and 14NO3- （ positive control） （3） ln NH4 and 15N03（ test group） was prepared and experiments were operated in hermetic anaerobic containers at 19℃. Outcome gaseous N2 was delivered to Gas chromatography-isotope ratio mass spectrometry for s