Pouliot Jérémie, Galand Pierre E, Lovejoy Connie, Vincent Warwick F
Département de Biologie and Québec-Océan, Université Laval, Québec, QC, Canada.
Environ Microbiol. 2009 Mar;11(3):687-99. doi: 10.1111/j.1462-2920.2008.01846.x. Epub 2009 Jan 15.
The distribution of archaeal amoA and 16S rRNA genes was evaluated in two marine-derived, meromictic lakes in the Canadian High Arctic: Lake A and Lake C1 on the northern coast of Ellesmere Island. The amoA gene was recorded in both lakes, with highest copy numbers in the oxycline. Sequence analysis showed that amoA from the two lakes shared 94% similarity, indicating at least two phylogenetically distinct clusters. Clone libraries of archaeal 16S rRNA genes from Lake A revealed strong vertical differences in archaeal community diversity and composition down the water column. The oxic layer was dominated by one group of Euryarchaeota affiliated to the Lake Dagow Sediment (LDS) cluster. This group was absent from the oxycline, which had an extremely low archaeal diversity of two phylotypes. Both belonged to the Crenarchaeota Marine Group I (MGI), the marine group that has been linked to archaeal amoA; however, there was a low ratio of amoA to MGI copy numbers, suggesting that many MGI Archaea did not carry the amoA gene. The anoxic zone contained representatives of the RC-V (Rice Cluster-V) and LDS clusters of Euryarchaeota. These results show the strong vertical differentiation of archaeal communities in polar meromictic lakes, and they suggest archaeal nitrification within the oxycline of these highly stratified waters.
在加拿大北极地区的两个海洋成因的半咸水湖（埃尔斯米尔岛北海岸的A湖和C1湖）中评估了古菌amoA和16S rRNA基因的分布。在两个湖中均检测到amoA基因，在氧化还原cline中拷贝数最高。序列分析表明，来自两个湖的amoA具有94%的相似性，表明至少有两个系统发育上不同的簇。来自A湖的古菌16S rRNA基因克隆文库显示，水柱中古菌群落多样性和组成存在强烈的垂直差异。好氧层由一组隶属于达戈湖沉积物（LDS）簇的广古菌门主导。该组在氧化还原cline中不存在，氧化还原cline中古菌多样性极低，只有两个系统发育型。两者都属于泉古菌门海洋第一类群（MGI），该海洋类群与古菌amoA有关；然而，amoA与MGI拷贝数的比率较低，表明许多MGI古菌不携带amoA基因。缺氧区包含广古菌门的RC-V（水稻簇-V）和LDS簇的代表。这些结果表明极地半咸水湖中古菌群落存在强烈的垂直分化，并表明在这些高度分层水体的氧化还原cline内存在古菌硝化作用。
