Vertical structure of archaeal communities and the distribution of ammonia monooxygenase A gene variants in two meromictic High Arctic lakes

• Published in: Environmental Microbiology
• Main Authors: Pouliot, J., Galand, Pierre E., Lovejoy, Connie, Vincent, Warwick F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing 2009
• Subjects: Arctic; Arctic Lake; Canada; Ellesmere Island; ArcticNet; Quttinirpaaq National Park
• Online Access: http://hdl.handle.net/10261/57614; https://doi.org/10.1111/j.1462-2920.2008.01846.x

13 páginas, 3 tablas, 6 figuras. 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. We acknowledge the financial assistance from ArcticNet (a Canadian Network of Centres of Excellence), the Canada Research Chair in Aquatic Ecosystem Studies, and the Natural Sciences and Engineering Research Council of Canada (NSERC). Polar Shelf Canada provided logistical support for fieldwork (this is PCSP/ÉPCP publication number 059-08). Our ongoing field studies in the region are supported by Quttinirpaaq National Park and the Canadian Foundation for Innovation. Peer reviewed