Effects of water regime on archaeal community composition in Arctic soils

Summary Effects of water regime on archaeal communities in Arctic soils from Spitsbergen were studied using denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA genes, with subsequent sequenc- ing of amplicons and ordination analysis of binary DGGE data. Samples with major differences in soil water regime showed significant differences in their archaeal community profiles. Methanomicrobiales , Methanobacteriaceae and Methanosaeta were detect- able only in environments that were wet during most of the growth season, while a novel euryarchaeotal cluster was detected only in less reduced solifluction material. Group 1.3b of Crenarchaeota had a high rel- ative abundance within the archaeal community in a wide range of wet soils. Along a natural soil moisture gradient, changes in archaeal community composi- tion were observed only in upper soil layers. The results indicated that members of Methanomicrobi- ales were relatively tolerant to soil aeration. Differ- ences in archaeal community composition associated with soil water regime were predominant over regional and seasonal variation, and over differences between individual wetlands. The results suggest that the observed 'on-off switch' mechanism of soil hydrology for large-scale variations in methane emis- sions from northern wetlands is at least partly caused by differences in the community structure of organ- isms involved in methane production.