Anaerobic Eury- and Crenarchaeota inhabit ectomycorrhizas of boreal forest Scots pine

Members of the euryarchaeotal genera Methanolobus and Halobacterium as well as group 1.1c Crenarchaeota were enriched from ectomycorrhizal samples and cultured under anaerobic conditions. 16S rRNA gene sequences of Methanolobus were obtained in a H₂ + CO₂ atmosphere and autofluorescent putatively methanogenic microbial cells were detected by epifluorescence microscopy of the anaerobic methane-producing enrichment cultures. Halobacterium and group 1.1c Crenarchaeota grew anaerobically when either H₂ or CH₄ was added to the atmosphere. Group 1.1c Crenarchaeota were also enriched under aerobic conditions on mineral media, but only when methane or methanol was added as carbon sources. The 16S rRNA gene sequences of 1.1c Crenarchaeota grown under both anaerobic and aerobic conditions were highly similar. Our study demonstrates the growth of group 1.1c Crenarchaeota and Halobacteria derived from non-extreme soil environment in non-saline enrichments under anaerobic conditions. The results suggest that 1.1c Crenarchaeota may play a role in the cycling of C-1 substrates in the boreal forest soil ecosystem.