Molecular assessment of microbial communities in a northern Wisconsin peatland

The diversity of bacteria, in different terrestrial topographical sites and habitats (in Sphagnum tissues and peat), in a northern Wisconsin peatland was characterized over the snowfree seasons. Environmental parameters including pH, methane production and emission, and dissolved oxygen were also measured in an attempt to correlate them to microbial diversity. As the only organisms known to be capable of destroying methane, methane-oxidizing bacteria (MOB) serve the important function of removing methane generated in the anaerobic strata of peatlands before its emission into the atmosphere. In this study, using PCR primers specific for type II MOB in PCR-ARISA (automated rRNA intergenic spacer analysis) we provide the first evidence that a putative MOB may be associated with living Sphagnum as well as dead Sphagnum-dominated peat. We speculate that in methane-rich environments such as peatlands, MOB may occupy Sphagnum hyaline cells, an environment rich in essential oxygen emitted from surrounding green cells. We also discovered eight partial 16S rRNA gene sequences using the same PCR primers, all representing novel taxa and forming a distinct phylogenetic cluster. These clones are phylogenetically most closely related to Azospirillum/Magnetospirillum/ Phaeospirillum and only distantly related to known type II MOB. Multivariate analyses did not detect any correlation in the microbial community detected by these primers in regard to differences in topography, habitat (in Sphagnum moss or in peat) and over the seasons. We also employed PCR-ARISA to characterize the (Domain) Bacterial communities in the same habitats and sites, and over the same sampling period. A total of 334 ARISA peak types, representing distinct genotypes, were detected. Multivariate analysis found correlations between the Bacterial community and habitat (Sphagnum vs. peat), but not between sites (hummocks vs. hollows).