title: Metatranscriptomic analysis of arctic peat soil microbiota.
abstract: Recent advances in meta-omics and particularly metatranscriptomic approaches have enabled detailed studies of the structure and function of microbial communities in many ecosystems. Molecular analyses of peat soils, ecosystems important to the global carbon balance, are still challenging due to the presence of coextracted substances that inhibit enzymes used in downstream applications. We sampled layers at different depths from two high-Arctic peat soils in Svalbard for metatranscriptome preparation. Here we show that enzyme inhibition in the preparation of metatranscriptomic libraries can be circumvented by linear amplification of diluted template RNA. A comparative analysis of mRNA-enriched and nonenriched metatranscriptomes showed that mRNA enrichment resulted in a 2-fold increase in the relative abundance of mRNA but biased the relative distribution of mRNA. The relative abundance of transcripts for cellulose degradation decreased with depth, while the transcripts for hemicellulose debranching increased, indicating that the polysaccharide composition of the peat was different in the deeper and older layers. Taxonomic annotation revealed that Actinobacteria and Bacteroidetes were the dominating polysaccharide decomposers. The relative abundances of 16S rRNA and mRNA transcripts of methanogenic Archaea increased substantially with depth. Acetoclastic methanogenesis was the dominating pathway, followed by methanogenesis from formate. The relative abundances of 16S rRNA and mRNA assigned to the methanotrophic Methylococcaceae, primarily Methylobacter, increased with depth. In conclusion, linear amplification of total RNA and deep sequencing constituted the preferred method for metatranscriptomic preparation to enable high-resolution functional and taxonomic analyses of the active microbiota in Arctic peat soil.
authors.affiliation: Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Tveit
authors.affiliation: Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria Austrian Polar Research Institute, Vienna, Austria tim.urich@univie.ac.at mette.svenning@uit.no.
authors.forename: Tim
authors.initials: T
authors.lastname: Urich
authors.affiliation: Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway tim.urich@univie.ac.at mette.svenning@uit.no.
authors.forename: Mette M
authors.initials: MM
authors.lastname: Svenning
mesh_terms: D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D058448:Biota; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D053858:Metabolic Networks and Pathways / Q000235:genetics; D054892:Metagenome; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil; D012988:Soil Microbiology; D013538:Svalbard
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D011134:Polysaccharides; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S; D012987:Soil