Viability, diversity and composition of the bacterial community in a high Arctic permafrost soil from Spitsbergen, Northern Norway

Abstract

The viable and non-viable fractions of the bacterial community in a 2347-year-old permafrost soil from Spitsbergen were subjected to a comprehensive investigation using culture-independent and culture-dependent methods. LIVE/DEAD BacLight staining revealed that 26% of the total number of bacterial cells were viable. Quantitatively, aerobic microcolonies, aerobic colony-forming units and culturable anaerobic bacteria comprised a minor fraction of the total number of viable bacteria, which underlines the necessity for alternative cultivation approaches in bacterial cryobiology. Sulfate reduction was detected at temperatures between -2 degrees C and 29 degrees C while methanogenesis was not detected. Bacterial diversity was high with 162 operational taxonomic units observed from 800 16S rDNA clone sequences. The 158 pure cultures isolated from the permafrost soil affiliated with 29 different bacterial genera, the majority of which have not previously been isolated from permafrost habitats. Most of the strains isolated were affiliated to the genera Cellulomonas and Arthrobacter and several of the pure cultures were closely related to bacteria reported from other cryohabitats. Characterization of viable bacterial communities in permafrost soils is important as it will enable identification of functionally important groups together with the as yet undescribed adaptations that bacteria have evolved for surviving subzero temperatures for millennia.

Culturable bacteria community development in postglacial soils of Ecology Glacier, King George Island, Antarctica

“…It is more likely that the isolates cultivated here were of subglacial origin, as no representatives of the genus were found in surface ice or anywhere else along the transect. For example, recently described Leifsonia species were isolated from cold habitats such as soil near a Himalayan Glacier, Southern Ocean sediment (Pindi et al 2009), Antarctic pond cyanobacterial mat (Reddy et al 2003), and Spitsbergen permafrost (Hansen et al 2007), suggesting this genus is well adapted to life in polar and alpine ecosystems. One of its ecological functions could be supplying autotrophs with phosphorus and metal ions of biological importance such as Fe, Mn, Ca, K, and Mg by weathering of poorly available sources (insoluble mineral deposits).…”

“…In this respect, the bioleaching properties of Leifsonia spp. have been widely recognized (Hansen et al 2007;Delvasto et al 2008;Frey et al 2010).…”

“…Pedobacter spp. have been isolated from soils, permafrost, glacial, and near glacial environments and from decaying lichens (Bai et al 2006;Männisto and Häggblom 2006;Hansen et al 2007;Yoon et al 2007;Simon et al 2009). Members of the Sphingobacteriaceae such as Pedobacter sp.…”

Permafrost Meta-Omics and Climate Change

“…However, these studies do not reveal which genes are actively expressed and thus which potential biochemical functions are being realized at a given time. In permafrost, this distinction between metabolic potential (as indicated by genomes) and metabolic activity may be especially important because constant subzero temperatures create excellent preservation conditions and inactive or dead cells (along with their genomes) may remain in the soil for extended periods of time (Dmitriev et al 2001, Hansen et al 2007. To better determine which parts of a community's overall functional potential are actually being realized by microbial metabolic activity, metagenomic data can be complemented with other approaches that provide information about gene expression.…”

“…The potential for sulfur metabolism is clearly present in permafrost microbes. A sulfur-reducing bacterium was isolated from ancient permafrost (Vatsurina et al 2008), and 16S rRNA gene sequences from sulfate-reducing and sulfur-oxidizing bacteria were found in permafrost (Hansen et al 2007, Steven et al 2007). Taxonomic assignment of metagenomic sequences to sulfate reducers and the presence of genes involved in sulfate reduction also revealed that microbes that use sulfate as a TEA are present in permafrost (Chauhan et al 2014, Lipson et al 2013.…”