The Inter-Valley Soil Comparative Survey: the ecology of Dry Valley edaphic microbial communities

Abstract

Recent applications of molecular genetics to edaphic microbial communities of the McMurdo Dry Valleys and elsewhere have rejected a long-held belief that Antarctic soils contain extremely limited microbial diversity. The Inter-Valley Soil Comparative Survey aims to elucidate the factors shaping these unique microbial communities and their biogeography by integrating molecular genetic approaches with biogeochemical analyses. Although the microbial communities of Dry Valley soils may be complex, there is little doubt that the ecosystem's food web is relatively simple, and evidence suggests that physicochemical conditions may have the dominant role in shaping microbial communities. To examine this hypothesis, bacterial communities from representative soil samples collected in four geographically disparate Dry Valleys were analyzed using molecular genetic tools, including pyrosequencing of 16S rRNA gene PCR amplicons. Results show that the four communities are structurally and phylogenetically distinct, and possess significantly different levels of diversity. Strikingly, only 2 of 214 phylotypes were found in all four valleys, challenging a widespread assumption that the microbiota of the Dry Valleys is composed of a few cosmopolitan species. Analysis of soil geochemical properties indicated that salt content, alongside altitude and Cu2+, was significantly correlated with differences in microbial communities. Our results indicate that the microbial ecology of Dry Valley soils is highly localized and that physicochemical factors potentially have major roles in shaping the microbiology of ice-free areas of Antarctica. These findings hint at links between Dry Valley glacial geomorphology and microbial ecology, and raise previously unrecognized issues related to environmental management of this unique ecosystem.

Insight into heavy metal resistome of soil psychrotolerant bacteria originating from King George Island (Antarctica)

“…Using publicly available data (Curtosi et al 2010;Guerra et al 2011;Lee et al 2012;Laluraj et al 2014;Vodopivez et al 2014;Grotti et al 2015;Kim et al 2015), we compared the concentrations of eight heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, and Zn) in 15 samples originating from different Antarctic regions (including five soil samples, eight marine/surface sediments samples and two snow/ice samples). Seven samples originated from King George Island.…”

Ecology and biogeochemistry of cyanobacteria in soils, permafrost, aquatic and cryptic polar habitats

“…These ice-free areas include mountain ranges, nunatuks and coastal deserts, some of which are bare depauperate arid soils. These regions offer a wide array of chemistries (Lee et al 2012) and soil types (Bockheim and McLeod 2008), and can be readily distinguished on the basis of morphological properties, particularly the amount and distribution of soluble salts and the degree of chemical weathering. For instance, the dominant soil types in the McMurdo Dry Valleys (MDV) include Typic Anhyorthels, Typic Haploturbels and Typic Anhyturbels, while the dominant soils on the Antarctic Peninsula are of ornithogenic origin (Ugolini and Bockheim 2008), although vegetation present in this region allows for more developed soils (Otero et al 2013).…”

“…Both classical and modern microbiological techniques have highlighted the presence of cyanobacteria in a wide range of terrestrial Arctic and Antarctic niches, including permafrost (Jansson and Tas¸ 2014), ice shelves Bottos et al 2008), rocks (Chan et al 2012;de los Rios et al 2014;Makhalanyane et al 2014), ponds and lakes (Taton et al 2003b;Bonilla et al 2005), glaciers and the resulting meltwater streams (Nadeau and Castenholz 2000;Jungblut et al 2005), and mineral soils (Wood et al 2008b; Lee et al 2012;Makhalanyane et al 2013a). Cyanobacteria are thought to be the primary colonizers in these niches (Vincent 2000), and are known to contribute to structural stability, moisture retention and fertility (Belnap and Gardner 1993).…”

Functional ecology of an Antarctic Dry Valley

“…Extensive recent research has focused on elucidating the biodiversity of Dry Valleys landscapes (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Classical microbiological studies identified edaphic Antarctic taxa by morphology and revealed a general recalcitrance to cultivation (17,18).…”