Bacterial succession in Antarctic soils of two glacier forefields on Larsemann Hills, East Antarctica

Abstract

Antarctic glacier forefields are extreme environments and pioneer sites for ecological succession. Increasing temperatures due to global warming lead to enhanced deglaciation processes in cold-affected habitats, and new terrain is becoming exposed to soil formation and microbial colonization. However, only little is known about the impact of environmental changes on microbial communities and how they develop in connection to shifting habitat characteristics. In this study, using a combination of molecular and geochemical analysis, we determine the structure and development of bacterial communities depending on soil parameters in two different glacier forefields on Larsemann Hills, East Antarctica. Our results demonstrate that deglaciation-dependent habitat formation, resulting in a gradient in soil moisture, pH and conductivity, leads to an orderly bacterial succession for some groups, for example Cyanobacteria, Bacteroidetes and Deltaproteobacteria in a transect representing 'classical' glacier forefields. A variable bacterial distribution and different composed communities were revealed according to soil heterogeneity in a slightly 'matured' glacier forefield transect, where Gemmatimonadetes, Flavobacteria, Gamma- and Deltaproteobacteria occur depending on water availability and soil depth. Actinobacteria are dominant in both sites with dominance connected to certain trace elements in the glacier forefields.

Microbiology of Eutrophic (Ornithogenic and Hydrocarbon-Contaminated) Soil

“…Cyanobacteria, Deltaproteobacteria, and Gemmatimonadetes were positively associated with soil moisture and pH, while magnesium, calcium, and potassium were found to influence distributions of Actinobacteria (Bajerski and Wagner 2013). Bacteroidetes were found to be the most abundant in the vicinity of glaciers, which the authors suggest may be related to low temperature and high water availability at these locations (Bajerski and Wagner 2013). This work provides insight into the process of bacterial succession following glacial retreat and establishes relationships between bacterial community structure and physicochemical properties of soils in the region.…”

“…The study revealed the dominance of Actinobacteria, Acidobacteria, Proteobacteria, Bacteroidetes, Cyanobacteria, and Chloroflexi and several trends in phyla level distributions within the glacial forefield sites (Bajerski and Wagner 2013). Cyanobacteria, Deltaproteobacteria, and Gemmatimonadetes were positively associated with soil moisture and pH, while magnesium, calcium, and potassium were found to influence distributions of Actinobacteria (Bajerski and Wagner 2013). Bacteroidetes were found to be the most abundant in the vicinity of glaciers, which the authors suggest may be related to low temperature and high water availability at these locations (Bajerski and Wagner 2013).…”

“…Bacteroidetes, Firmicutes, Cyanobacteria, and Alphaproteobacteria were found to be more abundant relative to other taxa in soils of Fossil Bluff (71°19 0 S) and Coal Nunatak (72°03 0 ) on Alexander Island than at sites on the Falkland Islands, Signy Island, and Anchorage Island (51°76 0 S-67°34 0 S) (Yergeau et al 2009). Several phyla were significantly influenced by soil physicochemical factors, as the proportion of Chloroflexi and Betaproteobacteria were negatively (Yergeau et al 2007b); West Antarctic soil sequences (180) are from a study in the Ellsworth Mountains (Yergeau et al 2007b); Victoria Land soil sequences, a total of 426 clone sequences and 25976 pyrosequencing reads, were included from the McMurdo Dry Valleys, from studies in the Miers Valley Tiao et al 2012), Beacon Valley, Wright Valley, Battleship Promontory , Luther Vale (Niederberger et al 2008), and Bull Pass and Vanda in the Wright Valley ); ornithogenic soil sequences (514) are from Cape Hallett and Cape Bird in the Ross Sea region (Aislabie et al 2009); East Antarctic soil sequences (1396) were included from the Larsmann Hills (Bajerski and Wagner 2013) and Schirmacher Oasis (Shivaji et al 2004); and the Transantarctic Mountain soil sequences (361) were from the Darwin Mountains (Aislabie et al 2013). The trees were constructed using ARB (Ludwig et al 2004), with DNADIST and Neighbor joining analysis, and the percentage of sequences in each phyla is shown (in brackets).…”

“…An analysis of bacterial communities associated with glacier forefields in the Larsemann Hills has been completed using a suite of culture-dependent and molecular techniques (Bajerski and Wagner 2013). The study revealed the dominance of Actinobacteria, Acidobacteria, Proteobacteria, Bacteroidetes, Cyanobacteria, and Chloroflexi and several trends in phyla level distributions within the glacial forefield sites (Bajerski and Wagner 2013).…”

Potential sources of microbial colonizers in an initial soil ecosystem after retreat of an alpine glacier

“…Most alpine glaciers are currently retreating leading to formation of new terrestrial ecosystems. Glacier ecosystems have been used extensively to investigate dynamics of soil formation in relation to shifts in microbial communities (for example, Bernasconi et al, 2011;Zumsteg et al, 2012;Bajerski and Wagner, 2013;Rime et al, 2015). They also represent ideal ecosystems to study natural establishment of microbial communities in terrestrial environments (Edwards et al, 2014).…”