Bacterial composition of soils of the Lake Wellman area, Darwin Mountains, Antarctica

Abstract

The aim of this study was to examine the bacterial composition of high latitude soils from the Darwin-Hatherton glacier region of Antarctica. Four soil pits on each of four glacial drift sheets were sampled for chemical and microbial analyses. The four drifts-Hatherton, Britannia, Danum, and Isca-ranged, respectively, from early Holocene (10 ky) to mid-Quaternary (ca 900 ky). Numbers of culturable bacteria were low, with highest levels detected in soils from the younger Hatherton drift. DNA was extracted and 16S rRNA gene clone libraries prepared from samples below the desert pavement for each of the four drift sheets. Between 31 and 262 clones were analysed from each of the Hatherton, Britannia, and Danum drifts. Bacterial sequences were dominated by members of the phyla Deinococcus-Thermus, Actinobacteria, and Bacteroidetes. Culturable bacteria, including some that clustered with soil clones (e.g., members of the genera Arthrobacter, Adhaeribacter, and Pontibacter), belonged to Actinobacteria and Bacteroidetes. The isolated bacteria are ideal model organisms for genomic and phenotypic investigations of those attributes that allow bacteria to survive and/or grow in Antarctic soils because they have close relatives that are not tolerant of these conditions.

Isolation of Uncultured Bacteria from Antarctica Using Long Incubation Periods and Low Nutritional Media

“…Sequences of organisms belonging to class Thermoleophilia have been constantly reported in samples from Antarctica (Chong et al, 2012; Aislabie et al, 2013; Kumar et al, 2013; Rampelotto et al, 2015; Ji et al, 2016; Pudasaini et al, 2017), reaching relative abundances of 15% in some samples (Ji et al, 2016). Although highly present, no isolate of this class has been reported from this type of environment to date, making this the first report of Thermoleophilia isolation from an Antarctic sample in addition to the novelty of this species.…”

Microbiology of Eutrophic (Ornithogenic and Hydrocarbon-Contaminated) Soil

“…Bacterial community structures were found to be influenced by soil development, soil water content, organic carbon content, and pH (Aislabie et al 2012), and soil diversity was found to be highest in the least developed soil (Aislabie et al 2013). Soils were dominated by bacteria grouping to the phyla Deinococcus-Thermus, Actinobacteria, and Bacteroidetes (Aislabie et al 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).…”

“…Recently, cultivation-independent analyses of the bacterial communities in soils of the Darwin Mountains have shown bacterial abundance and composition to be influenced most strongly by soil age and physicochemical properties (Aislabie et al 2012(Aislabie et al , 2013Magalhães et al 2012). Bacterial community fingerprinting analyses of soils in the Darwin Mountains revealed bacterial diversity was greatest in younger, less developed soils, which had lower salinity and higher C/N ratios than older soils (Magalhães et al 2012).…”

Diversity of extremophilic bacteria in the sediment of high-altitude lakes located in the mountain desert of Ojos del Salado volcano, Dry-Andes

“…These lakes might be inhabited by several hitherto unknown microorganisms with special adaptive strategies to the extreme environmental conditions (Ordoñez et al 2009). Former studies focused mainly on other lakes of the Dry-Andes (Demergasso et al 2008;Dorador et al 2008Dorador et al , 2013Cabrol et al 2009;Farías et al 2009Farías et al , 2014Lynch et al 2012;Scott et al 2015), and research was also performed on similar environments, for example Antarctic lakes and permafrost (Goordial et al 2016;Aislabie et al 2013;Antibus et al 2012;Cowan et al 2002) and high-altitude lakes or permafrost of the Tibetan Plateau (Wu et al 2006;Xing et al 2009;Zhang et al 2007). Understanding the microbial processes in degrading permafrost is also an important issue, since thawing is proven to cause shifts in microbial communities, functional gene abundances which might be responsible for changes in global carbon cycle (Mackelprang et al 2011;Tas et al 2014;Hultman et al 2015).…”