Highly specialized microbial diversity in hyper-arid polar desert

Abstract

The McMurdo Dry Valleys in Antarctica are a cold hyperarid polar desert that present extreme challenges to life. Here, we report a culture-independent survey of multidomain microbial biodiversity in McKelvey Valley, a pristine example of the coldest desert on Earth. We demonstrate that life has adapted to form highly-specialized communities in distinct lithic niches occurring concomitantly within this terrain. Endoliths and chasmoliths in sandstone displayed greatest diversity, whereas soil was relatively depauperate and lacked a significant photoautotrophic component, apart from isolated islands of hypolithic cyanobacterial colonization on quartz rocks in soil contact. Communities supported previously unreported polar bacteria and fungi, but archaea were absent from all niches. Lithic community structure did not vary significantly on a landscape scale and stochastic moisture input due to snowmelt resulted in increases in colonization frequency without significantly affecting diversity. The findings show that biodiversity near the cold-arid limit for life is more complex than previously appreciated, but communities lack variability probably due to the high selective pressures of this extreme environment.

Possible interactions between bacterial diversity, microbial activity and supraglacial hydrology of cryoconite holes in Svalbard

“…Morphological examination of phototrophic microbes has been useful in comparison of Arctic and Antarctic cryoconite holes (Porazinska et al, 2004;Stibal et al, 2006), but the limited range of observable morphology hinders the application of this approach to most non-photosynthetic bacteria. Although archaea have been reported from several peri-glacial habitats (Sjöling and Cowan, 2003;Nicol et al, 2006), other PCR-based investigations have also failed to detect their presence (Pointing et al, 2009); (Supplementary Data S1). Further study using PCR-independent approaches (for example, phospholipid ether lipid analysis; Gattinger et al, 2003) could usefully be applied to provide a definitive determination of the occurrence of archaea within cryoconites.…”

Microbiology of Eutrophic (Ornithogenic and Hydrocarbon-Contaminated) Soil

“…Lithic communities in McKelvey Valley (Pointing et al 2009) and the Miers, Marshall, and Garwood Valleys (Khan et al 2011) were found to be distinct from surrounding soil communities, suggesting substantial dissemination of biomass to the local environment is restricted. Similarly, while the presence of an animal carcass at a site may drastically alter the physicochemical parameters and bacterial community composition of the soil, the effects have been found to be restricted to the immediate vicinity of the augmentation (Tiao et al 2012).…”

Rapid microbial response to the presence of an ancient relic in the Antarctic Dry Valleys

“…Devoid of vascular plant life [8][9][10] , the Dry Valley ecosystem supports only a handful of microscopic invertebrate, lichen and moss species 9,10 . However, the bulk of Dry Valley biodiversity and biomass consists of edaphic bacteria 8,11,12 , as few other organisms can endure the region's extreme temperature and light regimes, high soil salt concentrations, near-negligible levels of organic C and N, and scarcity of liquid water 10,12 . It has been suggested that these soil microbial communities are principally sustained and structured by the location and distribution of legacy C sources in the form of ancient lake sediments [13][14][15][16] .…”