Microbiology in Antarctic Deserts

Antarctica is one of the most extreme terrestrial environments both at the physical and chemical levels. However, their soils have a great diversity, some richer in nutrients, usually located at coastal regions, and others more oligotrophic (poor in nutrients) located in the so-called polar deserts (e.g. Dry Valleys). Due to the extreme conditions of these deserts (low water availability, oligotrophy, higher UV radiation incidence) it was believed that these regions were inhospitable, a description done by Captain Robert Scott in 1903 that persisted to the 70’s. With advances in molecular biology it became possible to detect the presence of microorganisms in these habitats, checking also if the organisms were broadly distributed in the soils (even in the ones that didn’t appear to have available water or organic matter). The structure of these communities is simple, composed only by a few trophic levels (primary producers as cyanobacteria and decomposers as some bacteria and fungi), even though they can be highly diverse. Regarding the nature of this diversity, many questions still remain unanswered. It is believed that the diversity may have grown in situ, however some studies suggest that some organisms may have arrived from distant places attached to particles moved by the wind.

Different types of lytic environments (refugees)

And how can these communities have survived in these extreme conditions?

Besides their biological adaptations, communities can develop in more protected areas, like lytic environments: cracks and rock interstices or even mummified seals carcasses (that allow physical stability, higher protection against UV rays and increase the water availability). This way, these environments became “hot spots” of biodiversity contributing to the increase of productivity.

What are the effects of climate change on microbial communities of Antarctic dry deserts?

Although unpredictable, it it believed that global warming can induce the growth of other microbial groups, changing this way the competition inside the community, and contributing to a biodiversity change which, in turn, will result in a change in the microbial activity and the biogeochemical cycles (regulated by biological activity). This is relevant because pre-established interactions between species can act like caps to responses to ecosystems changes; however changes in these interactions can put in risk their integrity.

Biodiversity control at Antarctic extreme environment

Source:

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Cary, S. C., McDonald, I. R., Barrett, J. E., & Cowan, D. A. (2010). On the rocks: the microbiology of Antarctic Dry Valley soils. Nature Reviews Microbiology, 8(2), 129-138.  doi: 10.1038/nrmicro2281

Author: Maria Monteiro

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