Establishment of microbial assemblages in polar regions subject to significant effects of climate change, their participation in the biogeochemical cycling of carbon, nitrogen and phosphorus

Dr. Silvia Batista, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE)

King George Island (Sea Antarctica) is the largest in the South Shetland archipelago. The Fildes Peninsula, located southwest of this island, is the region with no more permanent permanent ice cover, with eroded soils derived mainly from volcanic and sedimentary rocks. During the summer season, the landscape takes on a particular aspect that contrasts with the adjacent areas covered by the Bellinghausen Glacier. The rocky landscape with some lakes is covered by small thawing glaciers that form with water from the glacier and molten snow. As the summer progresses, carpets of bryophytes, lichens and microbial mats are established, creating a landscape with a matted appearance. Microbial mats are benthic communities that exist associated with these bodies of water and de-icing systems.

This island concentrates the most scientific bases, with the inevitable human influence associated. It should be noted that the activities carried out in Antarctica are governed by the Protocol to the Antarctic Treaty on Environmental Protection signed in Madrid in 1991. It establishes clear rules governing human activity in this continent, trying to minimize The human impact on native flora and fauna for the preservation of the Antarctic ecosystem.

Our work is developed in collaboration with researchers from UNAM (Mexico). One of the areas of study is oriented to characterize the microorganisms of the Antarctic environment and in particular the genetic elements that can be transferred laterally between them. Some elements have genes that when expressed contribute to the organism optimize its adaptation to the environment. On the other hand, the composition of some of these modules is considered as an indicator of human influence. Our study is oriented to identify and estimate the abundance of the same, in order to correlate them with the human and animal presence in the island. In this sense, we have isolated bacteria from different sites of the peninsula, carrying fragments of DNA that code for resistance to several antibiotics, almost identical to that present in some clinical isolates.

The second line of study is related to climate change. The highest rates of global warming have been observed in this Antarctic region. In the Fildes Peninsula, the Bellinghausen glacier has steadily receded in the last five decades. As glaciers recede, substrate is exposed that is rapidly colonized by native and exotic organisms. This line of work studies the microbial composition of carpets and their capacity to metabolize nitrogen, as a potentially limiting element for the development of the microbial community. The proposal includes the study of changes in the composition and physiology of these communities before climate change scenarios. So far, studies show that these communities have a very diverse composition and have the capacity to reduce atmospheric nitrogen (biological nitrogen fixation) and to oxidize the nitrate through a process called denitrification, thus completing the cycle of this element.