"The High-Altitude Andean Lakes (HAAL) in the South American Puna-High Andes” are an almost unexplored ecosystem of shallow lakes at altitudes from 3,000 to 6,000 m above sea level. Although exposed to a broad range of extreme conditions they harbour an abundant microbial biodiversity that thrive in environmental conditions of high resemblance to those present in Earth`s early atmosphere. As part of our team in Argentina I have investigated this wide-ranging diversity by culturable and non-culturable methods: so far we have assembled a collection of 200 extremophilic strains from shallow waters, sediments, flamingo faeces and even stromatolites (the only modern stromatolite-ecosystem on Earth recorded at such hostile environments!).The HAAL are clearly conditioned by the high intensity of UV irradiation - in addition to further extreme conditions (e.g. hypersalinity, drastic temperature changes, desiccation, high pH). The rich microbial diversity found in these lakes points to the presence of outstandingly active DNA repair systems - topics of high interest for colleagues worldwide investigating biomass for energy research. Unfortunately our scientific methods are limited - and thus I would like to use the expertise and excellent equipment at the host institute to investigate extensively the strain resistance mechanisms towards UV. These studies on indigenous extremophiles will provide important information about early life – but clearly are of biotechnological and astrobiology interest too.The research will focus on screening and molecular analyses of blue-light driven enzymatic activities such as photolyases involved in DNA-repairing systems - and in particular from the HAAL stromatolite-ecosystems. Their further overexpression and functional study will lead to their photochemical characterization and will highlight the potential of these microbial communities as valuable sources of novel bacteria and bio-molecules of biotechnology interest."