Plasmids of bacteria and archaeas isolated from living stromatolites from the Argentinean Puna

DIB, JULIÁN RAFAEL

Kiel

Encuentro; Network Meeting of the Alexander von Humboldt Foundation; 2012

Fundación Alexander von Humboldt

Stromatolites are considered as some of the most ancient records of life on Earth. They occur widely in the fossil record of the Precambrian, but are rare today. Living or ‘modern’ stromatolites are mostly found in hypersaline lakes and marine lagoons with extreme conditions. These areas are of particular scientific interest since their study can give us clues to understand the origin of life on Earth and to comprehend the geochemical cycles of the elements that constitute these rocks. One of the most recently found living stromatolites were discovered by our lab in February 2009, in Laguna Socompa and Tolar Grande, in Salta province, Argentina (www.nature.com/news/2009/090917/full/news.2009.924.html) (Figure 1). These stromatolites are unique compared to others as they are located at above 4,000 m in a pristine and extreme environment where they are exposed to high UV radiation, low O2 content, wide fluctuations in daily temperatures, hypersalinity, low level of nutrient availability, and high concentrations of heavy metals, especially arsenic. These conditions are similar to the ones of the beginning of life on earth. We established a collection of extremophile bacteria and archaeas isolated from stromatolites and high-altitude lakes from the argentinean Puna. Bacteria from these environments need to develop efficient mechanisms and strategies to overcome above described severe conditions. High UV, for instance, is considered one of the most extreme conditions that microorganisms living in these environments have to suffer. The aim of this project is the screening, isolation, and characterization, including DNA sequencing and bioinformatic analyses, of large plasmids in actinobacteria, other bacteria and archaeas previously isolated from living stromatolites from high-altitude Andean lakes. Our major attempt is to identify genetic determinants provided by such plasmids, that might be essential for survival in these oligotrophic, pristine, and extreme environments.