RAINEY 9714276 ABSTRACT Hyper-arid deserts can be considered extreme environments with respect to their conditions of low humidity and low water activity. Such natural environments on Earth represent the conditions closest, with respect to the degree of desiccation, to those reported in free space or on the Martian surface. The Atacama Desert in Chile, with rainless regions and low humidity, is such a hyper-arid desert. Microbiological studies of arid environments have generally involved semi-arid to arid environments is available. The primary objective of the proposed study is to investigate enrichment and isolation methodologies that will maximize recovery of the entire range of prokaryotic diversity within a given sample from this extreme environment. This will be achieved by employing different isolation and enrichment techniques and monitoring the progress of these enrichments at the molecular level. Both aerobic and strictly anaerobic communities will be targeted. Various doses of ionizing and uv radiation will be applied as a selective enrichment strategy. This study will provide bacterial stains that will represent the diversity in a hyper-arid environment and that can be used for further studies on the survival of microorganisms in similar extreme environments, including extraterrestrial environments. These bacterial strains will constitute a resource of model microorganisms for future studies of the link between ionizing radiation resistance and desiccation resistance.
