PSYCHROACTIVE METHANOGENIC ARCHAEA AS ANALOGUES TO HYPOTHETIC MICROORGANISMS INHABITING SUBSURFACE MARTIAL ECOSYSTEMS

摘要

Martial conditions include low temperature and an atmosphere that contains large amounts of carbon dioxide and only traces of oxygen. Subsurface life on Mars would need to use chemical energy through the oxidation of inorganic matter. Methanogens are chemolithoautotrophs that can only develop under anoxic conditions consuming hydrogen and CO_2 as the only source of energy and carbon. They produce methane, an important greenhouse gas and inhabit different terrestrial environments including extreme ecosystems. Assuming that hydrogen of geological origin and cold liquid water are present beneath the martial surface, low temperature methanogenic archaea are most substantial candidates among all known microorganisms for surviving under such conditions. Presently, little is know about psychrophilic archaea despite the fact of their important participation in terrestrial microbial cycles. Here, we report on seven new methanogens isolated from different cold environments and able to grow at temperature close to zero.