GENE FUNCTION ANALYSIS IN EXTREMOPHILES: THE nif REGULON OF THE STRICT IRON OXIDIZING BACTERIUM Leptospirillumferrooxidans

摘要

In Centro de Astrobiologia it has been considered the Tinto river (1, 2, 5) as a model ecosystem to study life based on iron. The final goal is to study the biological and metabolic diversity in microorganisms living there, following a genomic approach, to get insights to the mechanisms of adaptation to this environment. The Gram-negative bacterium Leptospirillumferrooxidans is one of the most abundant microorganisms in the river (2), and it is one of the main responsible in maintenance of pH balance and, as a consequence, the physico-chemical properties of the ecosystem. We have constructed a Shotgun DNA microarrays from this bacterium and we have used it to studied its genetic capacity for nitrogen fixation. With mis approach we have identified most of the genes necessary for dinitrogen (N2) reduction, confirming the capacity of L. ferrooxidans as a free diazotrophic (nitrogen fixer) microorganism.