In Picrophilus torridus, a euryarchaeon that grows optimally at 60 C and pH and thus represents the most acidophilic thermophile known, glu-cose oxidation is the first proposed step of glucose catabolism via a non-phosphorylated variant of the Entner–Doudoroff pathway, as deduced from the recently completed genome sequence of this organism. The P. torridusgene for a glucose dehydrogenase was cloned and expressed in Escherichia coli, and the recombinant enzyme, GdhA, was purified and characterized
