ABSTRACT
One century after their discovery by Beiyerink (1895), sulfate-reducing bacteria have become a very popular source of metalloproteins. This is because, as anaerobes, they needed to evolve several elaborated systems in order to conserve energy. Indeed, beside their capability to reduce sulfate and other sulfur compounds they can also utilize nitrate, fumarate, and, most extraordinarily, even oxygen as terminal electron acceptors. They can also reduce protons — atomic mass 1 — and about everything which is reducible, including uranium — atomic mass 238 — (Lovley et al., 1993) that is to say from the lightest to one of the heaviest elements on earth. As a result of their versatile metabolism, they contain a wealth of metalloproteins, some of them remarkably stable, which have provided much useful information to inorganic chemists and, recently, have allowed to uncover structures which are relevant to the comprehension of the mechanism of action of related proteins found in higher organisms.
