INTRODUCTION

Early in 1886, it was demonstrated that the addition of gypsum (CaSO4ċ2H2O) to anaerobic mud enrichments containing cellulose led to the production of the malodorous gas, hydrogen sulphide (Hoppe-Seyler, 1886). Soon after, Beijerinck first provided evidence of a microorganism reducing sulphate into sulphide, named as Spirillum desulphuricans (Beijerinck, 1895), which was the first sulphate-reducing bacterium (SRB) isolated in the world. As pointed out by Voordouw (1995), Beijerinck had already addressed, at the end of the nineteenth century, questions to the scientific community with regard to the metabolism and ecological distribution of the SRB, which are still nowadays themes of debate. SRB were first believed to use a limited range of substrates as energy sources (e.g. hydrogen, lactate, ethanol, etc. …), but recent biochemical and microbiological studies have greatly extended the range of electron donors and electron acceptors known to be used by SRB (Fauque et al., 1991; Widdel, 1988). Indeed the latter may have an autotrophic, lithoautotrophic, heterotrophic, or respiration type of life under anaerobiosis and their possible microaerophilic nature has been discussed in the literature (Fauque and Ollivier, 2004). Besides their common ability to use sulphate as terminal electron acceptor, many of them were shown to utilize other mineral sulphur compounds, including elemental sulphur, thiosulphate, sulphite, polythionates and polysulphide (Le Faou et al., 1990). In addition, SRB have been demonstrated to reduce a wide range of heavy metals and radionuclides including Fe(III), and U(VI).