Astrobiological Significance of Sulphur-reducing Microorganisms

Since 1937 we know the existence of microorganisms able to reduce elemental sulphur. This ability is shared among Bacteria and Archaea members, some are mesophilic or moderately thermophilic, but also extremely thermophilic are described. Metabolic capabilities of sulphur-reducing microorganisms are various, being able to produce organic matter, as lithotrophs, as well as to produce organic matter destruction, as organotrophs. Thermotoga (Bacteria)orThermococcales and Thermoproteales (Archaea), extremely thermophilic, strictly anaerobic, life forms able to growth between + 80–120 °C, are important subjects for astrobiological studies.They may providegood analogs for microbial life forms that may exists outside the planet Earth, particularly thinking to Jupiter’s moon Io, where intense volcanic activity, sulphur and sulphur compounds have been described.