ABSTRACT
Sulphur is a Group VI element which shows the expected valency of-2 in simple molecules such as H2S, thiols (RSH) and thioethers (RSR) (where R is an alkyl group). Thiol and thioether groups may be present also in complex molecules, and as such represent potential sites for microbial metabolism. Sulphur also shows additional valencies, e.g. 4 and 6, usually by forming dative bonds with other elements especially oxygen (Figure 12.1) (Damani, 1989). The presence of oxygen on the sulphur influences its polarity and its potential for metabolism by the intestinal flora. Because of the diversity of sulphur-containing compounds, the scope of this chapter is potentially very large and therefore it will concentrate on the role of the gut bacteria in the metabolism of foreign compounds in humans.
