“…Sulphatereducing bacteria are environmentally important micro-organisms. Their influences can be divided into ecological and economic effects (Postgate 1982). Probably the most significant aspect of their metabolism is the production of H,S, which, being a very strong reducing agent, is able to inhibit the growth of certain aerobic micro-organisms, Conversely, H,S plays an important role in the natural environment in that it functions as an electron donor for the growth of some sulphur bacteria.…”