Occurrence of sulphate reducing bacteria in the human intestinal flora and in the aquatic environment

The occurrence of sulphate reducing bacteria at high levels in various types of water suggests their faecal origin. This prompted an examination of faecal specimens for sulphate reducing bacteria. In a random choice of the same samples E. coli was also enumerated.Sulphate reducing bacteria were found at a mean rate of 10⁶/100 g in faeces, 10⁶/100 ml in crude sewage, 10⁵/100 ml in river water and about 10²/100 ml in drinking water. Distribution curves of sulphate reducing bacteria and E. coli were found to be rather similar in some types of water. The ubiquitous character of sulphate reducing bacteria, their high resistance to extraenteric conditions and the rather complicated techniques required for their detection make them nevertheless less appropriate as indicator organisms in practical monitoring work.