1.   Invitro, sulphate reducing bacteria compete with methanogenic bacteria for hydrogen when sulphate is present.

2.   Breath methane was measured and viable counts and metabolic activities of methanogenic bacteria and sulphate reducing bacteria determined in faeces.

3.   Dietary sulphate may allow growth of sulphate reducing bacteria which inhibit the growth of methanogenic bacteria.

4.   Changes in dietary sulphate could alter the activity of sulphate reducing bacteria and thus affect methanogenesis in the colon.

5.   Breath methane was monitored and metabolic activities of methanogenic bacteria and sulphate reducing bacteria studied in faecal samples.

6.   Variations are expressed as sulphate reducing bacteria.