Measurement of mercaptoacetate levels in anaerobic batch culture of colonic bacteria

Abstract Mercaptoacetate levels were measured by HPLC utilizing precolumn derivitisation with o -phthalaldehyde in bacteria suspensions incubated anaerobically in batch culture. Reproducibility of measurement had a coefficient of variation of 4.8% and the recovery was 98%. Suspensions of faecal bacteria were incubated under H₂/CO₂ or N₂/CO₂ (4:1 v/v) in anaerobic dilution solution, reduced with ascorbate, with either glucose, starch, dextran or dextran sulphate. Production of the short chain fatty acids (acetate, propionate and butyrate) and utilization of H₂ showed continuing microbial fermentation. Under these conditions mercaptoacetate was produced at variable rates between 0.06–12.34 μmol/g (dry weight) over 24 h. Incubations from 24 to 48 h revealed that mercaptoacetate was both produced and utilized. Endogenous mercaptoacetate production in the colon would assist in maintaining anaerobiosis in an environment exposed to variable amounts of oxygen.