Oxalate Degradation by Gastrointestinal Bacteria from Humans

Abstract

Anaerobic bacteria that metabolize oxalic acid have only recently been isolated from the rumen and from other gastrointestinal habitats. They constitute a new genus and species, Oxalobacter formigenes. This report presents the first comparison of cultural counts of these organisms from human feces and indicates that numbers as high as 107/g may be present in feces from normal humans. Rates of oxalate degradation by mixed bacterial populations in feces from seven normal humans ranged from 0.1 to 4.8 µmol/(g · h). With fecal samples from eight patients that had undergone jejunoileal bypass surgery, rates were much lower [0–0.006 µmol/(g · h)]. We propose that oxalic acid degradation by Oxalobacter formigenes may influence absorption of oxalate from the intestine and that lower rates or lack of oxalate degradation in the colons of jejunoileal bypass patients may contribute to the increased absorption of dietary oxalate and the hyperoxaluria commonly associated with such patients.