STUDY OF CONSTANCY OF HYDROGEN-CONSUMING FLORA OF HUMAN COLON

The constancy of the hydrogen consuming flora of the human colon was s tudied in 15 healthy subjects Wa two measurements obtained 18 to 36 mo nths apart. Hydrogen-disappearance rate and the major products of H-2- consuming bacteria, methane and sulfide, were measured during incubati on of fecal homogenates with excess hydrogen and sulfate. In 11/15, th e hydrogen consumption rate and the predominant hydrogen-consuming pat hway (methanogenesis, sulfate reduction, or neither) remained constant . However, major shifts in these pathways were observed in four subjec ts, with two losing and two gaming the ability to produce methane. Met hanogenesis was associated with the highest hydrogen consumption rate. This study demonstrates that clinically unrecognizable, major alterat ions of the colonic flora occur in healthy subjects. Understanding of the factors responsible for these alterations might allow for therapeu tic manipulation of the colonic flora.