Degradation of pectic substances by two pectate lyases from a human intestinal bacterium, Clostridium butyricum-beijerinckii group

Clostridium butyricum-beijerinckii group, an anaerobic human intestinal bac terium, produced exo-pectate lyase, endo-pectate lyase, and pectin methyles terase, but not polygalacturonase. The production of the two pectate lyases was strongly influenced by the composition of the carbon sources added to the medium. The enzymes secreted by the bacterium into the human large inte stine cooperatively digested pectic substances, producing mainly 4,5-unsatu rated digalacturonic acid with the participation of the pectin methylestera se. The findings suggest that in the human intestine the bacterium contribu tes to the digestion of ingested pectic substances.