Properties of lactase produced by enteropathogenic Escherichia coli from diarrhoeic children

Abstract

The quantity of lactase produced by enteropathogenic Escherichia coli (EPEC) was significantly higher (P< 0.01) than that produced by non-EPEC. The enzyme production was induced by lactose but repressed by glucose and galactose. The lactase from EPEC which was partially purified by ammonium sulphate precipitation and gel permeation chromatography had a molecular weight of 56 kD and apparent Km of approximately 2.78 mM for lactose. The lactase exhibited optimum activity at pH7.0 at 40°C and was stimulated by Mg2+, Mn2+, Na+ and inhibited by Ba2+, Ca+, Cu2+. EDTA, iodo acetic acid (IAA) and Hg2+ and U2+ ions. The higher production of lactase by EPEC may be linked to its pathogenic role in childhood diarrhea.