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 (/> < 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 msi for lactose. The lactase exhibited optimum activity at pi I 7.0 at 40°C and was stimulated by Mg:+, Mn2+, Na* and inhibited by Ba2*, Ca+, Cu2+. EDTA, iodo acetic acid (IAA) and IIg2 + and U2+ ions. The higher production of lactase by EPEC may be linked to its pathogenic role in childhood diarrhoea.