Partial purification and characterisation of a lipase from Lactobacillus plantarum MF32

Abstract

A lipase from Lactobacillus plantarum MF32 has been partly purified and characterised. The apparent molecular weight of the lipase was estimated to be approximately 75 000. Isoelectric focusing resulted in two separate bands corresponding to pI values of 7·50 and 7·60, respectively. The enzyme has been shown to contribute to sensory quality and reduced production time of fermented dry sausages. Temperature optimum was 37°C with tributyrin as substrate and 41°C with lard as substrate, the overall activity of the lipase being about three times higher with tributyrin as substrate than with lard. Enzyme activity of the lipase was detectable at pH 4·5 and pH 12, with a pH optimum around 9·3 for both substrates. The enzyme activity was only slightly affected by salt concentrations up to 5% NaCl. The temperature dependence of the enzyme as described by the Arrhenius equation with tributyrin as substrate showed a ΔH 298 1 (inactivation) of 186 kJ/mol. The activation of the enzyme appears nonlinear with increasing temperature, probably due to changes in availability of the substrate with temperature.