Characterization of an alkaline lipase from Proteus vulgaris K80 and the DNA sequence of the encoding gene

Abstract

A facultatively anaerobic bacterium producing an extracellular alkaline lipase was isolated from the soil collected near a sewage disposal plant in Korea and identified to be a strain of Proteus vulgaris. The molecular mass of the purified lipase K80 was estimated to be 31 kDa by SDS-PAGE. It was found to be an alkaline enzyme having maximum hydrolytic activity at pH 10, while fairly stable in a wide pH range from 5 to 11. The gene for lipase K80 was cloned in Escherichia coli. Sequence analysis showed an open reading frame of 861 bp coding for a polypeptide of 287 amino acid residues. The deduced amino acid sequence of the lipase gene had 46.3% identity to the lipase from Pseudomonas fragi.