Isolation and identification of a lipase producing psychrotrophic bacteria from soil: Cloning and partial characterization of its lipase

Abstract

Lipases are serine hydrolases and catalyze both the hydrolysis and synthesis of long-chain triacylglycerols. Lipases have great importance since their wide usage in industry. Lipases are produced by microorganisms (bacteria and fungi), plants and animals. However, microbial lipases, especially from bacteria, more useful than their plant and animal derivatives because of several important properties. The primary goals of this thesis were to isolate and identify a lipase producing bacterium from soil sample from Erciyes mountain in Kayseri by 16S rRNA sequence analysis, find the sequence of lipase gene by degenerate PCR and inverse PCR and analyze of lipase gene for some important features like active site residues. The other purposes of this study were determination of lipase production conditions like optimum production time, partial purification and characterization of native lipase enzyme. Purification was performed by ammonium sulfate precipitation and gel filtration. Spectrophotometric lipase assay was used for enzyme characterization. As conclusion, a lipase producer bacterium was isolated from soil using rhodamine B-olive oil plate assay and identified as a strain of Pseudomonas fluorescens based on 16S rRNA sequence homology. Its partial lipase gene was obtained and it was suggested that the lipase belong to group 3 Pseudomonas lipases according to gene and amino acid homology search. Moreover, native lipase partially purified and characterized. The molecular mass of purified lipase was estimated to be approximately 43 kDa by SDS-PAGE. The optimum temperature and pH for the lipase were found to 45°C and pH 8, respectively.