Proteus Sp. Lipase Displayed On Escherichia Coli Cell Surface And Its Application In Biodiesel Production

It has potential economic value for using lipase to as catalyst for biodiesel production.However,the high price and easily being inactivated in organic solvent restrict industrialization of this technology.The technology of Surface display of lipase can reduced the price of lipase because the separation and purification of proteins is not required.In this paper,the Proteus sp.lipase displayed on the surface of E.coli by using sfGFP as an anchoring motif.Furthermore,we has studied the enzymatic properties of the displayed lipase and applied it to transesterification.The main results of this study were summarize d as follows:1.Proteus sp.lipase displayed on the surface of E.coli Rosetta-Blue by using sfGFP as anchor protein for the first time.The lipA had been fused to the C-term of sfGFP and the vector pETsfGFP constructed using pET-23a and sfGFP in our lab.The recombinant plasmid was named as pETsfGFP-LipA,which was transformed into E.coli Rosetta-Blue for the expression of fusion protein.2.The lipase displayed on the cell surface was confirmed by immunofluorescence microscopy and flow cytometric analysis.3.The optimum temperature and pH for the displayede lipase was 37? and 8,respectively.Triton X-100 can activate the displayed lipase,and it retained 73%and 117%of its original activity after incubation in 60%methanol and ethanol for 18h.4 We studied the production of biodiesel from soybean oil or palm oil and short-chain alcohols by LipA catalytic.Under the condition of adding isooctane,soybean oil or palm oil as the substrate,methanol or ethanol as acyl receptor,the ratio of alcohol to oil should be 5:1 or 3.5:1,the reaction was conducted fo 24h at 37?.The conversion rate of fatty acid methyl ester from palm oil is 57%,the conversion rate of fatty acid methyl ester from soybeans is 43%.