Cell surface display of Staphylococcus haemolyticus L62 lipase in Escherichia coli and its application as a whole cell biocatalyst for biodiesel production

Staphylococcus haemolyticus L62 (SHL62) lipase was displayed on the cell surface of Escherichia coli using an autotransporter protein of Pseudomonas putida EstAβ8 as an anchoring motif. Localization of the SHL62 lipase on the cell surface of E. coli was confirmed by immunofluorescence microscopy, flow cytometry analysis, Western blot, protease accessibility, and whole-cell enzyme activity assays. SHL62 lipase activity of whole cells reached 168 U/g dry cell weight toward p-nitrophenyl caprylate after being induced by 0.1 mM IPTG for 24 h. The optimum temperature and pH of the displayed SHL62 lipase was 40–45 °C and pH 10, respectively. The displayed SHL62 was stable up to 45 °C, at which it had >80% of maximum activity. The displayed SHL62 lipase showed a preference for medium chain fatty acids of p-nitrophenyl esters. Moreover, the displayed SHL62 lipase was used as a whole cell catalyst to produce biodiesel that was obtained at a yield of nearly 89.4% after a 96 h reaction at 30 °C. These results suggest that the displayed SHL62 lipase on the cell surface of E. coli using an EstAβ8 anchoring motif can be used for biocatalytic applications.