Heat‐induced overexpression of the thermophilic lipase from Bacillus thermocatenulatus in Escherichia coli by fermentation and its application in preparation biodiesel using rapeseed oil

Abstract Due to its simple, less by‐product and environment friendly properties, enzymatic transesterification of oil with short‐chain alcohol to biodiesel, fatty acid methyl esters (FAMEs) is considered to be a promising way of green production and has attracted much attention. In this study, FAMEs were synthesized by an enzymatic method with recombinant lipase as catalysts. A thermophilic Bacillus thermocatenulatus lipase 2 (BTL2) was overexpressed in Escherichia coli BL21(DE3) through relative and quantitative analysis using real‐time quantitative PCR. The results suggested that the BTL2 gene was overexpressed in E. coli at the mRNA level, and the recombinant strain harboring a high‐copy number vectors was selected and applied to fermentation to produce BTL2 with enzyme activity of 35.54 U/mg cells. The recombinant BTL2 solution exhibited excellent resistance to neutral pH, high temperature, and organic solvents after a certain treatment. Finally, the effects of enzymatic transesterification for preparing biodiesel were studied, using rapeseed oil as raw material, as well as BTL2 solution as catalysts, which resulted in 86.04% yield of FAMEs under 50°C for 36 h. The liquid BTL2 was directly used to prepare FAMEs at a higher temperature efficiently, making the thermophilic BTL2 had the potential application value in biodiesel reproduction subsequently.