Abstract
Long-chain fatty acids are widely used in food and chemical industries, and the enzymatic preparation of fatty acids is considered an environmentally friendly process. In the present study, long-chain fatty acids were prepared by the enzymatic hydrolysis of rapeseed oil with a genetically engineered lipase. Because thermophilic lipase has strong stability at higher temperatures, it was more suitable for the industrial production of long-chain fatty acids. Therefore, the thermophilic lipase BTL2 from Geobacillus thermocatenulatus was efficiently expressed in E. coli BL21(DE3) cells with an enzyme activity of 39.50 U/mg followed by gene codon optimisation. Experimental results showed that the recombinant lipase BTL2 exhibited excellent resistance to certain organic solvents (n-hexane, benzene, ethanol, and butanol). The metal cation Ca(2+) and the non-ionic surfactant Triton-100X enhanced enzyme activity by 7.36% and 56.21% respectively. Moreover, the acid value of the liberated long-chain fatty acids by hydrolysing rapeseed oil was approximately 161.64 mg KOH/g at 50 °C in 24 h, the hydrolytic conversion rate was 91.45%, and the productivity was approximately 6.735 mg KOH/g h. These results suggested that the recombinant lipase BTL2 has excellent hydrolytic performance for rapeseed oil and showed great potential for the enzymatic preparation of long-chain fatty acids.