Optimization of enzyme production conditions and enzymatic properties of cold-adapted and organic solvent-tolerant lipase from Burkholderia sp.JXJ-16

Enzyme production conditions for Burkholderia sp. JXJ- 16 producing cold- adapted and organic solvent- tolerant lipase were optimized by signal factor analysis to maximize lipase production.A maximum lipase production was obtained after20 h fermentation of 20 m L of medium containing sucrose 3.75 g / L,urea 11.25 g / L,K_2HPO_42 g / L,( NH4)2SO_41 g / L,Mn SO40.25 g / L,and lard emulsion 2.5%( v / v) at an initial p H9.0 in 250 m L Erlenmeyer flask with 3% inoculum at 30 ℃.The crude JXJ- 16 lipase preferentially catalyzed the p- nitrophenyl esters of different fatty acids with medium chains,and its best substrate was p- nitrophenyl caprylate.The optimal reaction temperature for the crude lipase was 35 ℃,and it remained better stability at temperatures ranging from 30 to 60 ℃.The optimum hydrolytic activity of the crude lipase was observed at p H8.5 to9.0,and it exhibited better stability at p H5.0 to 10.5.The activity of the crude lipase was activated by Na~+,Mg~(2+),Ca~(2+),Mn~(2+),and EDTA,respectively,whereas inhibited by Zn~(2+),Cu~(2+)and Fe~(3+),respectively.Moreover,K+had no remarkable effect on its activity.The crude lipase had high tolerance and enhanced activity in the presence of different concentration of isopropyl alcohol,methanol,acetone,ethyl acetate,chloroform,benzene,and n- hexane,respectively,except ethanol and acetonitrile. In a word,the strain JXJ-16 could utilize cheap raw materials as a fermentation medium to achieve the optimal lipase production,and its cold- adapted alkaline lipase had better temperature and p H stability and showed high tolerance to most of the tested organic solvents.