Study On Stability,Immobilization And Properties Of Lipase From Marine Microorganism YS2071

Lipase(EC 3.1.1.3)is an enzyme which can catalyzes the hydrolysis of long chain glycerides.The unique interface activation characteristics and stereoselectivity of lipases make them have a wide range of applications in organic synthesis,food nutrient composition improvement and bio-energy and other industries.Yeast,bacteria and fungi can produce lipase.The lipase studied in this paper is an alkaline lipase derived from marine microorganism YS2071.The stability of the liquid enzyme of this lipase was studied and a stabilizer formulation was obtained.The lipase was immobilized using polystyrene microspheres.Optimization of immobilization conditions and research of the nature of the immobilized enzyme were did.The results of the study are summarized as follows:Study on the stability of liquid lipase: Using temperature-accelerating method,various factors affecting the stability of liquid lipase activity of marine microorganism YS2071 were researched.The inactive mechanical model of the enzyme was studied.The additive for improving the stability of enzyme activity was optimized.Through orthogonal experiment,a better formulation of the composite stabilizer was obtained.The formulation was: 6 % of glycerin,9 % of sorbitol,9 % of fructose,1.7 % of sodium benzoate,15 mM of calcium chloride,0.5 % of potassium sorbate.The most stable pH is 9.Stabilizer long-term test showed that the enzyme activity retention rate of liquid lipase YS2071 after leaving for 90 days at 25 °C was 91.29 % after adding the stabilizer formulation,and the enzyme activity retention rate increased by 70.1 % compared to the controlsample without the protective agent added.It greatly improved the stability of the liquid lipase.Immobilization of lipase by physical adsorption of polystyrene microspheres: A series of polystyrene microspheres with different functional groups and different particle sizes were tested for lipase immobilization.The results showed that the amino polystyrene microspheres whose particle size is 0.6-1 ?m had the best immobilization effect.This kind of amino polystyrene microsphere was selected for the immobilization of lipase.The optimal conditions for lipase immobilization using the amino polystyrene microspheres were as follows: enzyme concentration 5 mg/mL,pH 10,temperature 20 ?,curing time 6 h,and shaking rate 250 rpm/min.The final enzyme activity recovery reached42.82 %.Studies on immobilized lipase performance: Compared with the free enzyme,the stability of the immobilized lipase was significantly enhanced,especially the temperature stability and pH stability.The tolerance of metal ions and organic solvents was significantly improved.Storing for 30 days,the enzyme activity retention rate was increased by15.09% compared with free enzyme,After repeated using 5 times of immobilized enzyme,the relative enzyme activity still retained 63.77 %,and after repeated using 10 times,the relative enzyme activity still retained29 %.There is more good operational stability.