Screening, Purification And Characterization Of The Lipase Produced By Serratia Sp. SL-11

A strain of lipase producing bacterium was isolated form soil on beibei.lt is ide -ntified as Serratia by 16srDNA sequence analyse and named as Serratia sp.SL-11.Factors affecting the Serratia sp.SL-11 lipase production were investigated in sh -ake flask level. Obtained result showed that the optimum medium composition and cultural condition were(%): soybean powder 4.0 ,sucrose0.5,olive oil 1.0, K₂HPO₄0.2, NaH₂PO₄,MgSO₄-7H₂O 0.1 ,Tween80 0.5 and nitialize pH was 8.0,30℃, 200r/min shaking,for 22h.Under such conditions the lipase activity in culture supernatant was 2-3 times high as the original one.The lipase was purified to consisted of sequential ultrafiltration, ion-exchange chromatography on DEAE-Sepharose and superdex200 gel-chromatography. Obtained two lipase sample ,named as SLP-1 and SLP-2. and its specific activity was 6609.15U/mg and 5770.50U/mg;purified 40.67-fold and 35.08-fold. Yield was 20.9% and 3.3%.some character of the enzyme are also in identified, The optimum temperature of lipase SLp-1 is 50°C and the optimum pH is 9.0.The molecular weight of the purified lipase SLp-1 is about 319KD, inferior molecular is about 74.9KD;The optimum temperature of lipase SLp-2 is 47℃ and the optimum pH is 9.0.The molecular weight of the purified lipase SLp-1 is about 377KD, inferior molecular is about 77.6KD.The another lipase was keenness to metal- ion , the enzyme activity isstimulated byMn2\ Ga2\ Mg2+evidence, but SLP-2 is inhibited by Co\ Fe2+. It indicated that lipases from Serratia sp.SL-11.would be applied widely as it showed high thermostabilities and stabilities of wide pH range.