Screening,Characterization And Application Of Phospholipase From Isolated Strains

Phospholipase,a type of enzyme that hydrolyzes hydratable phospholipids to fatty acids and hydrated phospholipids,it has important applications in many industries,including medicine,food and chemical industry.In this work,phospholipase producing bacteria were screened from soil and identified.The fermentation conditions optimization,enzyme purification and enzyme properities were studied.Finally,the catalytic products of the enzyme were characterized.Firstly,the phospholipase producing strain B8 was screened from the soil,and it was identified as Aspergillus niger by morphological observation and 18 S r DNA sequencing.After the optimization of fermentation conditions of the strain producing phospholipase were identified as:1.5% maltose,0.5% lecithin,1% yeast powder,0.05% Na H2PO4·2H2O,0.10% K2HPO4·3H2O,0.06% Mg SO4·7H2O,and 0.05% Ca Cl2,p H 6.5,the optimum temperature is 30°C,the shaking speed is 220 r/min,the culture time is 4 days.Phosph olipase was isolated and purified from the fermentation broth of Aspergillus niger B8,and the SDS-PAGE showed that the molecular weight of the protein is about 40 k Da.The enzymatic properties of the enzyme are as follows: the optimum temperature is 30°C,the optimum p H is 6.5,and the most suitable substrate is lecithin.Phospholipase activity is promoted by Ca2+ and Mg2+ and strongly inhibited by SDS and EDTA.The phospholipase was catalyzed with lecithin as the substrate,and the conversion rate was about 40%.The product was isolated,purified and characterized,indicating that the product is glyceryl phosphorylcholine.