牛乳中荧光假单胞菌耐热性脂肪酶的活性影响因素

Isolation and Identification of Thermostable Lipase Produced by Pseudomonasfluorescens from Fresh Milk

以新鲜牛乳中分离到的荧光假单胞菌为研究对象,对其分泌产生的耐热性脂肪酶进行纯化,并研究不同温度、pH值、Ca^(2+)质量浓度对该脂肪酶活性的影响。结果表明:经过初步纯化的脂肪酶分子质量为55kD,纯度为91.5%,并且发现该耐热性脂肪酶在50℃、30min,63℃、30min,72℃、20s,90℃、10min,121℃、0.1MPa、20min处理之后,相对酶活力分别为75.02%、86.21%、73.25%、17.62%、13.63%;并且该脂肪酶的最适温度为63℃,最适pH值为8.0;在荧光假单胞菌体外,Ca^(2+)质量浓度对荧光假单胞菌脂肪酶的活力并无显著影响。

In the present study,a preliminary purification was carried out to obtain heat-resistant lipase secreted by Pseudomonas fluorescens separated from fresh milk.Moreover,the effects of temperature,pH,and Ca2＋ concentration on the activity of this lipase were determined.Results showed that the lipase from Pseudomonas fluorescens had a molecular weight 55 kD and a purity of 91.5％ after the purification,and its relative activity was 75.02％,86.21％,73.25％,17.62％ and 13.63％ after heat treatment at 50 ℃ for 30 min,63 ℃ for 30 min,72 ℃ for 20 s,90 ℃ for 10 min,and 121 ℃,0.1 MPa for 20 min,respectively.The optimum reaction pH and temperature for this enzyme were 8.0 and 63 ℃,respectively.The lipase activity was not significantly affected by Ca2＋ concentration.