菌株Serratia marcescens SYBC08产过氧化氢酶液态发酵工艺的优化及酶性质研究

Optimization of Fermentation Conditions for Catalase by Serratia marcescens SYBC08 and Characterization of Its Crude Enzyme

利用单因素筛选和正交试验对菌株Serratia marcescens SYBC08液态发酵产酶的培养基和条件进行了优化,其最优工艺为:柠檬酸25 g/L,玉米浆粉36 g/L,初始pH值为6.75,接种量为体积分数4%,装液量50 mL,转速250 r/min,35℃培养36 h产酶活力可达9 553 U/mL,是优化前的5.49倍。通过对硫酸铵沉淀得到的过氧化氢酶进行酶学性质研究,该酶在碱性条件(pH值为9.0)条件下,60℃下保温150 min酶活力几乎不变,65℃半衰期为150 min,其比商品化的牛肝过氧化氢酶具有更高的热稳定性。该酶最佳催化温度是20℃,在0℃依然展示了78%的活力。这些结果表明该酶具有良好的冷适应和热稳定性,在高温、碱性条件或极低温条件有应用潜力。

The nutrient and environmental conditions for catalase production by Serratia marcescens SYBC08 were optimized with single factor experiment and orthogonal design in this study.The optimum conditions were listed as follows： 25 g/L citric acid,36 g/L corn steep liquor powder,initial pH 6.75,liquid volume 50 mL/250 mL flask,4% inoculation,35 ℃,250 rpm,for 36 hours.With the optimum conditions,the catalase titer achieved at 9553 U/mL,which was 5.49-fold than that of the control.Properties of the catalase after purification by ammonium sulfate precipitation were studied.At 60 ℃ and pH 9.0,the enzyme was stable for 150 min;at 65 ℃ and pH 9,the half-life of the enzyme was approximately 150 min;its thermo stability was higher than that of commercial catalase from bovine.It was also active at 20 ℃ and had 78% of its activity at 0 ℃.These results suggest that the enzyme displays a property with cold adaption and thermo stability,and it has potential applications in high-temperature,alkaline and low-temperature conditions.