摘要
氨基甲酸乙酯是发酵食品天然产生的1种2A级致癌物。建立以氨基甲酸乙酯脱氨酶为基础的生物清除方法,在食品安全方面具有重要意义。利用单因素比较方法,通过测定比酶活,对氨基甲酸乙酯脱氨酶的发酵条件和酶学性质进行研究。结果表明,氨基甲酸乙酯的最适发酵条件是:以15.0 g/L麦芽糖为碳源,5.0 g/L NH4Cl+5.0 g/L酵母膏为氮源,7.5 g/L氨基甲酸乙酯,培养温度28℃,起始pH 5.5。培养菌株枯草芽孢杆菌ZJ09 30 h后,氨基甲酸乙酯脱氨酶的比酶活达到最大值18.86 U/mL。经盐析、离子交换和膜浓缩后,氨基甲酸乙酯脱氨酶的纯化倍数达到174,冷冻干燥的酶粉比活力为32 186 U/g。氨基甲酸乙酯脱氨酶的最适催化温度45℃,最适反应pH 4.0。该酶具有一定的热稳定性,在酸性环境的催化活力和稳定性较好,适当浓度的Zn2+和Mg2+对酶活有显著促进作用。菌株ZJ09所产氨基甲酸乙酯脱氨酶具有良好的催化能力,易于发酵制备,是一种值得深入研究和开发的食品用酶,具有广泛的产业化应用前景。
Ethyl carbamate,one of 2A carcinogens,presents always in the fermented foods.It is significant to re-move the ethyl carbamate with ethyl carbamate deaminase（ECD）,which catalyze ethyl carbamate to ethyl formate and ammonia.The fermentation and characteristics of ECD were investigated with single-factor test.The optimum culture con-ditions for the strain of Bacillus subtilis ZJ09,which secreted the enzyme of ECD,were 15.0 g maltose,5.0 g NH4 Cl,5.0 g extract of yeast,7.5 g EC in 1 liter medium with the constant temperature of 28 ℃ and initial pH 5.5.The specific activity of ECD was up to 18.86 U/mL when the strain of ZJ09 were cultivated in 30 h.The fermentation broth contained ECD was treated with salting-out,ion-exchange,and ultra-filter membrane.The refined ECD powder was produced through lyophilization with specific activity of 32 186 U/g.ECD had the most activity at the optimum temperature of 45 ℃ and the optimum pH of 4.0.ECD was thermostable when the temperature was under 45 ℃,the catalytic activity was better in acid environment.With the optimum concentrations of Zn2＋and Mg2＋,the activity of ECD was promoted greatly.ECD from the strain of ZJ09 was a potential agency for the removal of EC in fermented food.Simple production and bi-ologic safety promoted the application prospect of ECD.
出处
《中国食品学报》
EI
CAS
CSCD
北大核心
2013年第12期71-77,共7页
Journal of Chinese Institute Of Food Science and Technology
基金
浙江省科技厅重大科技专项(2010C12020-2)
浙江省自然科学基金项目(LY12B06005)
中国博士后科学基金项目(20110491796)
关键词
氨基甲酸乙酯
脱氨酶
发酵条件优化
酶学性质
ethyl carbamate
deaminase
fermentation optimum
enzymatic characteristic
