一种氨基甲酸乙酯与尿素降解酶产生菌的鉴定及酶学特性

从小鼠消化系统中筛选到一株能产生氨基甲酸乙酯（EC，Urethane）降解酶的菌株，16S rDNA序列分析和生理生化鉴定确定为Providencia sp.。酶底物特异性研究表明，该酶对尿素和氨基甲酸乙酯都有相对强的降解作用，而对一些酯类和氨基酸没有降解作用，该酶对两种底物的最适作用pH值均为4.5左右，最适温度均为35 ℃。单因素实验优化了培养基配方，在最佳培养条件下，酸性EC降解酶酶活从0.32 U/mL提高到0.63 U/mL，酸性脲酶酶活从0.87 U/mL提高到1.95 U/mL。初步应用研究表明，该酶在黄酒的复杂体系中仍然能有效的降解尿素和EC，且对黄酒中的风味物质几乎影响。
A strain capable of producing urethanase was isolated from the mouse intestines and identified as Providencia sp. By analyzing the 16S rDNA sequence and conducting the physiology and chemistry experiment. The substrate specificity experiment showed that the enzyme can catalyze both urea and urethane with the optimal pH of 4.5 and optimal temperature of 35 ℃ but had no influence on the ester and amino acid. The fermentation condition was optimized based on single factor experiment. Under the optimal condition, the acid urethanase activity was increased from 0.32 U/mL to 0.63 U/mL and acid urease activity from 0.87 U/mL to 1.95 U/mL. The crude enzyme can effectively decompose the urea and EC in the Chinese rice wine and has little effect on the flavor components