微生物酯酶是一种广泛应用于食品、医药和精细化工等领域的工业化酶。为了丰富酯酶资源，本文通过提取我国传统发酵食品环境样品总基因组DNA，构建宏基因组文库，从中筛选获得一个新的酯酶基因（est_115），该基因全长948 bp，编码316个氨基酸，其蛋白序列同源性分析，表明与来自Pseudomonas lutea的羧酸酯水解酶同源性最高为38%，显示酯酶Est_115属于新的酯酶类。然后构建了est_115基因重组表达载体，在大肠杆菌BL21(DE3)中获得表达，经纯化得到重组酯酶Est_115。酶学性质的分析表明，该重组酯酶Est_115对酰基碳链较短的对硝基苯酚酯具有较高的催化活性，最适作用温度为35 ℃，最适pH值为7.0，在10%~18% NaCl条件下，酶蛋白可保持较高的催化活性，具有良好的耐盐性，提示该酶可以应用在高渗透压食品加工中，是一个新型的极具潜力的酯酶。

Microbial esterases play an important role in food, pharmaceutical, and fine chemicals industries. In order to enrich available esterase resources, metagenomic DNA was extracted from traditional food fermentation environment, and the metagenomic library was constructed. An esterase gene (est_115) was obtained after screening of the library; it contained 948 bp and encoded a protein of 316 amino acids (AA). Sequence homology analysis showed that its protein had the highest homology (38%) with the carboxylic-ester hydrolase from Pseudomonas lutea, indicating that esterase Est_115 was a new type of esterase. Subsequently, a recombinant expression vector containing the est_115 gene was constructed and expressed in Escherichia coli BL21 (DE3), and the recombinant esterase Est_115 was obtained after purification. Analysis of its enzymatic properties indicated that recombinant esterase Est_115 showed a relatively high catalytic activity on p-nitrophenyl esters with a short carbon chain on their acyl group, and the optimal temperature and pH value were 35°C and 7.0, respectively. Under conditions of 10~18% sodium chloride, the esterase could maintain a high catalytic activity, and showed good salt resistance, which suggested that this new type of esterase enzyme could be used in food processing using high osmotic pressure.

国家自然科学基金青年科学基金项目（31500102)；广东轻工职业技术学院创新强校工程专项资金项目（2A21005、1A20105、1A10605、2A10905、1A20201）；广东高校特色调味品工程技术开发中心建设项目（GCZX-B1103）