Cloning, Expression, and Characterization of an Esterase Gene from Traditional Food Fermentation Environment Metagenomic DNA
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Abstract:
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.
