产环氧化物水解酶菌种的筛选及发酵条件优化

以外消旋苯基环氧乙烷为唯一碳源，从土壤中筛选出编号为G7的菌株，能选择性水解外消旋苯基环氧乙烷而得到(S)-苯基环氧乙烷，对映体过量值(e.e)达到99.3%。经鉴定菌种G7属于枯草芽胞杆菌。对该菌株的发酵条件进行了优化，结果表明，当培养基成分为蔗糖10g/L，胰蛋白胨10g/L，Na₂HPO₄·12H₂O 2g/L，KH₂PO₄ 2g/L，MgSO₄ 0.2g/L，CaCl₂ 0.01g/L，pH 6.5，30℃培养25h，环氧化物水解酶活力达到最高值372.2U/mg。

Isolation of a bacterium producing epoxide hydrolase and optimization of fermentation conditions

A bacterial strain G7 producing highly enantioselective epoxide hydrolase was isolated from soil. The enantiomeric excess (e.e) value of the styrene oxide formed was 99.3%. G7 was identified as Bacillus subtilis by comparing its 16S rDNA sequence with data in GenBank. Fermentation conditions for strain G7, including carbon source, nitrogen source, other ions, pH and culture time were studied and the optimum conditions were found to be as follows: sucrose 10g/L, tryptone 10g/L, Na₂HPO₄·12H₂O 2g/L, KH₂PO₄ 2g/L, MgSO₄ 0.2g/L, CaCl₂ 0.01g/L, pH6.5, 30℃, culture time of 25h. The maximum observed enzyme activity was 372.2U/mg under the optimal conditions. 