Study On The Deracemization Of Epoxide As Agent Intermediate By Microbial Processes

(S)-styrene oxide is one of the key starting materials for the synthesis powerful anticancer agent levamisole. The production of (S)-styrene oxide using enzymatic resolution of racemic styrene oxide was studied in the paper. Racemic styrene oxide was employed as the sole carbon source and18strains capable of producing epoxide hydrolase were screened from soil samples collected in several areas throughout China. Chiral HPLC analysis results showed that the strain G7was the best strain producing high enantioselectivity epoxide hydrolase to catalyze the hydrolysis of the racemic racemic to give (S)-styrene oxide with high enantiomeric excess.G716S rDNA was extracted as template and amplified by PCR.16S rDNA sequence was determined by dideoxynucleotide termination method. The sequence was compared with GenBank and the result showed that G7is Bacillus subtilis.Fermentation conditions of strain G7, including carbon source, nitrogen source, ions, pH and culturing time were studied and the optimum conditions were as following:sucrose10g/L, tryptone10g/L, Na2HPO4·12H2O2g/L, KH2PO42g/L, MgSO40.25g/L, CaCl20.11g/L, pH6.5,30℃, culturing for25h. The maximum enzyme activity was reached372.2U/mg under the optimal conditions.The optimization of conversion condition was conducted and the optimum conversion conditions were as follow:styrene oxide10mg/ml, pH7.0,30℃, conversing for20h. The transformation rate of styrene oxide was49.3%with the99.5%e.e value of (S)-styrene oxide.