The Screening, Identificating And Ion Beam Mutagenizing Of The Microbial Strains For Enantioselective Separation Of Ibuprofen And Studying The Characterization Of The Lipase

The pre-screening and rescreening were used to isolate the strain which was high preference for enantioselective hydrolysis of S-ibuprofen ethyl-ester to the corresponding S-ibuprofen. It was identificated by studying the physiological and biological characteristics and determining the large-subunit (26S) rDNA gene D1/D2 domain sequences of the strain. The result showed that the strain T was Trichosporon lactis.Low energy N+ ion beam(implanted with 30 keV, 1-5 X 10~15ions/cm~2) mutant strain, Trichosporo. lactis K1 showed high preference and genetic stability during hydrolysis of S-ibuprofen ethyl-ester to the corresponding S-ibuprofen.The optimal cultivation conditions were 1.0% starch, 1.0% peptone, 1.0% com steep liquor, 0.5% tween, 1.0% yeast extract respectively. The optimal action temperature was 28℃ and the optimal pH was 7.5 ~ 8.0. The optical substrate concentration was 4%.The rotation and the ee% of S-ibuprofen product were +54.1 ° and 98%, respectively. The characteristics of the product hydrolyzed by K1 were the same as standard S-ibuprofen.Through a serial study of the dissolve doxygen(DO) and pH during the fermentation, it was found that the concentration of the DO and pH changed regularly in 10L fermentor. The pH level may be a good state in dicator of the fermentation process. It was also found that the lowest DO concentration was less than 10% during the fermentation, and the concentration of DO affected the hydrolysis yield seriously. Increasing the concentration of DO was available to improve the yield.It was lipase that hydrolyzed ibuprofen ethyl-ester to the correspondingS-ibuprofen and the lipase of Trichosporon lactis K1 did not release into fermentation liquor. The optimal action temperature of the lipase was 28. The lipase was rather stable in the range of pH7.5~10.5 and the optimal pH was 7.5—8.0. The enzyme activity was inhibited by Cu2+, Pe*\ Fe1+. Mg'\ Ca l* didn't affect the enzyme activity. The isoelectric point of lipase was 3.5 and the molecular weight was 29870.