Bioproduction of chiral mandelate by enantioselective deacylation of alpha-acetoxyphenylacetic acid using whole cells of newly isolated Pseudomonas sp. ECU1011.
Substrate-directed screening was carried out to find bacteria that could deacylate O-acetylated mandelic acid from environmental samples. From more than 200 soil isolates, we identified for the first time that Pseudomonas sp. ECU1011 biocatalytically deacylated (S)-alpha-acetoxyphenylacetic acid with high enantioselectivity (E > 200), yielding (S)-mandelic acid with 98.1% enantiomeric excess (ee) at a 45.5% conversion rate. The catalytic deacylation of (S)-alpha-acetoxyphenylacetic acid by the resting cell was optimized using a single-factor method to yield temperature and pH optima of 30 degrees C and 6.5, respectively. These optima help to reduce the nonselective spontaneous hydrolysis of the racemic substrate. It was found that substrate concentrations up to 60 mM could be used. 2-Propanol was used as a moderate cosolvent to help the substrate disperse in the aqueous phase. Under optimized reaction conditions, the ee of the residual (R)-alpha-acetoxyphenylacetic acid could be improved further, to greater than 99%, at a 60% conversion rate. Furthermore, using this newly isolated strain of Pseudomonas sp. ECU1011, three kinds of optically pure analogs of (S)-mandelic acid and (R)-alpha-acetoxyphenylacetic acid were successfully prepared at high enantiomeric purity.
Ju
Xin
X
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, People's Republic of China.
Yu
Hui-Lei
HL
Pan
Jiang
J
Wei
Dong-Zhi
DZ
Xu
Jian-He
JH
D000215:Acylation; D001426:Bacterial Proteins / Q000378:metabolism; D055162:Biocatalysis; D001709:Biotechnology / Q000379:methods; D004950:Esterases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008333:Mandelic Acids / Q000737:chemistry / Q000378:metabolism*; D010648:Phenylacetates / Q000737:chemistry / Q000378:metabolism*; D011549:Pseudomonas / Q000145:classification / Q000166:cytology* / Q000201:enzymology* / Q000302:isolation & purification; D012988:Soil Microbiology; D013237:Stereoisomerism; D013379:Substrate Specificity; D013696:Temperature
D001426:Bacterial Proteins; D008333:Mandelic Acids; D010648:Phenylacetates; D004950:Esterases; C037938:mandelic acid