Industrial Biotransformations

Reductase
Aureobasidium pullulans SC 13849
1) Reaction conditions
[1]: 0.017 M, 5 g · L –1 , [288.38 g · mol –1 ] in methanol
[1]: 25 g · L –1glucose pH: 6.8–7.0
T: 28 °C
medium: aqueous
reaction type: reduction
catalyst: frozen whole cells
enzyme: reductase
strain: Aureobasidium pullulans SC 13849
CAS (enzyme): [9025-57-4]
2) Remarks
● In a two-stage process: cells were grown in a 25-L bioreactor for 40 h and then harvested by
centrifugation and stored at –60 °C until further use. Frozen cells were suspended in 50 mM
potassium phosphate buffer (pH 6.8) and the resulting cell suspensions were used to carry out
bioreduction.
● At the end of the reaction, hydroxy ester was adsorbed onto XAD-16 resin after filtration. It
was recovered in 94 % yield from the resin by acetonitrile extraction.
● The recovered (R)-hydroxy ester was treated with Chirazyme L-2 or pig liver esterase to convert
it into the corresponding (R)-hydroxy acid in quantitative yield. The enzymatic hydrolysis was
used to avoid the possibility of racemization under chemical hydrolytic conditions.
● A simpler, single-stage fermentation-bioreduction process was also developed. A yield of 98 %
and ee of 98 % were obtained. However, owing to low cell concentration in this single-stage
process, the reaction was completed in 107 h compared with 16 h for the two-stage process.
3) Flow scheme
Not published.
1 2
1 = 2-oxo-2-(1',2',3',4'-tetrahydro-1',1',4',4'-tetramethyl-6'naphthalenyl)acetate
2 = 2-(R)-hydroxy-2-(1',2',3',4'-tetrahydro-1',2',3',4'-tetrahydro-
1',1',4',4',-tetramethyl-6'-naphthalenyl)acetate
Fig. 1.1.X.X – 1
O
O
OEt
E1
OH
O
OEt
EC 1.1.X.X
Bristol-Myers Squibb
197