Reduced pressure gas phase bioreactor as a tool for stereoselective reduction catalyzed by alcohol dehydrogenase from Parvibaculum lavamentivorans

• The immobilized ADH activity was represented in reduced pressure gas phase reactor.
• The immobilized ADH activity was measured by using various reaction parameters.
• The immobilized ADH activity under reduced pressure was compared with that under standard pressure.
• The catalytic activity of the immobilized ADH was evaluated by the kinetic analysis.

This study presents an immobilized alcohol dehydrogenase reaction in the gas phase under reduced pressure. The catalytic ability (activity, stereoselectivity and productivity) of alcohol dehydrogenase from Parvibaculum lavamentivorans was investigated as a function of various factors for process design. The reduction of 4-methyl-2-pentanone to (R)-4-methyl-2-pentanol with concomitant regeneration of cofactor using 2-propanol as cosubstrate was employed as a model reaction. Under reduced pressure the catalytic ability of the immobilized enzyme was efficiently exhibited, similar to that under standard pressure. On the other hand, the dependence of the water and substrate activities as well as the reaction temperature on the catalytic ability of the immobilized enzyme remained almost the same, compared to the standard pressure. Based on the kinetic parameters (maximum reaction rate and Michaelis constant) estimated, the enzyme activity was found to be effectively maintained under reduced pressure. These findings indicate that the reduced pressure gas phase reactor is capable of proceeding enzyme reaction for chiral compound production. However, as the future scope, the reaction system which proceeds with the catalytic ability of enzyme enhanced more in the reduced pressure condition needs to be widely investigated.