Improved enzymatic two-phase biotransformation for (R)-phenylacetylcarbinol: Effect of dipropylene glycol and modes of pH control |
| |
| Authors: | Noppol Leksawasdi Peter L Rogers |
| |
| Institution: | 1. Department of Food Engineering, Faculty of Agro-Industry, Chiang Mai University, Chiang Mai, 50100, Thailand;2. School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia;3. School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia |
| |
| Abstract: | An octanol/aqueous two-phase process for the enzymatic production of (R)-phenylacetylcarbinol (PAC) has been investigated further with regard to optimal pH control and replacement of 2.5?M MOPS buffer by a low cost solute. The specific rate of PAC production in the 2.5?M MOPS system controlled at pH?7 was 0.60?mg?U?1?h?1 (reaction completed at 34?h), a 1.6 times improvement over the same 2.5?M MOPS system without pH control (0.39?mg?U?1?h?1 at 49?h). An improved stability of PDC was evident at the end of biotransformation for the pH-controlled system with 84% residual carboligase activity, while 23% of enzyme activity remained in the absence of pH control. Lowering the MOPS concentration to 20?mM resulted in a lower benzaldehyde concentration in the aqueous phase with a major increase in the formation of by-product acetoin and three times decreased PAC production (0.21?mg?U?1?h?1). Biotransformation with 20?mM MOPS and 2.5?M DPG as inexpensive replacement of high MOPS concentrations provided similar aqueous phase benzaldehyde concentrations compared to 2.5?M MOPS and resulted in a comparable PAC concentration (92.1?g?L?1 in the total reaction volume in 47?h) with modest formation of acetoin. |
| |
| Keywords: | Biotransformation enzyme activity organic-aqueous two-phase system (R)-phenylacetylcarbinol pyruvate decarboxylase pH control |
|
|
