The enantioselective catalytic hydrolysis of racemic 1,2-epoxyoctane in a batch and a continuous process

In this study, the effect of the two co-solvents, acetonitrile (MeCN) and ethanol (EtOH), on the solubility of 1,2-epoxyoctane (epoxide), and on the reactivity of the catalytic hydrolysis to 1,2-octanediol (diol) by Rhodosporidium toruloides was investigated for final application in a flow-through bioreactor. The solubility of epoxide increased exponentially with the addition of both EtOH and MeCN. However, this increased solubility was at the cost of the reactivity of the enzyme, which showed a decrease with increasing co-solvent concentration, most predominant for MeCN. At 20% EtOH the solubility increased from about 6 to 10 mM, while the initial reaction rate has approximately halved, however, without loss in selectivity. When increasing the epoxide concentration (from 2 to 100 mM) at 20% EtOH, there is an initial linear increase in the initial production rate of the diol (Vdiol) which reaches a plateau at 40 mM. There is a dip in Vdiol at around 9 mM, indicating the possible effect of the one- and two-phase system. In the flow-through bioreactor, a %ee of 35 and 46% was achieved for the (S)-epoxide and (R)-diol, respectively.