Abstract
The substrate specificities and reaction conditions for the microbial oxidation of higher alcohols in isooctane were investigated using Rhodococcus equi cells grown on n-tetradecane as the sole carbon source. Primary alcohols, C4-C14 (even numbers), were oxidized to the corresponding carboxylic acids, with which the substrate alcohols further combined to form esters, and various kinds of secondary decanols were oxidized to the corresponding ketones, suggesting that the substrate specificities of R. equi were not so restricted in isooctane. As to the reaction conditions, water was positively required for the oxidation of hjgher alcohols such as 1-tetradecanol in organic solvents such as isooctane, although the amount of water required represented only a small portion of the reaction mixture. On the other hand, ester formation took place in isooctane practically free from water, and the rates of ester formation from 1-tetradecanol and tetradecanoic acid by dried cells increased with an increase in temperature up to 70°C in isooctane, while ester formation hardly occurred at 70°C when intact cells were used in place of dried cells. It was thus suggested that microbial ester formation is less susceptible to thermal inactivation in the absence of water than in its presence.
