Effect of phase composition on the bioconversion of methyltestosterone in a biphasic system

Abstract The bioconversion of methyltestosterone to methandienone by Arthrobacter simplex AS.1.94* was selected as model system for evaluating the effect of solvent nature and aqueous phase composition on the biocatalytic efficiency in aqueous–organic two-phase system. A series of organic solvents with varying log  P oct values, together with five different aqueous media, were selected as organic and aqueous phase. Tween-80 and menadione were added as surfactant and an external electron acceptor, respectively. The effect of volumetric phase ratio on biocatalytic activity was also investigated. The results showed that selection of organic phase must take a series of factors into account. The composition of the aqueous phase markedly influenced biocatalytic yields, particularly the addition of the menadione. In the system with carbon tetrachloride as the organic phase and phosphate buffer as aqueous phase, the volumetric phase ratio of 3 org :7 aq was feasible.