Decarboxylation of ferulic acid to 4-vinylguaiacol by Bacillus pumilus in aqueous-organic solvent two-phase systems

Whole cells of Bacillus pumilus were used to catalyze the decarboxylation of ferulic acid to vinylguaiacol in aqueous 0.1 M phosphate pH 6.8 buffer-organic solvent two-phase systems. Highest biotransformation yields were obtained when hydrocarbons such as npentane, n-hexane, n-heptane, and n-octane were used as organic phases, The optimal volume ratio of buffer to organic solvent was 1.0. Fedbatch and lower incubation temperature strategies were explored to enhance the synthesis of vinylguaiacol by reducing substrate inhibition. Maximum productivity (1.52 g l(-1) h(-1) of vinylguaiacol was obtained in a fedbatch operation at 37 degrees C where ferulic acid concentrations were maintained between 2-7 g l(-1). The highest level (9.6 g l(-1)) of vinylguaiacol with a productivity of 0.96 g l(-1) h(-1) was obtained in a whole cell reaction at 25 degrees C in a phosphate buffer:hexane two-phase system. (C) 1998 Elsevier Science Inc.