S. Westgate et al., HIGH SPECIFIC ACTIVITY OF WHOLE CELLS IN AN AQUEOUS-ORGANIC 2-PHASE MEMBRANE BIOREACTOR, Enzyme and microbial technology, 22(7), 1998, pp. 575-577
Whole Bacillus subtilis cells can catalyze stereoselective hydrolysis
of menthyl acetate in a small-scale two-phase membrane bioreactor. A l
ayer of cells was deposited on one side of a 0.2 mu m microporous nylo
n membrane and then neat liquid racemic menthyl acetate was circulated
past the same side. This organic phase was pressurized slightly relat
ive to the aqueous buffer which flowed past the other face of the memb
rane. No breakthrough or cell detachment was observed over 24 h operat
ion. The total reaction rate reached a maximum with a cell layer of ab
out 40 mu m, then declined far thicker layers. The specific activity (
per unit biomass) at the maximum was about five times higher than with
the same cells in an emulsion reactor. This probably reflects continu
ous good contact with both phases. (C) 1998 Elsevier Science Inc.