| Previously grown cells of the ethanologenic bacterium Zymomonas mobilis produce sorbitol and gluconic acid, in reactions catalysed by the periplasmic enzymes glucose-fructose oxidoreductase (GFOR) and glucono-delta-lactonase (GL). The GFOR/GL system activity, in cells to be used in this bioconversion, depends on growth conditions. In batch runs, with initial glucose concentrations (S0) from 42 to 230 g/L, the highest specific and total GFOR/GL activities were obtained with S0 = 153 g/L (12.6 U/g cells and 62 U/L). Higher S0 led to decreasing activities in fresh cells. With S0 = 209 g/L, the final specific activity was only 7.0 U/g. After disruption of cells, however, an activity over 15 U/g was revealed. Since growth inhibition with S0 over 153 g/L was... |
