Kinetics of batch fermentation by planktonic culture. (A) pH, optical density (OD)600nm and glucose consumption; (B) product concentrations during the fermentation process. Initially, experiments were performed in six Duran bottles under the same condition. At 40 h, three of the bottles were supplemented with KA-I resin (final concentration 50 g/L) (open symbol and dashed line), with the other ones left as control (solid symbol and solid line). The mean value (± SD) was calculated from the results of parallel runs. The vertical dashed lines represent the equivalent concentrations adsorbed by the resin (determined by dividing the adsorbed amounts by the volume of the fermentation broth) at the end of the fermentation.