Lactate production in an integrated process configuration: reducing cell adsorption by shielding of adsorbent

The problem of binding of microbial cells to an adsorbent matrix during in situ recovery of bioproducts from a fermentation broth has been addressed by shielding the adsorbent with a thin layer of a non-ionic polymer. Extractive bioconversion of lactic acid by integrating ion-exchange adsorption with the fermentation stage was studied. The effect of coating of the ion-exchanger with agarose on product recovery and cell adsorption was evaluated. Extractive fermentation with both uncoated and coated resin resulted in an increase in reactor productivity as compared to the normal fermentation. The free cell density in the system with agarose-coated beads was similar to that in control fermentation, but was significantly lower in the system with the uncoated ion-exchanger. Electron microscopic scanning of the bead surface after passage of the fermentation broth showed cells attached to the native adsorbent but not to the coated one.