A NOVEL CONCEPT OF BIOREACTOR - SPECIALIZED FUNCTION 2-STAGE CONTINUOUS REACTOR, AND ITS APPLICATION TO LACTOSE CONVERSION INTO LACTIC-ACID

From reactors performing a continuous production of an inhibitory meta bolite like lactic acid, high product concentrations are obtained only at very low dilution rates. For such systems, volumetric productivity may be improved with the help of a novel two-stage reactor equipped w ith a separate feeding line in the second stage. By pumping a medium o ptimized for growth in the first stage and not controlling the pH of t his reactor, an active seed culture (containing a small concentration of lactic acid) was prepared in continuous mode; this inoculum and a m edium optimized for lactic acid production were fed in the second stag e. Since 97% of the total amount of lactic acid was produced in the se cond stage, the system has been called 'specialized function two-stage reactor'; the volumetric productivity obtained from this novel config uration was close to batch one in similar conditions.