Immobilization of Brevibacterium Cells for the production of l-glutamic acid

Studies were performed to elucidate the optimal conditions (gel concentration, bead size, initial biomass, storage period) for immobilization of growing cells of Brevibacterium sp. (DSM 20411) in alginate and agar gels and to evaluate the immobilized biocatalyst in batch mode, and continuous mode in a packedcolumn bioreactor, for l-glutamic acid production. The entrapped cells were also cultivated for fwenty five days in five repeated batches (each batch lasted for five days). Maximum l-glutamic acid production in batch and repeated-batch modes was 7.4 and 8.7 mglml, respectively, with alginate beads, and 11.8 and 13.3mg/ml, respectively, with agar beads. Under optimized conditions (flow rate, initial cell loading), l-glutamate productivity was maintained within a range 10–11 mg/ml for two weeks, in continuous mode, in a packed column bioreactor with agarimmobilized cells.