L(-LACTIC ACID PRODUCTION BY REPEATED BATCH CULTURE OF RHIZOPUS-ORYZAE IN AIRLIFT BIOREACTOR())

L(+)-Lactic acid production using Rhizopus oryzae was investigated by varying the inoculated spore concentration in preculture medium. The s pore concentration affected mycelial morphology from dispersed filamen tous to pellet form. When the inoculated spore concentration was 2 x 1 0(6) spores/ml in flask culture, a small pellet was formed in the cult ure, which yielded the highest (98.2 g/l) L(+)-lactic acid concentrati on after 48 h culture; when concentration was 2 x 10(5) spores/ml, clu mped and compacted mycelia were observed, which caused a decrease the L(+)-lactic acid concentration (85.7 g/l) after 48 h culture. Followin g in air-lift bioreactor culture, the morphology was similar to that i n flask culture, and when the inoculated spore concentration was 2 x 1 0(6) spores/ml in the seed culture broth, the productivity of L(+)-lac tic acid was 1.07 g/l/h after 48 h culture. The pellet morphology made it possible to perform 9 cycles of repeated batch culture over 14 d. During the first 6 cycles, the average productivity was 2.02 g/l/h, wh ich was 1.9 fold higher than that from batch culture.