An efficient process for producing L-lactic acid using an, EDF method is described. The results showed that intermittent EDF with continuous medium feed was the best one among the experiment methods employed. Comparing with the conventional EDF, intermittent EDF (seven on-off) with continuous medium feed indicated that the maximum value of o.d.(660) was not increased, but productivity was 1.5 times higher. The yield increased by above 30% and glucose transport decreased to 1/10 (from 0.46 to 0.05). (C) 2003 Elsevier Ltd. All rights reserved.