The production of Cephalosporin C by Acremonium chrysogenum 3/2 (0) strain was performed in shake flasks with semisynthetic medium and corn steep liquor (CSL) supplement, after removal of the sediment and the sediment and proteins from the medium, respectively. Product formation was also carried out in shake flasks with semisynthetic media without buffer and with different type of buffers, to avoid the strong fall in pH during cultivation. In addition, cultivations were carried out in 10 and 30 1 bioreactors with semisynthetic medium and pH control in batch operation without and with oxygen supplement. The performances of these cultivations were compared with each other and with cultivations in 301 reactors with complex media in batch and fed-batch operation. Fed-batch cultivations with complex media had the highest performance. Batch cultivations with semisynthetic media and pH control have nearly the same performance as batch cultivation with complex media. Cultivations with semisynthetic media with pH control had a better production than those with buffers. Complex media after removal of the sediment of CSL and after separation of sediments,and proteins of CSL had low performances. Semisynthetic media without buffer had the lowest performance. (C) 2002 Elsevier Science Ltd. All rights reserved.