Living cells of the bacterium Corynebacterium glutamicum were entrapped in polyurethane foams in a vertical rotating immobilized cell reactor. This reactor was used for the continuous production of glutamic acid. The bacterium grew abundantly within the porous structure of polyurethane foams, and it was necessary to control cell growth by manipulating rotation speed and cell leakage into the surrounding medium. The effects of rotation speed, oxygen transfer rate and dilution rate on continuous production of glutamic acid were investigated. During long-term operation, biotin and penicillin may accumulate inside the cells. Simultaneous regulation of their concentration was required to maintain stable, long-term operation.