Growth monitoring and control in complex medium: A case study employing fed‐batch penicillin fermentation and computer‐aided on‐line mass balancing

To broaden the practicality of on‐line growth monitoring and control, its application in fedbatch penicillin fermentation using high corn steep liquor (CSL) concentration (53 g/L) is demonstrated. By employing a calculation method that considers the vagaries of CSL consumption, overall and instantaneous carbon‐balancing equations are successfully used to calculate, on‐line, the cell concentration and instantaneous specific growth rate in the penicillin production phase. As a consequence, these equations, together with a feedback control strategy, enable the computer control of glucose feed and maintenance of the preselected production‐phase growth rate with error less than 0.002 h−1.