On‐line measurement of gas‐exchange conditions in fermentation processes

Abstract

Abstract Gas‐exchange conditions of C. ulilis cultures were analyzed by an on‐line, real‐time operating digital computer interfaced with a 250 liter, highly instrumented fermentor. Information obtained from the computer was correlated with wet chemical analytical data related to nucleic acid, protein, and ethyl alcohol production rates. Once the correlation was established, the computed gas‐exchange data, especially the RQ which functions as an indicator of the cells physiological condition, could be used as a real‐time process status indicator which follows or forecasts events during the fermentation. It was also found that electrical noises generted on the sensor‐instrument level may handicap the interpretation of the meaning of computed process status indicators. Since “clear” data is considered as a prerequisite to follow the physiological conditions and perform control of environmental variables, a special computer program is necessary to filter the electric noises at the sensor‐instrument level prior to the on‐line, real‐time data analysis for process status identification.