On-line recognition of physiological state in a yeast fed-batch culture

The physiological states with respect to cell growth and ethanol production in a yeast led-batch culture can be recognized on-line by fuzzy inferencing. The error vector is newly defined in a macroscopic elemental balance equation and utilized for the on-line recognition of the physiological state of the microorganisms. Fuzzy membership functions are constructed from the error vectors and state recognition is performed successfully by fuzzy inferencing. In particular, a usual physiological state for yeast cultivation in which aerobic ethanol production is accompanied by very low cell growth can be recognized accurately.