Coconut-water as fermentation medium for enzyme production (4): Time-profiled control of batch 5L stirred tank fermentation

Abstract

The use of coconut-water as a cheap fermentation medium for the production of the enzyme cytochrome p-450 by the yeast Saccharomyces cerevisiae N.C.Y.C 754 was investigated in a 5L stirred tank fermenter by building state variable models and generating optimum control time-profiles for the control variables temperature (T), pH and agitation rate (RPM) Using Pontryagin's Continuous Maximum Principle. The theoretical maximum enzyme yield that can be achieved under optimum timeprofiled control of the three variables is 694.87 nmol L-1 in 30.5 hours of fermentation. Except for T, the continuous optimum time-profiles of the variables do not differ significantly from that of set point control. Experiments conducted with the three variables controlled along these time-profiles gave an average yield of 633.70 nmol L-1 in 28 hours of fermentation