OBSERVER-BASED NONLINEAR CONTROL OF A FED-BATCH AUTOINDUCTIVE FERMENTATION PROCESS

Optimal regulatory control of an autoinductive recombinant culture in a fed-batch reactor is considered. End point optimization results in a three-stage process: biomass growth, inducer synthesis and product sy nthesis. It is shown that in the last stage the substrate concentratio n should be maintained constant. This is achieved using an input-outpu t linearizing controller accompanied by a novel non-linear state obser ver for the estimation of unmeasured state variables on the basis of o n-line off-gas carbon dioxide concentration measurements. Experimental runs of luminous recombinant E. coli strain in a laboratory fermenter demonstrate the rapid convergence of the observer estimates as well a s the effectiveness and robustness of the overall control system.