Observer-based non-linear control of a fed-batch autoinductive fermentation process

Abstract

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 synthesis. It is shown that in the last stage the substrate concentration should be maintained constant. This is achieved using an input—output linearizing controller accompanied by a novel non-linear state observer for the estimation of unmeasured state variables on the basis of on-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 as the effectiveness and robustness of the overall control system.