2006, Vol.13, pp.29-36

A turbidostat is a continuous bioreactor in which the biomass concentration level is controlled by regulation of the dilution rate. In this paper, the behaviour of an aerobic Saccharomyces Cerevisiae culture in a turbidostat regulated by a PI feedback controller is discussed. In particular, it will be shown how the cybernetic model of Jones & Kompala [1], based on the competition among oxidative and fermentative metabolic pathways and capable of describing some dynamic features of the system, can predict the presence of chaotic regimes in a specific range of operating parameters of the controller. The transition to chaos is determined by period doubling and intermittency according to Feigenbaum scenario, but the shift among different metabolic routes causes some unusual behaviours of the periodic windows.
Key words: turbidostat, chaotic oscillations, yeasts, cybernetic model

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