Frequency analysis of autonomously oscillating yeast cultures

Measurements of state variables from oscillating chemostat cultures of Sacc haromyces cerevisiae were analyzed by Fourier transformation. Of the signal s tested, carbon dioxide and oxygen in the exit gas stream and dissolved ox ygen in the medium, all gave identical results. Analysis of data from react ors operated at fixed conditions showed that after oscillations start, they pass through an extended transient lasting several days, before the oscill ation period becomes constant. Under transient operating conditions, Fourie r analysis revealed expected qualitative trends in the change of oscillatio n period with dilution rate. (C) 2000 Elsevier Science Ltd. All rights rese rved.