A KINETIC-MODEL AND STEADY-STATE ANALYSIS FOR POLYSACCHARIDE PRODUCTION BY METHYLOMONAS-MUCOSA

A kinetic model for Methylomonas mucosa includes specific rates of growth and polysaccharide formation vs. methanol concentration, that show a maximum and a minimum, respectively. Because of the nonmonotonicity of the specific growth rate, there are two nontrivial steady states, one stable and the other unstable, for a single continuous stirred tank bioreactor (CSTBR). The cell growth is favored at stable steady states while polysaccharide yields are favored at unstable steady states. These phenomena favor a system of two CSTBRs in series, in which the first bioreactor is operated at a stable steady state to feed a constant supply of cells to the second bioreactor for polysaccharide production. It is shown that such a system can be made naturally stable and that the polysaccharide yield can be maintained high at dilution rates much above the maximum specific growth rate for a single bioreactor. © 1990.