Kinetic model for effects of ethanol and phosphate on cell growth and emulsan production inAcinetobacter calcoaceticus RAG-1

Abstract

A mathematical kinetic model was proposed to describe the cell growth and the emulsan production in batch cultivations ofAcinetobacter calcoaceticus RAG-1. Ethanol and phosphate concentrations were chosen as the key variables, which affected the cell growth and emulsan production in the batch cultivations. The cell growth was inhibited by high concentrations of ethanol and was slightly affected by intracellular phosphate level. And the emulsan production was related to the intracellular phosphate level dependent upon the extracellular phosphate concentration. Kinetic model for the cell growth was formulated using the ethanol inhibition term and the intracellular phosphate level. The relationship between extracellular and intracelluiar phosphate level was expressed by the concept of active transport. Kinetic model for the emulsan production was represented using growth-associated term and intracellular phosphate inhibition term. Release of emulsan was presumed as the primary release from the surface of viable cell and the secondary release by cell lysis. The model predicted the experimental results with good agreement.