Document Type: Research Paper
Biotechnology Group, Chemical Engineering Department, Tarbiat Modarres University, P.O. Box: 14115-143, Tehran, I.R. Iran.
Ralstonia eutropha accumulates poly(β-hydroxybutyrate) up to 80% of its dry weight (as a carbon and
energy source) and is the best-known PHB producer. Although PHB has many potential applications in medicine, veterinary practice, agriculture and surgery, its high cost limits the widespread use of it. The recent
researches have focused on reducing these costs by optimizing fermentation process. In this study the
Placket Burman experimental design was used to test the relative importance of medium components and
process variables on cell growth and PHB production. The optimum values of the variables, selected as the
best conditions for further studies in the development of a low cost and effective fermentation process for
PHB production, were as follows: initial fructose concentration, 15 g/l; C/N ratio, 7.4; shaking rate, 200 rpm;
fermentation time, 40 h; temperature, 30°C; seed age, 15 h .