Polyhydroxybutyrate Production from Mixture of Corn Germ and Bran by Solid-State Fermentation

Biodegradable polymer of polyhydroxybutyrate (PHB) is an intracellular inclusion that accumulated by certain microorganism under unfavorable growth condition as a carbon and energy reserve. Properties of PHB are similar to polypropylene, and it has been attracted by some different industries. The main problem in achieving the commercial production of this substance is its high final cost. One of the most significant ways to reduce the cost of this valuable biopolymer is the application of high-productivity processes and low-priced raw materials as a substrate. Solid State Fermentation (SSF) is a useful system for production of secondary metabolites using some of the agricultural residues as substrates. This study aims at utilizing the SSF process and microorganism of Wautersia eutropha and investigating the mixture of corn bran and grem as the low-priced substrates in PHB production. Two effective factors including, the composition percentage of substrate and temperature in the production of PHB and enriching the substrate by molasses for the purpose of increasing the productivity of this metabolite in Erlen scale have been evaluated. The maximum PHB production and related productivity at 28 °C and substrate containing 50% corn germ were obtained 3.255 g/kg and 0.045 g/kg/h, respectively.