Mathematical Modelling as a Tool to Optimize PHA Production by Massilia spp

Minimum Run Resolution IV screening design was employed to study important process factors to maximize Dry cell weight (DCW) and Polyhydroxyalkanoate (PHA) production by Massilia spp. From screening design, it was observed that maltose, NH4HPO4, Na2HPO4 and K2HPO4 were found to be significantly affecting DCW and PHA production. A three-level-four-factor central composite design (CCD) was employed in combination with response surface methodology (RSM) to optimize the concentration of screened factors. The statistical analysis of results showed that maltose and NH4HPO4 had a positive effect whereas Na2HPO4, K2HPO4 had a negative effect on DCW and PHA production. By using RSM, optimum concentration of significant factors was found to be as follows: maltose: 30.0 g/l, NH4HPO4: 3.0 g/l, Na2HPO4: 3.0 g/l, K2HPO4: 3.0 g/l. Verification of the predicted value resulted into a yield of 25.5 g/l of DCW and 6 g/l of PHA.