SCL-LCL-PHA copolymer production by a local isolate, Pseudomonas aeruginosa MTCC 7925

A five-level-four-factor central composite rotary design (CCRD) was employed in combination with response surface methodology (RSM) to optimize the process variables for the production of a novel copolymer consisting of short-chain-length (SCL) and long-chain-length (LCL) PHA units, i.e., P(3HB-3HV-3HHD-3HOD) copolymer in Pseudomonas aeruginosa MTCC 7925. The four variables involved in this study were ethanol, glucose, ammonium nitrate (NH(4)NO(3)), and potassium dihydrogen phosphate (KH(2)PO(4)). A second-order polynomial equation was obtained by multiple regression analysis using RSM. The statistical analyses of the results showed that all the four variables had significant impact on the copolymer yield. The model predicted a maximum yield of 81.1% of dry cell weight (dcw) on setting the concentrations of ethanol and glucose at 1.5 and 1.1%, and KH(2)PO(4) and NH(4)NO(3) at 2.79 and 1.86 g/L, respectively. Verification of the predicted value resulted into a yield of 77.6% (dcw). This novel copolymer exhibited comparable material properties with polypropylene (PP) and low density polyethylene (LDPE), thus advocating its potential applications in various fields.