Optimization of critical medium components for higher phycocyanin holo- subunit production in Escherichia coli using statistical approach

Abstract

To improve phycocyanin holo-α subunit (cpcA) production from Escherichia coliBL21 (DE3) cells, culture medium was screened and optimized using the statistical experimental designs of Plackett-Burman and response surface methodology. In the first step, one-factor-at-a-time method was used to evaluate the effect of carbon sources and nitrogen sources on the yield of cpcA. A two-level Plackett-Burman design was then adopted to select the most important nutrients influencing the cpcA production, which showed that beef extract, KH2PO4 and K2HPO4·3H2O were the most significant ingredients (P< 0.05). Finally, response surface Box-Behnkendesign was employed to develop a mathematical model to identify the optimum concentrations of the key components for higher cpcA production, which revealed these as follows: beef extract (2.22%, w/v), KH2PO4 (0.52%, w/v), K2HPO4·3H2O(0.94%, w/v). The high correlation between the predicted and observed values indicated the validity of the model. CpcA yield increased significantly with optimized medium (47.62 mg/L) when compared with original medium (2.72 mg/L). Key words: Phycocyanin holo-α subunit, Plackett-Burman design, optimization, response surface methodology.