Production of l-asparaginase from Escherichia coli ATCC 11303: Optimization by response surface methodology

This paper discusses the studies carried out for the optimal production of enzyme l-asparaginase (l-asparagine amidohydrolase, EC 3.5.1.1) from Escherichia coli (ATCC 11303). It was found that inoculum age of 18 h and inoculum size of 10% were the most favorable operating conditions for enzyme production. Lactose, yeast extract and KH2PO4 were found to be the best carbon, nitrogen and ion sources, respectively. Statistical method was used to survey how various medium conditions affect the enzyme production. By response surface methodology, the values of lactose, tryptone, yeast extract, KH2PO4 and l-asparagine concentration were investigated to obtain the maximum enzyme activity. The highest enzyme activity, 1.03 U mL−1 enzyme, was determined under the following conditions: 1.08% lactose, 1.79% tryptone, 1.6% yeast extract, 2% KH2PO4 and 0.19% l-asparagine. Response surface methodology proved to be a powerful tool in optimizing the medium and by this method, more than 10-fold (from 0.1 to 1.03 U mL−1) enhancement in l-asparaginase activity was achieved as compared to that obtained in the basal medium (Luria–Bertani media, inoculum age of 24 h and inoculum size of 10%).

Research highlights▶ This paper discusses the study carried out for the optimal production of enzyme l-asparaginase (l-asparagine amidohydrolase,(EC 3.5.1.1) from Escherichia coli (ATCC 11303). ▶ The highest enzyme activity, 1.03 U mL−1 enzyme, was achieved under the following conditions: 1.08% lactose, 1.79% tryptone, 1.6% yeast extract, 2% KH2PO4 and 0.19% l-asparagine. ▶ The significant interaction between yeast extract and tryptone was observed from the response surface and contour plots. ▶ Response surface methodology proved to be a powerful tool in optimizing the medium.