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

Abstract

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 KH 2PO 4 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, KH 2PO 4 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% KH 2PO 4 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%).