The culture conditions and nutritional rations influencing the production of extra cellular antileukemic enzyme by novel Enterobacter aerogenes KCTC2190/MTCC111 were optimized in shake-flask culture. Process variables like pH, temperature, incubation time, carbon and nitrogen sources, inducer concentration, and inoculum size were taken into account. In the present study, finest enzyme activity achieved by traditional one variable at a time method was 7.6 IU/mL which was a 2.6-fold increase compared to the initial value. Further, the L-asparaginase production was optimized using response surface methodology, and validated experimental result at optimized process variables gave 18.35 IU/mL of L-asparaginase activity, which is 2.4-times higher than the traditional optimization approach. The study explored the E. aerogenes MTCC111 as a potent and potential bacterial source for high yield of antileukemic drug.

Acute lymphocytic leukemia (ALL) is an outrageous disease worldwide. l-Asparagine (l-Asn) and l-Glutamine (l-Gln) deamination play a crucial role in ALL treatment. Role of Elspar® (l-asparaginase from Escherichia coli) in regulation of l-Asn and l-Gln has been confirmed by the other researchers through experimental studies. Therapeutic research against ALL remained elusive with the lack of information on molecular interactions of Elspar® with amino acid substrates. In the present study, using different docking tools binding cavities, key residues in binding and ligand binding mechanisms were identified. For the apo state enzyme and ligand bound state complexes, MD simulations were performed. Trajectory analysis for 30 ns run confirmed the kinship of l-Asn with l-asparaginase enzyme in the dynamic system with less stability in comparison to l-Gln docked complex. Overall findings strongly supported the bi-functional nature of the enzyme drug. A good number of conformational changes were observed with 1NNS structure due to ligand binding. Results of present study give much more information on structural and functional aspects of E. coli l-asparaginase upon the interaction with its ligands which may be useful in designing effective therapeutics for ALL.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-015-0339-9) contains supplementary material, which is available to authorized users.

Physical and chemical factors influencing the anti-leukemic l-asparaginase enzyme production by were optimized using multi-stage optimization on the basis of preliminary experimental outcomes obtained by conventional one-factor-at-a-time approach using shake flasks. Process variables namely carbon, nitrogen sources, pH and temperature were taken into consideration during response surface methodology (RSM) optimization. The finest enzyme activity of 0.51 IUml obtained by OFAT method was enhanced by 3.2 folds using RSM optimization. Artificial neural network (ANN) modelling and genetic algorithm (GA) based optimizations were further carried out to improve the enzyme drug yield. Results were also validated by conducting experiments at optimum conditions determined by RSM and GA optimization methods. The novel bacterium yielded in 2.88 IUml of enzyme activity at optimum process variables determined by GA optimization, i.e., 0.5% glucose, 8.0% beef extract, 8.3 pH and 49.9 °C temperature. The study explored the optimized culture conditions for better yielding of anti-leukemic enzyme drug from a new bacterial source namely .

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