Optimization of L-asparaginase type II produced by Bacillus velezensis SE114

Document Type : Research Paper


1 Department of Microbiology, Falavarjan branch, Islamic Azad University, Esfahan, Iran.

2 Department of Biology, Falavarjan branch, Islamic Azad University, Esfahan, Iran.


Once the acute lymphoblastic leukemia cells that need L-asparagine are exposed to L-ASNase, they die because of the limitations of L-asparagine. As well, the globally rising rate of ALL requires extraordinary efforts to discover new microorganisms with high L-ASNase production and efficiency. The aim of this study is high amount of L-ASNase production. After isolation, the optimization of the L-ASNase production was performed by the response surface methodology and the central composite design. Then, in-silico studies were predicted for the L-ASNase-producing gene. In this study, Bacillus velezensis was isolated as an L-ASNase producer from the slaughterhouse effluent, by the M9 medium. The optimization process further included illustrated Tween 20, glucose, temperature, and L-asparagine, which were more significant for the L-ASNase production, respectively. Based on the statistical prediction by the RSM, more enzyme activity (7.11 U/mL) could be realized at 0.6% Tween 20, 1.7% glucose, 55°C temperature, and 1.8% L-asparagine. The in-silico studies also established that the binding site located at the N-terminal domain and the active site flexible loop. Besides, it contained Thr36, Ala47, Tyr50, Glu84, Asp117, Thr116, Met142, Lys189, Thr193, and Thr192 as the conserved and functional residues in L-ASNase. It was concluded that B. velezensis SE114 was produced L-ASNase type II in the present study. The statistical optimization results also showed that Tween 20, glucose, temperature, and L-asparagine were significant variables affecting the L-ASNase production. In addition, temperature and L-asparagine had noteworthy interactions.


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