Enhanced production of glutaminase-free l-asparaginase by marine Bacillus velezensis and cytotoxic activity against breast cancer cell lines

Abstract

Abstract Background The increasing rate of breast cancer globally requires extraordinary efforts to discover new effective sources of chemotherapy with fewer side effects. Glutaminase-free l -asparaginase is a vital chemotherapeutic agent for various tumor malignancies. Microorganisms from extreme sources, such as marine bacteria, might have high l -asparaginase productivity and efficiency with exceptional antitumor action toward breast cancer cell lines. Results l -Asparaginase-producing bacteria, Bacillus velezensis isolated from marine sediments, were identified by 16S rRNA sequencing. l -Asparaginase production by immobilized cells was 61.04% higher than that by free cells fermentation. The significant productivity of enzyme occurred at 72 h, pH 6.5, 37°C, 100 rpm. Optimum carbon and nitrogen sources for enzyme production were glucose and NH4Cl, respectively. l -Asparaginase was free from glutaminase activity, which was crucial medically in terms of their severe side effects. The molecular weight of the purified enzyme is 39.7 KDa by SDS-PAGE analysis and was ideally active at pH 7.5 and 37°C. Notwithstanding, the highest stability of the enzyme was found at pH 8.5 and 70°C for 1 h. The enzyme kinetic parameters displayed Vmax at 41.49 μmol/mL/min and a Km of 3.6 × 10−5 M, which serve as a proof of the affinity to its substrate. The anticancer activity of the enzyme against breast adenocarcinoma cell lines demonstrated significant activity toward MDA-MB-231 cells when compared with MCF-7 cells with IC50 values of 12.6 ± 1.2 μg/mL and 17.3 ± 2.8 μg/mL, respectively. Conclusion This study provides the first potential of glutaminase-free l -asparaginase production from the marine bacterium Bacillus velezensis as a prospect anticancer pharmaceutical agent for two different breast cancer cell lines. How to cite: Mostafa Y, Alrumman S, Alamri S, et al. Enhanced production of glutaminase-free L-asparaginase by marine Bacillus velezensis and cytotoxic activity against breast cancer cell lines. Electron J Biotechnol 2019;42. https://doi.org/10.1016/j.ejbt.2019.10.001 .