L-Glutaminase Synthesis by Marine <i>Halomonas meridiana</i> Isolated from the Red Sea and Its Efficiency against Colorectal Cancer Cell Lines

• Main Authors: Yasser S. Mostafa, Saad A. Alamri, Mohammad Y. Alfaifi, Sulaiman A. Alrumman, Serag Eldin I. Elbehairi, Tarek H. Taha, Mohamed Hashem
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Molecules
• Subjects: <i>Halomonas meridian</i>; L-glutaminase; production; 16S rRNA gene; purification; colorectal cancer
• Online Access: https://www.mdpi.com/1420-3049/26/7/1963

L-glutaminase is an important anticancer agent that is used extensively worldwide by depriving cancer cells of L-glutamine. The marine bacterium, <i>Halomonas meridian</i> was isolated from the Red Sea and selected as the more active L-glutaminase-producing bacteria. L-glutaminase fermentation was optimized at 36 h, pH 8.0, 37 °C, and 3.0% NaCl, using glucose at 1.5% and soybean meal at 2%. The purified enzyme showed a specific activity of 36.08 U/mg, and the molecular weight was found to be 57 kDa by the SDS-PAGE analysis. The enzyme was highly active at pH 8.0 and 37 °C. The kinetics’ parameters of <i>Km</i> and <i>Vmax</i> were 12.2 × 10⁻⁶ M and 121.95 μmol/mL/min, respectively, which reflects a higher affinity for its substrate. The anticancer efficiency of the enzyme showed significant toxic activity toward colorectal adenocarcinoma cells; LS 174 T (IC50 7.0 μg/mL) and HCT 116 (IC50 13.2 μg/mL). A higher incidence of cell death was observed with early apoptosis in HCT 116 than in LS 174 T, whereas late apoptosis was observed in LS 174 T more than in HCT 116. Also, the L-glutaminase induction nuclear fragmentation in HCT 116 was more than that in the LS 174T cells. This is the first report on <i>Halomonas meridiana</i> as an L-glutaminase producer that is used as an anti-colorectal cancer agent.