Anticancer, antioxidant and antibacterial potential of L-Glutaminase (Streptomyces roseolus strain ZKB1) capped silver and zinc oxide nanoparticles and its molecular characterization

Abstract The current investigation reports anti-cancer, antioxidant and antibacterial potential of L-Glutaminase (Streptomyces roseolus strain ZKB1) and L-Glutaminase capped nanoparticles. The highest L-Glutaminase production of 9.57 U/mL was achieved on the 4th day of fermentation when L-Glutamine was used as the sole carbon and nitrogen source. Enhanced recycling stability was observed after 6 cycles using L-Glutaminase immobilized in 3% agar and agarose matrices. Free and immobilized L- Glutaminase showed K m of 13.89 ± 0.8 and 7.13 ± 0.3 mM and V max of 18.40 ± 1.5 and 24.21 ± 1.7 U/mg respectively. L- Glutaminase capped silver (AgNP) and zinc oxide (ZnONP) nanoparticles were synthesized and structurally characterized using UV visible spectroscopy, FTIR, SEM–EDS, XRD and AFM. L- Glutaminase capped AgNP and ZnONP exhibited good thermal stability with five and three stages weight loss pattern respectively based on TGA. L-Glutaminase capped AgNP exhibited highest inhibitory activity against B. subtilis (45 $$\pm$$ ± 0.5 mm) and E. coli (33 $$\pm$$ ± 0.8 mm) whereas, L-Glutaminase capped ZnONP demonstrated highest inhibition against E. coli (30 $$\pm$$ ± 0.3 mm) and B. cereus (25 $$\pm$$ ± 0.5 mm). Increased nanoparticles concentration exhibited increased inhibitory potential as compared to wild L-Glutaminase and lowest MIC of 0.09 µg/mL was exhibited against B. cereus. L-Glutaminase capped nanoparticles demonstrated significant antioxidant properties through in-vitro ABTS and DPPH radical scavenging assays in a dosage-dependent manner. L-Glutaminase and capped AgNP and ZnONP, demonstrated pronounced cell cytotoxicity against MCF-7 cancerous cell line with 57.17 µg/mL, 8.13 µg/mL and 28.31 µg/mL IC50 values respectively, suggesting promising properties as anticancer agents in enzyme-based therapy. The results reveal promising biological activities with potential applications in healthcare sector. Graphical Abstract