Understanding antimicrobial activity of biogenic selenium nanoparticles and selenium/chitosan nano-incorporates via studying their inhibition activity against key metabolic enzymes.

Microbial metabolic enzymes play a crucial role in several biological processes that have a significant impact on growth and proliferation. Therefore, inhibiting specific key metabolic enzymes can be an applicable approach for developing antimicrobial agents that selectively target pathogens. In the current study, selenium nanoparticles (Se NPs) extracellularly biosynthesized by Nocardiopsis sp. MAR13 and Se NPs incorporated with nano-chitosan (NCh) (Se/Ch-nano-incorporate) were evaluated for their antimicrobial activity against various microbial pathogens such as Salmonella typhi, Proteus vulgaris, Staphylococcus aureus, Escherichia coli, Aspergillus flavus, Aspergillus niger, Rhizoctonia sp., Candida albicans ATCC10231. The synthesized Se NPs, and Se/Ch-nano-incorporate were characterized by UV-Vis., FTIR, HRTEM, SEM, EDX, DLS, Zeta potential, and XRD. Additionally, their inhibition activity against microbial metabolic key enzymes, including phosphoglucose isomerase (PGI), pyruvate dehydrogenase (PDH), glucose-6-phosphate dehydrogenase (G6PDH), and nitrate reductase (NR), was assessed. The impact on protein leakage from bacterial cell membranes was also evaluated as a potential mechanism of antimicrobial action. On the other hand, MCF-7 and A549 tumor cell lines, as well as WI-38 normal cell lines, were used to assess their cytotoxic activity. It was found that Se NPs were spherical with a diameter range of 60.2 to 120.2 nm. In contrast, Se/Ch-nano-incorporate had a roughly spherical shape with a diameter range of 21.4 to 32.7 nm and substantially higher stability. Both synthesized agents exhibited strong antimicrobial activity against the most tested microbial pathogens with substantial inhibitory effect on the tested enzymes and notable protein leakage. Furthermore, they showed potent anticancer activity against both tumor cell lines with low cytotoxicity against WI-38 normal cell line. Consequently, Se NPs and Se/Ch-nano-incorporate are highly recommended to be employed as antimicrobial and anticancer agents with promised biosafety, eco-friendliness, and efficacy.