Copper nanoparticles biosynthesis by Priestia megaterium and its application as antibacterial and antitumor agents

Abstract

The growth of material science and technology places high importance on creating better processes for synthesizing copper nanoparticles. Thus, an easy, ecological, and benign process for producing copper nanoparticles (CuNPs) has been developed using Priestia sp. bacteria utilizing a variety of low-cost agro-industrial wastes and byproducts. The biosynthesis of CuNPs was conducted using glucose medium and copper ions salt solution, then it was replaced by utilizing low-cost agro-industrial wastes. UV-visible spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), High-resolution transmission electron microscope (HR-TEM), Attenuated Total Reflectance and Fourier transform infrared (ATR-FTIR), and zeta potential were used to characterize the biosynthesized CuNPs. The cytotoxicity of CuNPs using Vero -CCL-81 cell lines, and antibacterial and antitumor properties using human colon epithelial colorectal adenocarcinoma Caco-2-HTB-37 cell lines were assessed. The UV-visible and DLS studies revealed CuNPs formation, with a maximum concentration of 6.19 ppm after 48 h, as indicated by a 0.58 Surface plasmon resonance (SPR) within 450 nm and 57.73 nm particle size. The 16S rRNA gene analysis revealed that Priestia sp. isolate is closely related to Priestia megaterium and has been deposited in the NCBI GenBank with accession number AMD 2024. The biosynthesis with various agro-industrial wastes indicated blackstrap sugar cane molasses being the most effective for reducing CuNPs size to 3.12 nm owing to various reducing and stabilizing active compounds. The CuNPs were free of contaminants, with a sphere-shaped structure and a cytotoxicity assessment with an IC₅₀ of 367.27 μg/mL. The antibacterial activity exhibited by the most susceptible bacteria were Bacillus cereus ATCC 11788 and Staphylococcus aureus ATCC 6538 with inhibition zones of 26.0 mm and 28.0 mm, respectively. The antitumor effect showed an IC₅₀ dose of 175.36 μg/mL. Based on the findings, the current work sought to lower product costs and provide a practical solution to the environmental contamination issues brought on by the buildup of agricultural wastes. In addition, the obtained CuNPs could be applied in many fields such as pharmaceuticals, water purification, and agricultural applications as future aspects.

Keywords: Priestia megaterium; Agro-industrial wastes; Antibacterial effect; Antitumor activity; Caco-2-HTB-37 cell line; Copper nanoparticles; Cytotoxicity activity.

Fig. 1

(a) The alteration in color, signifying the production of Priestia sp. CuNPs changed the mixture's reaction color from pale yellow to greenish, (b) The SPR spectrum at 0.58, and (c) DLS characterization for CuNPs formation after 48 h at 30 °C using shaking flasks at 150 rpm.

Fig. 2

(a) Match score for Priestia sp. isolate showing 99% similarity to Priestia megaterium, (b) Phylogenetic-tree of Priestia megaterium.

Fig. 3

Dynamic light scattering (DLS) characterization of biosynthesized P-CuNPs diameter size by P. megaterium, affected by various agro-industrial wastes and byproducts after 48 h at 30 °C using shaking flasks at 150 rpm.

Fig. 4

(a) Time course for P-CuNPs biosynthesized using blackstrap sugarcane molasses at 30 °C using shaking flasks at 150 rpm , (b) The obtained powder of P-CuNPs after optimization with blackstrap sugarcane molasses.

Fig. 5

TEM characterization of P-CuNPs utilizing blackstrap sugarcane molasses after 48 h at 30 °C in shaking flasks at 150 rpm.

Fig. 6

(a) X-ray diffractometer (XRD) characterization of P-CuNPs, (b) The FTIR analysis of the active compounds responsible for the reduction, coating, and stabilization of P-CuNPs in P. megaterium cell free extract, and (c) The FTIR analysis P-CuNPs, (d) Zeta potential analysis of P-CuNPs using blackstrap sugarcane molasses after 48 h at 30 °C using shaking flasks at 150 rpm.

Fig. 7

Antibacterial activity of P-CuNPs against the most sensitive pathogenic strains, (a) S. aureus, (b) B. cereus.

Fig. 8

(a) Microscopic images of the morphological changes in Vero-CCL-81 cell lines, and (b) The IC₅₀ of P-CuNPs on ccl-81 cell lines.

Fig. 9

(a) Microscopic images of the morphological changes by P-CuNPs as antitumor agent in ATB-37 cell lines, and (b) The IC₅₀ of P-CuNPs as antitumor agent on Caco-2-HTB-37 cell lines.