Bio-control potentials of Vachellia nilotica-derived silver nanoparticle against multidrug-resistant Staphylococcus haemolyticus strains from raw milk

Abstract

Abstract The global rise in multidrug-resistant (MDR) microorganisms has led to an increased need for innovative and more effective antimicrobials. Green nanotechnology is a promising therapeutic. This study examined the biocontrol efficacy of synthesized Vachellia nilotica leaf extract-silver (Ag) nanoparticles (NPs) against three previously isolated environmental MDR Staphylococcus haemolyticus strains: MKU1, MKU2, and MKS3. The disc diffusion method was utilized to test the efficacy of AgNPs against these isolates, while broth microdilution was employed to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Synthesized NPs were analyzed using ultraviolet–visible (UV–vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and electron microscopy. The effects of the AgNPs on the cell membrane of the test organisms, nucleic acid, and protein were also examined. The UV–vis absorption spectra showed a surface plasmon resonance peak of 456 nm, indicating carbon–neutral synthesis of AgNPs. FTIR spectroscopy indicated that peptides and flavonoids reduced precursors into NPs and stabilized them. XRD showed particle crystalline structures. Transmission and scanning electron microscopy confirmed the spherical form of the synthesized NPs. Based on transmission electron microscopy, the average size of the NPs is 61 nm. The MIC and MBC for antibacterial action were 2.5 and 5 mg/mL, respectively. Zones of inhibition ranged from 7.00 ± 0.57 mm at 0.625 mg/mL to 30.00 ± 0.82 mm at 10 mg/mL. Cell protein leakage, DNA, and membrane damage were found in AgNP-treated bacterial cells. This study revealed that AgNPs may be effective against MDR Staphylococcus species with the potential to have significant benefits to public health.

Keywords

• Antimicrobial resistance
• Alternative medicine
• Food pathogen
• Food safety and security
• Green synthesis
• Vachellia nilotica