Silver Nanoparticles Synthesis From Bacillus subtilis and Its ROS-Mediated Staphylocidal Activity Against...

Area of Science:

• Nanotechnology
• Microbiology
• Materials Science

Background:

• Antimicrobial resistance (AMR) in Staphylococcus aureus, including MRSA and VRSA, poses a significant global health threat, complicating treatment in clinical settings.
• The rise in drug-resistant infections, particularly in middle-income countries, is exacerbated by high hospitalization rates and improper antibiotic use, leading to increased morbidity and mortality.
• Nanotechnology offers innovative solutions for combating acute and chronic microbial infections, with silver nanoparticles (AgNPs) showing particular promise.

Purpose of the Study:

• To synthesize silver nanoparticles (AgNPs) using a green chemistry approach with Bacillus subtilis cell-free extract.
• To characterize the synthesized AgNPs using various spectroscopic and imaging techniques.
• To evaluate the antimicrobial efficacy of AgNPs against multidrug-resistant pathogens, including methicillin-resistant Staphylococcus aureus (MRSA).

Main Methods:

• Green synthesis of AgNPs using Bacillus subtilis cell-free extract.
• Characterization of AgNPs via UV-VIS, FT-IR, SEM, TEM, zeta potential, XRD, and EDX analysis.
• Antimicrobial efficacy testing against Gram-negative and Gram-positive bacteria, including MRSA, determining minimum inhibitory concentration (MIC), and assessing bactericidal effects through ROS production, macromolecule leakage, and biofilm inhibition.

Main Results:

• Characterization confirmed the successful synthesis of AgNPs.
• AgNPs demonstrated significant antimicrobial potency against MRSA with a minimum inhibitory concentration (MIC) of 0.4 mg/mL and were effective against other tested pathogens.
• AgNPs exhibited bactericidal effects by inducing reactive oxygen species (ROS) production and macromolecule leakage, and effectively inhibited biofilm formation by up to 82% at 1.6 mg/mL concentration.

Conclusions:

• Green synthesized AgNPs possess potent antimicrobial activity against a broad spectrum of bacterial pathogens, including drug-resistant strains like MRSA.
• The antimicrobial mechanism involves increasing cellular susceptibility through ROS generation and promoting DNA and protein leakage.
• AgNPs effectively inhibit bacterial biofilm formation, highlighting their potential to combat the growing challenge of antimicrobial resistance in Staphylococcus aureus infections.