Inhibition of biofilm, quorum‐sensing, and swarming motility in pathogenic bacteria by magnetite, manganese ferrite, and nickel ferrite nanoparticles

Abstract Resistance to antibiotics by pathogenic bacteria constitutes a health burden and nanoparticles (NPs) are being developed as alternative and multipurpose antimicrobial substances. Magnetite (Fe 3 O 4 np), manganese ferrite (MnFe 2 O 4 np) and nickel ferrite (NiFe 3 O 4 np) NPs were synthesized and characterized using thermogravimetric analysis, transmission electron microscopy, Fourier transformed infra‐red, and X‐ray diffraction. The minimal inhibitory concentrations (MIC) ranged from 0.625 to 10 mg/mL against gram‐positive ( Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212), gram‐negative ( Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) and candida ( Candida albicans ATCC 10239 and Candida tropicalis ATCC 13803) species. The NPs exhibited violacein inhibition against Chromobacterium violaceum CV12472 of 100% at MIC and reduced to 27.2% ± 0.8% for magnetite NPs, 12.7% ± 0.3% for manganese ferrite NPs and 43.1% ± 0.2% for nickel ferrite NPs at MIC/4. Quorum‐sensing (QS) inhibition zones against C. violaceum CV026 were 12.5 ±0.6 mm for Fe 3 O 4 np, 09.1 ± 0.5 mm for MnFe 3 O 4 NP and 17.0 ± 1.2 mm for NiFe 3 O 4 np. The NPs inhibited swarming motility against P. aeruginosa PA01 and biofilm against six pathogens and the gram‐positive biofilms were more susceptible than the gram‐negative ones. The NiFe 2 O 4 np had highest antibiofilm activity against gram‐positive and gram‐negative bacteria as well as highest QS inhibition while Fe 3 O 4 NP had highest biofilm inhibition against candida species. The synthesized magnetic NPs can be used in developing anti‐virulence drugs which reduce pathogenicity of bacteria as well as resistance.