Biofunctionalization of Silver Nanoparticles With Lactonase Leads to Altered Antimicrobial and Cytotoxic Properties

Background: N-acylated homoserine lactone lactonase which cleave the Acyl homoserine lactone molecules produced by biofilm-forming pathogens and silver nano-particles (AgNPs), are known for their antibacterial effect against several Gram-positive and Gram-negative bacteria. In this study, AgNPs were coated with N-acylated homoserine lactonase protein (AgNPs-AiiA) isolated from Bacillus sp. ZA12. Results: The AgNPs-AiiA complex was characterized by UV-visible spectra, Dynamic light Scattering, Fourier transform infrared spectroscopy (FTIR), and Field Emission Scanning Electron Microscope (Fe-SEM). The synthesized nano-particles were found to be spherical in shape and had an approximate size of 22.4 nm. Treatment with AiiA coated AgNPs showed a significant reduction in exopolysaccharide production, metabolic activity, cell surface hydrophobicity of bacterial cells, and anti-biofilm activity against multidrug-resistant K. pneumoniae as compared to treatment with AiiA protein and neat AgNPs. AgNPs-AiiA complex exhibited potent antibiofilm activity at sub-optimal concentration of 14.4 μg/mL without being harmful to the macrophages and to the various tissues including kidney, liver, spleen and lungs of BALB/c mice upon intra-venous administration. Conclusion: It is concluded that at a concentration of 14.4 μg/mL, AgNPs coated with AiiA kill bacteria without harming the host tissue and provides a suitable template to design novel anti-biofilm drug to circumvent the issue of drug resistance.