Applied Microbiology and Biotechnology, Vol.100, No.16, 7161-7170, 2016
Evaluation of AgClNPs@SBA-15/IL nanoparticle-induced oxidative stress and DNA mutation in Escherichia coli
The bactericidal effects of silver nanoparticles have been demonstrated in the past years. Recently, the new antimicrobial compounds of silver nanoparticles with different formulations have been developed. In this work, AgClNPs@SBA-15/IL as a new compound of Ag nanoparticles, was synthesized and characterized by XRD, TEM, SEM, FTIR, and EDX. The antibacterial activity and the molecular mechanism effects of AgClNPs@SBA-15/IL nanoparticles (SNPs) on Escherichia coli DH5 alpha cells were investigated by analyzing the growth inhibitory, H2O2 level, catalase activity, DNA mutation, and plasmid copy number following treatment with AgClNPs@SBA-15/IL nanoparticles. In experimental results, the minimum inhibitory concentration (MIC) was observed in 75 mu g/ml and the antibacterial efficacy (ABE) in CFU analysis was estimated 95.3 %. In bacterial cells treated with 75 and 100 mu g/ml, H2O2 level significantly increased and catalase activity decreased compared with control. The random amplified polymorphic DNA (RAPD) was used to evaluate the effect of AgClNPs@SBA-15/IL nanoparticles in DNA damages and mutation in E. coli genome. RADP-PCR results indicated different banding patterns including appearance or disappearance of bands and differences in their intensity. Cluster analysis of the RAPD-PCR results based on genetic similarity showed genetic difference between E. coli cells treated with AgClNPs@SBA-15/IL nanoparticles, and control and phylogenetic tree were divided to two clusters. Plasmid copy number analysis indicated that after 8 h incubation of E. coli cells with 50, 75, and 100 mu g/ml AgClNPs@SBA-15/IL nanoparticles, copy number of pET21a (+) significantly decreased compared with control which indicating DNA replication inhibition by Ag nanoparticles. In conclusion, the results of this study indicated that AgClNPs@SBA-15/IL nanoparticles can be used as an effective bactericidal agent against bacterial cells.