A.A. Chaudhari, S.R. Singh, S. Pillai
Alabama State University,
Keywords: silver coated carbon nanotubes, mechanism, metabolic, gene, protein
Summary:Antibiotic resistance acquired by food borne pathogens such as E. coli has become a global concern. Recently, nanoparticles have been shown to be effective alternatives to antibiotics. Specifically, silver coated carbon nanotubes (AgCNTs) have been shown to possess strong antibacterial activity against several multi-drug resistant pathogens. It is however, critical to reveal the exact molecular mechanism underlying their antibacterial activity. In the present study, we investigated the effect of AgCNTs on metabolically important gene expression and outer membrane proteins of Escherichia coli. Bacterial were treated with 10 µg/ml of AgCNT for 16 h and qRT-PCR was performed to investigate the expression of genes associated with amino acid biosynthesis (argC, metL, metR), DNA binding transcriptional activators (csgD and rstA), DNA repair (mfd, recN, ycaJ), nucleic acid metabolism (carB, purM, nrdF) and TCA cycle (aceF, frdB). Also, the outer membrane proteins (OMPs) were extracted and the samples were run using Experion Pro260 gel. Our results showed that metabolically essential gene expression was significantly upregulated several folds (~4-5 folds) in AgCNTs-treated E. coli compared to untreated bacteria. Also, the OMP pattern in AgCNTs-treated bacteria showed that OMPs were either missing or downregulated in treated bacteria compared to non-treated bacteria. Our results thus indicate that antibacterial activity of AgCNTs may be attributed to their ability to damage the outer membrane protein structure of bacteria,while qRTPCR results indicate that the antibacterial effect is characterized by damage to DNA and nucleic acid metabolism of bacteria.