Authors: Basit Yousuf Jayesh J Ahire Leon M T Dicks
Publish Date: 2016/02/10
Volume: 100, Issue: 12, Pages: 5569-5580
Abstract
The aim of this study was to compare the antibacterial properties of the surfaces of copper plates that were rolled to a thickness of 25 and 100 μm Differences in topology of 25 and 100μmthick copper plates were studied using scanning electron microscopy SEM atomic force microscopy AFM and Xray diffraction XRD Antibacterial activity of the copper surfaces was tested against strains of Staphylococcus aureus Escherichia coli Klebsiella pneumoniae Pseudomonas aeruginosa Listeria monocytogenes Salmonella typhimurium Streptococcus sp BY1 Enterococcus sp BY2 and Bacillus cereus BY3 Changes in viable cell numbers were determined by plating onto optimal growth media and staining with LIVE/DEAD BacLight™ Changes in metabolic activity were recorded by expression of the luciferase lux gene Cell morphology was studied using SEM Accumulation and diffusion of copper from cells were recorded using inductively coupled plasma mass spectroscopy ICPMS Lipid and protein oxidation were recorded spectrophotometrically Surfaces of 25μmthick copper plates were rough compared to that of 100μmthick copper plates For most species a fivelog reduction in cell numbers cell membrane instability and a decline in metabolic activity were recorded after 15 min of exposure to 25μmthick copper plates Copper accumulated in the cells and lipids and proteins were oxidized The rough surface of thinner copper plates 25 μm thick released more copper and was more antimicrobial compared to thicker 100 μm copper plates Cell death was attributed to destabilization of the cell membrane lipid peroxidation and protein oxidationThe authors would like to thank Rozanne Adams and Lize Engelbrecht for their assistance with flow cytometry and Deon Neveling for assistance with XRD and AFM B Yousuf and JJ Ahire are grateful to Stellenbosch University for postdoctoral fellowships We thank TraceXtec Pty Ltd for funding the research
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