Premium
Physical and Microbiological Characterisation of Staphylococcus epidermidis Inactivation by Dielectric Barrier Discharge Plasma
Author(s) -
Helmke Andreas,
Hoffmeister Dennis,
Berge Frank,
Emmert Steffen,
Laspe Petra,
Mertens Nina,
Vioel Wolfgang,
Weltmann KlausDieter
Publication year - 2011
Publication title -
plasma processes and polymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 74
eISSN - 1612-8869
pISSN - 1612-8850
DOI - 10.1002/ppap.201000168
Subject(s) - dielectric barrier discharge , staphylococcus epidermidis , membrane , biophysics , reactive oxygen species , chemistry , bacterial cell structure , scanning electron microscope , plasma , bacteria , cell membrane , microbiology and biotechnology , staphylococcus aureus , materials science , biology , biochemistry , physics , electrode , quantum mechanics , composite material , genetics
The inactivation of the Gram‐positive bacteria Staphylococcus epidermidis (ATCC 12228) in its vegetative state was studied in vitro after exposure to cold atmospheric pressure plasma generated by direct dielectric barrier discharge (DBD). Compared to UV radiation at 254 nm, plasma UV emission yielded no significant contribution to bacterial inactivation. Analysis of bacterial growth inhibition revealed a pH dependency on growth media. Yet, measurements combined with numerical simulations excluded the pH shift induced by plasma generated reactive species as the main cause of bacterial inactivation. Scanning electron microscopy (SEM) images showed no alteration of cell walls, while fluorescence microscopy revealed lethal damage to cell membranes even after 1 s treatment. When the cell membrane was already severely damaged, also degradation of the bacterial DNA by plasma treatment was found. We conclude that membrane damage due to reactive oxygen species (ROS) and DNA degradation are the main mechanisms of plasma‐induced bacterial death that is aggregated by milieu acidification.