TY - JOUR
T1 - In vitro antimicrobial effects and mechanism of atmospheric-pressure He/O2 plasma jet on Staphylococcus aureus biofilm
AU - Xu, Zimu
AU - Shen, Jie
AU - Cheng, Cheng
AU - Hu, Shuheng
AU - Lan, Yan
AU - Chu, Paul K.
PY - 2017/2/9
Y1 - 2017/2/9
N2 - The antimicrobial effects and associated mechanism of inactivation of Staphylococcus aureus (S. aureus) NCTC-8325 biofilms induced by a He/O2 atmospheric-pressure plasma jet (APPJ) are investigated in vitro. According to CFU (colony forming units) counting and the resazurin-based assay, the 10 min He/O2 (0.5%) APPJ treatment produces the optimal inactivation efficacy (>5 log10 ml-1) against the S. aureus biofilm and 5% of the bacteria enter a viable but non-culturable (VBNC) state. Meanwhile, 94% of the bacteria suffer from membrane damage according to SYTO 9/PI counterstaining. Scanning electron microscopy (SEM) reveals that plasma exposure erodes the extracellular polymeric substances (EPS) and then the cellular structure. The H2DCFDA-stained biofilms show larger concentrations of intracellular reactive oxygen species (ROS) in membrane-intact bacteria with increasing plasma dose. The admixture of oxygen in the working gas highly contributes to the deactivation efficacy of the APPJ against S. aureus and the plasma-induced endogenous ROS may work together with the discharge-generated ROS to continuously damage the bacterial membrane structure leading to deactivation of the biofilm microbes.
AB - The antimicrobial effects and associated mechanism of inactivation of Staphylococcus aureus (S. aureus) NCTC-8325 biofilms induced by a He/O2 atmospheric-pressure plasma jet (APPJ) are investigated in vitro. According to CFU (colony forming units) counting and the resazurin-based assay, the 10 min He/O2 (0.5%) APPJ treatment produces the optimal inactivation efficacy (>5 log10 ml-1) against the S. aureus biofilm and 5% of the bacteria enter a viable but non-culturable (VBNC) state. Meanwhile, 94% of the bacteria suffer from membrane damage according to SYTO 9/PI counterstaining. Scanning electron microscopy (SEM) reveals that plasma exposure erodes the extracellular polymeric substances (EPS) and then the cellular structure. The H2DCFDA-stained biofilms show larger concentrations of intracellular reactive oxygen species (ROS) in membrane-intact bacteria with increasing plasma dose. The admixture of oxygen in the working gas highly contributes to the deactivation efficacy of the APPJ against S. aureus and the plasma-induced endogenous ROS may work together with the discharge-generated ROS to continuously damage the bacterial membrane structure leading to deactivation of the biofilm microbes.
KW - atmospheric-pressure plasma jet (APPJ)
KW - biofilm inactivation
KW - reactive oxygen species (ROS)
KW - Staphylococcus aureus
UR - http://www.scopus.com/inward/record.url?scp=85014341887&partnerID=8YFLogxK
UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-85014341887&origin=recordpage
U2 - 10.1088/1361-6463/aa593f
DO - 10.1088/1361-6463/aa593f
M3 - RGC 21 - Publication in refereed journal
SN - 0022-3727
VL - 50
JO - Journal of Physics D: Applied Physics
JF - Journal of Physics D: Applied Physics
IS - 10
M1 - 105201
ER -