Cold Atmospheric-Pressure Plasma Caused Protein Damage in Methicillin-Resistant Staphylococcus aureus Cells in Biofilms

Abstract

Biofilms formed by multidrug-resistant bacteria are a major cause of hospital-acquired infections. Cold atmospheric-pressure plasma (CAP) is attractive for sterilization, especially to disrupt biofilms formed by multidrug-resistant bacteria. However, the underlying molecular mechanism is not clear. In this study, CAP effectively reduced the living cells in the biofilms formed by methicillin-resistant Staphylococcus aureus, and 6 min treatment with CAP reduced the S. aureus cells in biofilms by 3.5 log10. The treatment with CAP caused the polymerization of SaFtsZ and SaClpP proteins in the S. aureus cells of the biofilms. In vitro analysis demonstrated that recombinant SaFtsZ lost its self-assembly capability, and recombinant SaClpP lost its peptidase activity after 2 min of treatment with CAP. Mass spectrometry showed oxidative modifications of a cluster of peaks differing by 16 Da, 31 Da, 32 Da, 47 Da, 48 Da, 62 Da, and 78 Da, induced by reactive species of CAP. It is speculated that the oxidative damage to proteins in S. aureus cells was induced by CAP, which contributed to the reduction of biofilms. This study elucidates the biological effect of CAP on the proteins in bacterial cells of biofilms and provides a basis for the application of CAP in the disinfection of biofilms.

Low-Temperature Gas Plasma Combined with Antibiotics for the Reduction of Methicillin-Resistant Staphylococcus aureus Biofilm Both In Vitro and In Vivo

“…Because of the non-selectivity of reactive oxygen species and reactive nitrogen species, they highly react with biological macromolecules—DNA and proteins—and cause damage. The ROS of LTGP inevitably induced DNA damage, such as double-strand break and DNA-protein crosslinking [ 9 , 35 , 36 ]. Quinolone antibiotics, ciprofloxacin and norfloxacin, impede DNA replication, which is also blocked by DNA damage [ 37 ].…”

“…The biofilms were cultured as described previously [ 9 , 29 ]. S. aureus ATCC33591, a methicillin-resistant strain, was purchased from the American Type Culture Collection (ATCC).…”

“…The LTGP device was similar to that used in previous studies [ 9 , 29 ]. As shown in Figure 1 , the surface discharge structure of the LTGP consisted of a high-voltage plane electrode, a liquid-facing grounded mesh electrode with a hexagonal shape, and a dielectric layer (made of polytetrafluoroethylene) sandwiched between the two electrodes.…”

“…Staphylococcus aureus especially methicillin-resistant S. aureus (MRSA), is one of the most frequent causes of skin infections [ 3 , 4 , 5 , 6 , 7 ]. S. aureus cells generally form biofilms on infected skin tissues and are not easily eradicated [ 8 , 9 ]. Biofilms formed by aggregated microbial cells are surrounded by a self-produced extracellular polymeric matrix made of proteins, DNA, and polysaccharides, and adhere to a surface, such as the surfaces of living tissues [ 10 , 11 ].…”

Effects of Atmospheric Plasma Corona Discharge on Agrobacterium tumefaciens Survival

“…These molecules play a significant role in the plasma biocidal process by altering the cell-wall components, the functions and structure of the phospholipid bilayer, the structure of nucleic acids and cellular proteins, gene expressions, and protein synthesis [26,29,30]. It was shown that cold plasma reduced the colony-forming unit (CFU) in Staphylococcus aureus biofilms within 6 min [31]. Inoculated Gram-positive Bacillus subtilis on black peppercorn surfaces were reduced by five orders of magnitude within 300 s, while the Gram-negative Salmonella enteritidis were totally eradicated by seven orders of magnitude [32].…”