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Keywords:

  • Acholeplasma laidlawii ;
  • antioxidant butylated hydroxytoluene;
  • Mycoplasma hominis ;
  • nonthermal argon plasma;
  • reactive oxygen species;
  • transmission electron microscopy;
  • ultraviolet radiation

Abstract

Aim

To study the effects exerted by argon microwave nonthermal plasma (NTP) on cell wall-lacking Mollicutes bacteria.

Methods and Results

108 CFU ml−1 agar plated Mycoplasma hominis and Acholeplasma laidlawii were treated with the nonthermal microwave argon plasma for 30–300 s. The maximal 10- and 100-fold drop was observed for A. laidlawii and Myc. hominis, respectively. Similarly treated Escherichia coli and Staphylococcus aureus demonstrated the 105 and 103 drop, respectively. Removal of cholesterol affected resistance of A. laidlawii. 10 mmol l−1 antioxidant butylated hydroxytoluene decreased mortality by a factor of 25–200. UV radiation alone caused 25–85% mortality in comparison with the whole NTP. Exogenously added hydrogen peroxide H2O2 did not cause mortality. NTP treatment of Myc. hominis triggered growth of microcolonies, which were several tenfold smaller than a typical colony.

Conclusions

Despite the lack of cell wall, A. laidlawii and Myc. hominis were more resistant to argon microwave NTP than other tested bacteria. Mycoplasma hominis formed microcolonies upon NTP treatment. A role of UV and active species was demonstrated.

Significance and Impact of the Study

The first study of NTP effects on Mollicutes revealed importance of a membrane composition for bacterial resistance to NTP. New specific Myc. hominis morphological forms were observed. The study confirmed importance of the concerted action of reactive oxygen species (ROS) with UV and other plasma bioactive agents for NTP bactericidal action.