ИСТИНА

Bacteria of the Mollicutes class are the smallest free-living organisms. Some Mollicutes species are human, animal and plant pathogens, which inhabit the surface of eukaryotic cells. The intrinsic feature of the Mollicutes is lack of the peptidoglycan-containing cell wall typical for other bacteria. Membranes of the Mollicutes have a composition similar to the composition of eukaryotic membranes [1]. To establish the effectiveness of the non-thermal plasma (NTP) against Mollicutes, we applied it to Mycoplasma hominis and Acholeplasma laidlawii, which are among the most widely spread Mollicutes. The previously described MicroPlaSter β source of the microwave argon plasma [2] was used to treat nutritive agar plated M. hominis and A. laidlawii for 30-300 s. Dependence of bacterial resistance on the medium composition was studied. Input of UV and ROS was evaluated. A dose-dependent bactericidal effect on tested species was shown. Still, the effect was less pronounced than for other bacterial species tested under similar conditions. So, the maximal 10- and 100-fold drop was observed for A. laidlawii and M. hominis, respectively. Similarly treated E. coli and S. aureus demonstrated the 10 5 and10 3 drop, respectively. Cholesterol presented in the cultivation medium affected resistance of A. laidlawii. Addition of 10 mM antioxidant butylated hydroxytoluene decreased mortality by a factor of 25-200. Exogenously added hydrogen peroxide H 2 O 2 did not cause mortality. UV radiation alone caused 25-85 % mortality in comparison with the whole NTP. NTP treatment of M. hominis triggered growth of microcolonies, which were several tens fold smaller than a typical colony. A mean diameter of cells from microcolonies was 98 ± 6 nm while the diameter of control M. hominis cells ranged from 206 to 1320 nm (the mean was 689 ± 319 nm; p<0,005). Obtained results indicated a high degree of heterogeneity and adaptation of Mollicutes. Despite a lack of the cell wall, A. laidlawii and M. hominis were more resistant to argon microwave NTP than other tested bacteria. The membrane composition seemed to be important for the increased resistance to NTP. References [1] Razin, S., Yogev, D. and Naot, Y. Microbiol Mol Biol Rev 62, 1094-1156 (1998). [2] Shimizu, T., Steffes, B., Pompl, R., Jamitzky, F., Bunk, W. , Ramrath, K., Georgi, M., Stolz, W., Schmidt, H., Urayama, T., Fujii, S. and Morfill, G.E. Plasma Processes and Polymers 5, 577-582 (2008).