Global characterization of physical plasma impact on vegetative microorganisms

Summary form only given. Plasma medicine and also inactivation of bacteria with physical plasmas is a promising new field of life science with huge interest especially for medical applications. Despite numerous successful applications of low temperature gas plasmas in medicine and decontamination, the fundamental nature of the interactions between plasma and microorganisms is to a large extent unknown. A detailed knowledge of these interactions is essential for the development of new as well as for the enhancement of established plasma treatment procedures.In the present work we introduce a growth chamber system suitable for physical plasma treatment of bacteria in liquid medium. The gram positive model organism Bacillus subtilis was treated with plasma, in order to investigate the specific stress response using a proteomic and transcriptomic approach. Two different gas admixtures as well as different discharge voltages were applied during the plasma treatment. We were able to connect reactive agents produced in the plasma with the specific cellular response. This response displayed a clear correlation in dependence of the used gas and the plasma power. B. subtilis faces e.g. different kinds of cell wall stress, depending on the used gas, which was made visible also by electron microscopy. Furthermore, the extent of DNA damages and oxidative stress differed significantly, again, depending on the used gas and plasma power. The biological findings could be supported by the diagnostic of reactive plasma species.