Transcriptome analysis of Bacillus subtilis in response to physical plasma treatment

In this study, we introduce for the first time a growth chamber system suitable for physical plasma treatment of bacteria in liquid medium. Bacillus subtilis 168 cells were treated with argon plasma in order to investigate their specific stress response usong a proteomic and transcriptomic approach. The treatment with three different discharge voltages revealed not only growth differences, but also clear cellular stress responses. B. subtilis faces severe cell wall stress, which was made visible alsoelectron microscopy, DNA damages and oxidative stress. The biological findings could be supported by the reactive plasma species, found by plasma diagnostics, i.e. optical emission spectroscopy (OES) and Fourier transformed infrared spectroscopy (FTIR). Cells were grown in LB medium. At OD540 of 0.5, argon plasma treatment was set for 15 min with a discharge power of 5 W. Samples for mircroarray analysis were taken 5 min after the 15 min plasma treatment. Microarray hybridizations were performed with RNA from three biological replicates. The individual samples were labeled with Cy5; a reference pool containing equal amounts of RNA from all samples was labeled with Cy3.