## 2 Materials and Experimental Methods
### Soft Plasma Jet Device, Plasma-Activated Water, Plasma Treatments, and Spore Viability  
Figure 1a illustrates an experimental layout of the electric shock-free plasma jet, which consists mainly of a power supply, needle electrode, cylindrical quartz tube, and cylindrical tube electrode.  
Figure 1: (**a**) Experimental layout, photo and schematic diagram of an electric shock-free, atmospheric-pressure air plasma jet, I, Inverter, PNE-GI, Powered needle electrode and Gas input, Q, Cylindrical quartz tube, GE, Grounded electrode, S, Sample, PJ, Plasma jet, (**b**) typical voltage and current profiles of the plasma discharge, and (**c**) optical emission spectrum of the soft plasma jet.  
The quartz tube served as a dielectric barrier between the electrodes to induce an electrical discharge. Plasma radicals were generated by electrodes separated by a dielectric barrier. The outer diameters of the powered needle electrode, cylindrical quartz tube, and cylindrical copper tube were 2.0 mm, 10.0 mm, and 12.0 mm, respectively. A plasma jet threw out through a 1 mm hole to the open air at a flow rate of 1.5 L/min. The plasma plume length was approximately 5 mm. The needle-to-water surface distance was fixed at 10 mm. A tip-to-sample distance was chosen to avoid thermal effects in the plasma-treated sample. In this research, air was used as the plasma working gas for the soft plasma jet. Electric power for the plasma device was supplied by an inverter that converts DC input to 67 kHz AC output. The optical emission spectrum of the plasma jet was measured using a UV-visible spectrometer (Ocean Optics, HR4000, USA). The concentrations of \(H_{2}O_{2}\) and \(NO_{x}\) in the plasma-activated water were measured using QuantiChrom(tm) Peroxide Assay Kit (_DIOX_-250) and QuantiChrom(tm) Nitric Oxide Assay Kit (_DIOX_-100), respectively. The concentration of \(OH\) radical in plasma-activated water was measured using hydroxyl radical-sensitive fluorescence probe, terephthalatic acid (_TA_). As _TA_ molecules bind with hydroxyl radicals, their oxidation product (2-hydroxyterephthalatic acid, _HTA_) becomes fluorescent, allowing hydroxyl radicals to be detected [14]. By comparing the fluorescence spectra of the plasma-treated _TA_- water solution with that of the plasma-untreated _HTA_- water solution, we can obtain the concentration of \(OH\) radical in the plasma-activated water.  
To study the effects of soft plasma jet treatment, the spores were suspended in sterile water at a concentration of \(5\times 10^{7}\) spores/mL. Each well of six-well culture plates (SPL Life Science Co., Pocheon-si, Gyeonggi-do, Korea) received 3 mL of spore suspension. The spore samples were treated by the soft plasma jet. For effective plasma treatment, each well plate was covered by a polystyrene plate with a circular hole of 4 mm diameter, and plasma-induced radicals were delivered to a biological solution through the circular hole of the top plate. To test spore viability, spores with and without soft plasma jet treatment were diluted with sterile water up to 10-fold, spread on SDAY media, and kept at 25 \({}^{\circ}\)C and incubated for 7 days which was enough time to observe visible mycelia fungal colony from survived spores.