Nitrate Capture Investigation in Plasma-Activated Water and Its Antifungal Effect on Cryptococcus pseudolongus Cells

Abstract

This research investigated the capture of nitrate by magnesium ions in plasma-activated water (PAW) and its antifungal effect on the cell viability of the newly emerged mushroom pathogen Cryptococcus pseudolongus. Optical emission spectra of the plasma jet exhibited several emission bands attributable to plasma-generated reactive oxygen and nitrogen species. The plasma was injected directly into deionized water (DW) with and without an immersed magnesium block. Plasma treatment of DW produced acidic PAW. However, plasma-activated magnesium water (PA-Mg-W) tended to be neutralized due to the reduction in plasma-generated hydrogen ions by electrons released from the zero-valent magnesium. Optical absorption and Raman spectra confirmed that nitrate ions were the dominant reactive species in the PAW and PA-Mg-W. Nitrate had a concentration-dependent antifungal effect on the tested fungal cells. We observed that the free nitrate content could be controlled to be lower in the PA-Mg-W than in the PAW due to the formation of nitrate salts by the magnesium ions. Although both the PAW and PA-Mg-W had antifungal effects on C. pseudolongus, their effectiveness differed, with cell viability higher in the PA-Mg-W than in the PAW. This study demonstrates that the antifungal effect of PAW could be manipulated using nitrate capture. The wide use of plasma therapy for problematic fungus control is challenging because fungi have rigid cell wall structures in different fungal groups.

Influences of Plasma Plume Length on Structural, Optical and Dye Degradation Properties of Citrate-Stabilized Silver Nanoparticles Synthesized by Plasma-Assisted Reduction

“…At the plasma–liquid interface, prolonged plasma exposure causes a dissociation of water molecules by energetic ions from the plasma jet, resulting in radical generation. Weak emission bands in the 330−380 nm range are generated from the second positive system transition of nitrogen molecules ( ) [ 37 , 38 ], which can be ascribed to plasma operation under atmospheric conditions. The emission at 777 nm was attributed to transition of atomic oxygen ( O ) [ 39 ].…”

Advancements in Plasma Agriculture: A Review of Recent Studies

“…The investigation focused on nitrate capture in PAW, and its antifungal effect on Cryptococcus pseudolongus cells was observed in [137]. The study found that enriching PAW with magnesium ions (PAW-Mg 2+ ) resulted in the control of free nitrate through the formation of nitrate salts by magnesium ions.…”

Plasma Bioscience and Medicine Molecular Research

“…PTW has been shown to have antifungal effects on various fungal pathogens, but its effect on the newly emerged mushroom pathogen Cryptococcus pseudolongus is unknown. Lee et al investigated the capture of nitrate by magnesium ions in PTW and its antifungal effect on C. pseudolongus [6]. The plasma jet generated several reactive oxygen and nitrogen species, and plasma treatment of deionized water produced acidic PTW.…”