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Nitrate Capture Investigation in Plasma-Activated Water and Its Antifungal Effect on Cryptococcus pseudolongus Cells
Geon Joon Lee1, Pradeep Lamichhane1, Seong Jae Ahn2
1Department of Electrical and Biological Physics, Plasma Bioscience Research Center, Kwangwoon University, Seoul 01897, Korea.
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.
Insights
Magnesium ions capture nitrate in plasma-activated water (PAW), reducing its antifungal effect on the fungus Cryptococcus pseudolongus. This nitrate capture allows for controlled manipulation of PAW
Area of Science:
- Plasma physics and chemistry
- Mycology
- Water treatment technologies
Background:
- Plasma-activated water (PAW) is explored for its potential applications, including antimicrobial effects.
- Fungal pathogens like Cryptococcus pseudolongus pose challenges due to their rigid cell walls.
- Nitrate ions are identified as key reactive species in PAW with antifungal properties.
Purpose of the Study:
- To investigate the role of magnesium ions in capturing nitrate within PAW.
- To evaluate the impact of magnesium-mediated nitrate capture on the antifungal efficacy of PAW against Cryptococcus pseudolongus.
- To understand how manipulating nitrate concentration affects PAW's antifungal activity.
Main Methods:
- Plasma-activated water (PAW) was generated by injecting plasma into deionized water (DW).
- Plasma-activated magnesium water (PA-Mg-W) was created by immersing a magnesium block during plasma treatment.
- Optical emission, absorption, and Raman spectroscopy were used to analyze plasma species and nitrate concentration.
- Antifungal activity was assessed by measuring the cell viability of Cryptococcus pseudolongus exposed to PAW and PA-Mg-W.
Main Results:
- Plasma treatment generated reactive oxygen and nitrogen species, with nitrate ions identified as dominant reactive species in both PAW and PA-Mg-W.
- PA-Mg-W exhibited a neutralized pH compared to acidic PAW due to magnesium's interaction with hydrogen ions.
- Magnesium ions reduced free nitrate content in PA-Mg-W by forming nitrate salts.
- While both PAW and PA-Mg-W showed antifungal effects, PA-Mg-W resulted in higher Cryptococcus pseudolongus cell viability, indicating reduced antifungal efficacy.
- Nitrate concentration was found to have a dose-dependent antifungal effect.
Conclusions:
- Magnesium ions effectively capture nitrate in PAW, thereby modulating its antifungal properties.
- The antifungal efficacy of PAW against Cryptococcus pseudolongus can be controlled by manipulating nitrate levels through magnesium ion interaction.
- This study highlights a method for fine-tuning the application of plasma-activated water for specific biological targets by managing key reactive species.
