Antimicrobial effects of microwave‐induced plasma torch (MiniMIP) treatment on Candida albicans biofilms

Abstract

Summary The susceptibility of Candida albicans biofilms to a non‐thermal plasma treatment has been investigated in terms of growth, survival and cell viability by a series of in vitro experiments. For different time periods, the C. albicans strain SC5314 was treated with a microwave‐induced plasma torch (MiniMIP). The MiniMIP treatment had a strong effect (reduction factor (RF) = 2.97 after 50 s treatment) at a distance of 3 cm between the nozzle and the superior regions of the biofilms. In addition, a viability reduction of 77% after a 20 s plasma treatment and a metabolism reduction of 90% after a 40 s plasma treatment time were observed for C. albicans. After such a treatment, the biofilms revealed an altered morphology of their cells by atomic force microscopy (AFM). Additionally, fluorescence microscopy and confocal laser scanning microscopy (CLSM) analyses of plasma‐treated biofilms showed that an inactivation of cells mainly appeared on the bottom side of the biofilms. Thus, the plasma inactivation of the overgrown surface reveals a new possibility to combat biofilms.

Plasma-treated water affects Listeria monocytogenes vitality and biofilm formation

“…An in uence of the temperature can be excluded (39). Even direct bio lm treatments with the MiniMIP, the previous version of the MidiPLexc, revealed no temperature in uences on the antimicrobial behavior against bio lms (45). Additionally, the temperature increases by approx.…”

“…The colonies for the respective dilution levels were counted manually, and the CFU/ml values were calculated by using the formula: , where 10 x is the dilution factor for the lowest dilution, v is the volume of diluted cell suspension per plate in ml, ∑c y is the total number of colonies on all (n y ) plates of the lowest evaluated dilution level, 10 −x , and ∑c y+1 is the total number of colonies on all (n y+1 ) plates of the next-highest dilution level evaluated, 10 −(x+1) . The calculation is explained in more detail in (45).…”

Characterization of Antimicrobial Effects of Plasma‑Treated Water (PTW) Produced by Microwave‑Induced Plasma (MidiPLexc) on <em>Pseudomonas fluorescens </em>Biofilms

“…The MidiPLexc [30] is a microwave-driven plasma source and an extension of the MiniMIP [29,31]. In contrast to the MiniMIP, this plasma source operates with compressed air instead of argon gas.…”

“…Each dilution step was plated on BHI-agar by pipetting 10 µ l per dilution onto the plate and spread out by using the tilting technique. The plates were incubated at 30 °C for 24 h. The colonies of the respective dilution levels were counted manually, and the CFU/ml were calculated as described before [29].…”

“…The main priority is the complete detachment of the biofilm from the overgrown surface to remove it from the system during the flushing processes. Initial studies have already shown a unique effect of plasma gas on the adhering surface of the biofilm [28,29]. The present study aimed to investigate whether PTW also has such special effects on the biofilm.…”