Antimicrobial activity and biofilm inactivation via non-thermal biocompatible soft plasma jet and micro-dielectric barrier discharge

Biofilm-associated microorganisms such as Escherichia coli , Staphylococcus aureus , and Candida albicans pose serious challenges to food safety and hygiene due to their high resistance to conventional antimicrobial treatments. This study evaluated the antibiofilm and antimicrobial efficacy of a soft plasma jet (SPJ), a non-thermal biocompatible plasma source using air as the working gas. Biofilm biomass, cell viability, and morphological changes were analyzed using crystal violet staining, MTT assay, and scanning electron microscopy (SEM). SPJ treatment significantly reduced biofilm biomass by 69.0% for E. coli , 80.0% for S. aureus , and 67.5% for C. albicans after 8 min, with corresponding viability reductions to 28.0%, 18.4%, and 39.9%, respectively. Scanning electron microscopy results revealed cell deformation and biofilm disruption. The treatment also increased reactive oxygen and nitrogen species (RONS) while lowering pH from 6.6 to 3.1 and enhancing oxidation-reduction potential. These findings demonstrate that SPJ plasma induces strong oxidative stress and physicochemical changes that effectively reduce biofilm biomass and microbial viability, highlighting its potential as a non-thermal disinfection strategy. • Non-thermal plasma effectively inactivates Candida albicans and biofilms • Direct plasma treatment shows higher efficacy than indirect exposure methods • Plasma disrupts biofilms via ROS/RNS, reducing viability and enzyme activity • SEM confirms structural damage and reduced aggregation in plasma-treated cells