Inactivation pathways of Escherichia coli and Staphylococcus aureus induced by transient spark discharge in liquids

Cold plasma finds considerable interest in biodecontamination. A major issue is to elucidate the pathways of plasma–bacteria interaction. The present work aims at studying inactivation mechanisms for planktonic bacteria Escherichia coli and Staphylococcus aureus induced by cold plasma generated by a transient spark discharge. Changes in bacterial viability, metabolic activity, membrane integrity, intracellular reactive oxygen species level, and cell morphology reveal different patterns of cellular damage of the bacteria. Our results emphasize the importance of cell membrane integrity and maintenance of intracellular redox balatnce to resist plasma treatment. The physicochemical properties of the plasma‐treated liquid (PTL) are monitored. Acidification and accumulation of various reactive species including •OH, H2O2, ONOOH, and NO3− in PTL play crucial roles in bacterial inactivation. This study focuses on the investigation of plasma‐induced effects on Gram‐negative and Gram‐positive bacteria in both exponential and stationary growth phases. Bacterial viability, metabolic activity, membrane integrity, intracellular reactive oxygen, and cell morphology are confronted with the composition of plasma‐treated liquid to understand bacterial inactivation mechanisms.