Study On The Mechanism Of Plasma Ejection From Living Acinetobacter Baumannii Biofilmt

The biofilm structure provides the conditions for bacteria to resist harsh environment,and enables these aggregated bacteria to adapt to and survive and reproduce normally in various environments,which leads to a significant increase in bacterial resistance and infectivity,and ordinary sterilization methods have been unable to meet the requirements at this stage.Ultraviolet(UV)radiation emitted by low-temperature plasma,including various free radicals,charged particles and excited particles,induces the destruction of bacterial lipids,proteins,DNA and so on,leading to the degradation of cell structure.The inactivation mechanism and regeneration ability of drug-resistant Acinetobacter baumannii biofilm by plasma helium jet from atmospheric pressure pulsed power supply were studied.The inactivation effect of bacteria was detected by morphological changes,culturable development ability,metabolic ability,intracellular reactive oxygen species and membrane integrity.At the end of the culture period of Acinetobacter baumannii biofilm,the total number of bacteria in the biofilm reached7.37 +0.16log10CFU/ml.After 30 minutes of plasma treatment,about 99.9% of the bacteria in the biofilm lost their ability to grow.At the same time,the fluorescence staining method showed that about 80% of the bacteria lost their metabolic ability.Some bacteria entered a viable but uncultured state(VBNC).The SYTO 9/PI fluorescence staining method showed that about 38.2% of the biofilm bacteria had lost the integrity of the cell membrane structure.The fluorescence staining method of H2-DCFDA showed that the bacteria in the biofilm treated by plasma had lost the integrity of the cell membrane structure.The concentration of ROS increased.In the study of the regeneration ability of Acinetobacter baumannii after plasma treatment,the maximum total number of bacteria after regeneration is 5.36 +0.2 log10 CFU/ml.Compared with the total number of bacteria in the first generation,about 99.99% of bacteria are inhibited.Compared with the biomass of bacteria in the first generation biofilm,the biomass of bacteria after regeneration decreases to(11 +0.010)%.When plasma treatment lasts 30 minutes.The percentage of metabolic bacteria decreased to52.9%.This shows that atmospheric pressure plasma jet can not only effectively inactivate bacteria in biofilm,but also have long-term inhibition effect on them.