Bacterial Sterilization Using Non-Thermal Plasma Method Surface Dielectric Barrier Discharge (SDBD): Effect of Treatment Duration on Colony Count, DNA, Protease Enzymes, and Cell Morphology

Abstract

The ability of Escherichia coli to become increasingly resistant to sterilization has resulted in high cases of this bacterial infection. To overcome this problem, a new method is needed. The circuit design uses 2 parallel plates of copper material. The first plate is HV electrode and second plate is ground electrode which is separated by a dielectric layer. Non-thermal plasma with surface dielectric barrier discharge is generated using a 20 VDC voltage source and then transformed into a high voltage source to generate plasma. Distance between plasma source and fixed sample is 3 mm. OES is used to observe reactive species produced in plasma indicated by magnitude of intensity at certain wavelengths. SDBD non-thermal plasma could be used to inactivate bacteria depending on treatment time. The longer treatment time, greater inactivation ability. For the number of colonies after being treated for 120 s, namely 4.33×107 CFU/mL, it was much lower than control, which was 409×107 CFU/ml. For DNA after being treated for 120 s, results of genome from Escherichia coli were no longer visible or faded, marked by a DNA concentration of 8.18 ng/ul, far lower than the control DNA concentration of 124.44 ng/ul. For the activity of the protease enzyme, the time variation of 105 s had the smallest activity value of the protease enzyme, namely 35.375 U/mL compared to control, which was 52.307 U/mL whereas for cell morphology after 120 s treatment showed increasingly severe cell damage observed using SEM. Non-thermal plasma SDBD configurations can be used to inactivate or kill bacteria. Effectiveness or capability of non-thermal plasma also depends on the treatment time. SDBD nonthermal plasma ability increases with the longer treatment time. HIGHLIGHTS In this research, a non-thermal plasma method of surface dielectric barrier discharge (SDBD) for Escherichia coli sterilization was developed. The results of research on inactivation of Escherichia coli bacteria using non-thermal plasma SDBD showed that the configuration of non-thermal plasma SDBD could be used to inactivate or kill bacteria. The effectiveness or capability of non-thermal plasma also depends on the treatment time. SDBD non-thermal plasma capability increases with longer treatment time. GRAPHICAL ABSTRACT