Modeling the inactivation of Bacillus subtilis spores during cold plasma sterilization

ABSTRACT The lethal and sublethal effect of a dielectric barrier discharge atmospheric cold plasma on Staphylococcus aureus were investigated by nonselective and selective media. The inactivation level and sublethally injured proportions of S. aureus cells by dielectric barrier discharge atmospheric cold plasma depended on the treatment times (0, 5, 15, and 45 s), applied input powers (40, 50, and 60 W), and gap distances (2, 4, and 6 mm). Under weak conditions (e.g., 5 s, 40 W, and 6 mm), the occurrence of inactivation and sublethal injury of S. aureus showed a relatively low level. Strong treatment (e.g., 45 s, 60 W, and 2 mm) resulted in highly an inactivated rate, but with small fractions of sublethally injured S. aureus cells. Mild action of cold plasma induced both a large inactivation and a sublethal injury of S. aureus. Therefore, it is significant to optimize the processing of cold plasma sterilization in practice to ensure food safety.

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Design of a Switching Flyback Transformer as High Voltage and Frequency Power Supply for Raw Milk Cold Plasma Sterilization

International Journal of Science, Technology & Management ◽

10.46729/ijstm.v1i3.50 ◽

2020 ◽

Vol 1 (3) ◽

pp. 230-236

Author(s):

Muhamad Ibnu Fajar ◽

Elfahra Casanza Amalda ◽

Muhammad Ali Akram Syah ◽

Nurussa’adah

Keyword(s):

Thermal Plasma ◽

Thermal Equilibrium ◽

Cold Plasma ◽

Raw Milk ◽

Milk Quality ◽

Positive Electrode ◽

Fast Method ◽

Temperature Plasma ◽

Plasma Sterilization ◽

Non Thermal Plasma

Plasma is one of the four fundamentals states of matter other than solid, liquid and gas. In terms of temperature, plasma can be classified into Hot Plasma occurs in thermal equilibrium, Thermal Plasma occurs in non-thermal equilibrium, Cold Plasma occurs in non-thermal equilibrium Cold plasma is an ultra-fast method of sterilization that operates under ambient temperatures (ideal for thermolabile products) at a low running cost and is environment-friendly. Therefore, technology is needed to solve the problem through the innovation of a milk sterilization machine with the principle of non-thermal plasma sterilization by utilizing plasma technology to reduce microbial contamination. The output frequency and voltage are determined through software simulation using voltmeter, oscilloscope, and counter timer. After 220VAC supplies a voltage step down and rectifier circuit to produce a 12VDC output voltage to supply the Switching circuit voltage and the Flyback Transformer driver. Rated voltage and frequency reach 20kV 15kHz.The positive wire from the Flyback Transformer is connected to the acrylic box filled with water (positive electrode) and the ground wire is connected to another acrylic sheet (ground electrode. The milk medium to be sterilized can be placed on the positive electrode or between the ground and positive electrodes. Non-thermal plasma has an effective ability to decontaminate bacteria. This is because plasma is composed of a mixture of ionized particles, reactive radical molecules, and also ultraviolet Schematic circuit design has been successfully simulated. Acrylic sterilization media designs can be used to generate plasma. The mechanism of bacterial sterilization in milk is by the activity of inhibiting bacterial biofilms which can lead to bacterial DNA damage through reactive species in the non-thermal plasma used. Milk quality testing is carried out based on comparison of supporting literature with milk quality requirements according to SNI 3950: 2014.

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Use of Antibody to aid Visualization of Protein at the Termini of Bacteriophage Ø29 DNA

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600002385 ◽

1980 ◽

Vol 38 ◽

pp. 540-541

Author(s):

Dwight Anderson ◽

Charlene Peterson ◽

Gursaran Notani ◽

Bernard Reilly

Keyword(s):

Electron Microscopy ◽

Bacillus Subtilis ◽

Dna Synthesis ◽

Restriction Endonuclease ◽

Protein Complex ◽

Protein Product ◽

Viral Dna ◽

Small Proteins ◽

Antibody Labeling ◽

Subtilis Bacteriophage

The protein product of cistron 3 of Bacillus subtilis bacteriophage Ø29 is essential for viral DNA synthesis and is covalently bound to the 5’-termini of the Ø29 DNA. When the DNA-protein complex is cleaved with a restriction endonuclease, the protein is bound to the two terminal fragments. The 28,000 dalton protein can be visualized by electron microscopy as a small dot and often is seen only when two ends are in apposition as in multimers or in glutaraldehyde-fixed aggregates. We sought to improve the visibility of these small proteins by use of antibody labeling.

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