RNA-Sequencing Analysis of Escherichia coli Suspended in Conductive Water Column Falling into Dielectric Barrier Discharge Gap

This study uniquely applies RNA-sequencing analysis to elucidate the molecular mechanism underlying Escherichia coli (DH10B) inactivation by dielectric barrier discharge (DBD). This provides new insights into the changes in gene expression associated with oxidative stress and membrane damage. A thin water column containing E. coli acts as an electrode, so that DBD occurs at the air gap between the water column and the glass barrier. Relationships between the viability ratio of E. coli and the DBD treatment time are evaluated for three types of conductive solutions, NaCl, (NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>)<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>, and Mg(SO)<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>. The viability ratio of E. coli in the NaCl solution is reduced to 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> by the treatment for 30 min, whereas the ratios in (NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>)<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> and Mg(SO)<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> solutions are not reduced by the treatment for the same time. We extract RNA from DBD-treated E. coli in the NaCl solution and analyze the changes in gene expression. RNA-sequencing analysis shows that the expression levels of genes involved in light stimulation and oxidative stress tend to increase by DBD. On the other hand, those involved in lipid biosynthesis processes tend to decrease. It is concluded that the reason why E. coli can be effectively sterilized in the NaCl solution is that the hypochlorite ions produced by DBD act as important radicals that degrade the cytoplasmic and outer membrane.