Quantitative Analysis of the Inactivation Mechanisms of Escherichia coli by a Newly Developed Method Using Propidium Monoazide

摘要

The present study investigates a newly developed method using propidium monoazide (PMA) to detect damage on the outer membrane of bacteria. In order to verify this method, Escherichia coli were disinfected by ultraviolet, chlorine and sawdust treatments assuming a composting toilet. The inactivation mechanisms were investigated by multiple detection methods focused on which parts and/or functions were damaged. The differences in detection principles among three kinds of growth media and the polymerase chain reaction (PCR) method were used as methods to investigate the damage caused by disinfection. In addition, damage to the outer membrane was distinguished using PMA as pretreatment following PCR or conventional cultivation media, Tryptic Soy Agar (TSA), called PMA-PCR and PMA-TSA, respectively. As a result, it was indicated that chlorination caused outer membrane damage, and that ultraviolet treatment did not. Sawdust treatment at high temperature damaged the outer membranes effectively. It was confirmed that PMA-TSA, a newly developed method, could detect damage on the outer membrane of Escherichia coli more sensitively and quantitatively than PMA-PCR.