Why is HSO5− so effective against bacteria? Insights into the mechanisms of Escherichia coli disinfection by unactivated peroxymonosulfate

This study examined the antimicrobial efficacy of peroxymonosulfate (PMS) against bacteria, using Escherichia coli as a model organism. Our investigation delineates the complex mechanisms exerted by unactivated PMS. Thus, an initial redox reaction between PMS and the target biomolecules of bacteria generates SO4•− as the pivotal reactive species for bacterial inactivation; to a lesser extent, •OH, 1O2, or O2•− may also participate. Damage generated during oxidation was identified using an array of biochemical techniques. Specifically, redox processes are promoted by PMS and SO4•− targets and disrupt various components of bacterial cells, predominantly causing extracellular damage as well as intracellular lesions. Among these, external events are the key to cell death. Finally, by employing gene knockout mutants, we uncovered the role of specific gene responses in the intracellular damage induced by radical pathways. The findings of this study not only expand the understanding of PMS-mediated bacterial inactivation but also explain the ten-fold higher effectiveness of PMS than that reported for H2O2. Hence, we provide clear evidence that unactivated PMS solutions generate SO4•− in the presence of bacteria, and consequently, should be considered an effective disinfection method.