Mechanistic study on the susceptibility of <i>Staphylococcus aureus</i> to common antimicrobial preservatives mediated by wall teichoic acids

<i>Staphylococcus aureus</i> is a disease-causing bacterium frequently detected in raw and packaged food that can be strongly insensitive to many bacteria-inhibiting or bacteria-killing agents. With the widespread use of antimicrobial food preservatives during food processing and packaging, there is a potential risk that these preservatives may force <i>S. aureus</i> to become less sensitive. Given that <i>S. aureus</i> tolerates many antimicrobial agents using mechanisms related to wall teichoic acids (WTAs), the negatively charged polymers that are anchored in the cell wall of this bacterium, it is necessary to evaluate whether <i>S. aureus</i> presents WTA-dependent sensitivity to antimicrobial food preservatives and how WTAs affect <i>S. aureus</i> interaction with these preservatives. Our study answered these questions for tea polyphenol, sodium dehydroacetate, and ε-polylysine and revealed three WTA-related mechanisms including charge repulsion, surface trapping, and decline in cell wall permeability. This work emphasizes the need for further control over food safety.