Chemical mutagenesis of Listeria monocytogenes for increased tolerance to benzalkonium chloride shows independent genetic underpinnings and off-target antibiotic resistance

作者：Tyler Bechtel, Julia Hershelman, Mrinalini Ghoshal, Lynne McLandsborough, John G. Gibbons · 发表于：PLoS ONE · 年份：2024 · DOI：10.1371/journal.pone.0305663 · 被引用次数：11 · 研究领域：Listeria monocytogenes in Food Safety、Pharmaceutical and Antibiotic Environmental Impacts、Antimicrobial agents and applications

Listeria monocytogenes, a potentially fatal foodborne pathogen commonly found in food processing facilities, creates a significant economic burden that totals more than $2 billion annually in the United States due to outbreaks. Quaternary ammonium compounds (QACs), including benzalkonium chloride (BAC), are among the most widely used sanitizers to inhibit the growth and spread of L. monocytogenes from food processing facilities. However, resistance to QACs has been increasing in L. monocytogenes and different genetic mechanisms conferring resistance have been discovered. Here, we used ethyl methanesulfonate (EMS) to chemically mutagenize the BAC-susceptible strain, L. monocytogenes FSL-N1-304. We isolated two mutants with increased tolerance to BAC compared to the parental strain. Next, we assessed the off-target effect of increased tolerance to BAC by measuring the minimum inhibitory concentrations (MICs) of a diverse set of antibiotics, revealing that mut-1 and mut-2 displayed significantly increased resistance to fluoroquinolone antibiotics compared to the parental strain. A hemolysis assay was then used to investigate a potential correlation between BAC tolerance and virulence. Interestingly, mut-1 and mut-2 both exhibited significantly higher hemolysis percentage than the parental strain. We then sequenced the genomes of the parental strain and both mutants to identify mutations that may be involved in the increased resistance to BAC. We identified 3 and 29 mutations in ...