(556e) Optogenetically-Controlled Bacterial Persistence

Bacterial populations produce tolerant persister cells that survive lethal concentrations of antibiotics due to dormancy-related phenotypic changes. Recently, tolerance has been shown to promote the development of antimicrobial resistance based on accumulating genetic mutations. Persister research focuses on linking causality of persister formation to their recalcitrance towards antimicrobial agents. This is challenging, however, due to the low frequency of persisters within a population (typically <1%) and their rapid reversion to normal cells. Several methods have been developed to induce persister formation but require the addition of chemical or biological agents. In this study, we engineered an Escherichia coli strain to control the expression of the toxin gene hipA and thus persistence using blue light. The engineered strain demonstrated 100% persistence with overnight blue light induction, which is more than 30 times higher than the dark control. The blue light-controlled gene expression was validated using a fluorescent reporter strain and real-time quantitative PCR (RT-qPCR) analysis of hipA expression. Using blue light to control persistence provides a new method to study persistence without using chemical agents, which can have impacts on cell metabolism and pathways not related to persistence. Using light also has advantages as a non-invasive tool and reversible induction for studies that require spatial control of bacterial gene expression and persistence.