Bacteria have a remarkable capacity to thrive in adverse environments. Their adaptability relies on stress responses that provide temporary protection, for example by repairing cell damage or removing toxic chemicals. Such phenotypic adaptation offers cells a window of opportunity to evolve permanent stress resistance through genetic change. Failures to cure bacterial infections with antibiotics are often due to stress responses that promote bacterial survival as well as the evolution of drug resistance.
Our lab seeks to understand how this works at the molecular level using a quantitative interdisciplinary approach. We focus on the mechanisms of DNA repair and mutagenesis, which are essential both for stress survival and for genetic change. A key aspect of our research is developing fluorescence microscopy techniques to visualise molecular events in real-time within living cells. We use super-resolution microscopy and single-molecule tracking to record the localization and movement of individual molecules such as DNA repair enzymes or transcription factors. To monitor the cellular responses to stress, we use microfluidic devices for imaging single cells. This allows us to decipher how molecular events inside cells determine long-term cell fates.
Curiously, single-cell analysis revealed that bacterial phenotypes are variable even in a constant environment, a phenomenon that may be linked to stress survival. We discovered that mutation rates are also variable due to fluctuations in the expression of DNA repair proteins. These findings open fundamental questions about the mechanisms and regulation of mutagenesis, which we are now addressing using a range of novel microscopy and genetic approaches.