CAREER: Bacterial heterogeneity in stress survival

South Dakota State University, Brookings SD

Investigators

Abstract

Bacterial persisters have an incredible ability to survive stress and are a major cause of recurrent bacterial infections, failures in antibiotic drug therapy, and evolution of antibiotic resistance. Most cells in a bacterial population die when exposed to a major stress, such as antibiotics, but a small fraction of cells survive for a long time. These survivors, also known as persisters, appear to arise as a result of variability in cell behaviors across the population. The goal of this project is to discover the mechanisms that allow the formation, maintenance, and survival of bacterial persisters and thus to help understand key features of bacterial survival. The work will involve student researchers, including those from underrepresented groups, who will participate in synthetic biology research experiences as part of the project's educational objectives. In addition, the project will provide professional development workshops for K-12 science teachers to enhance their ability to integrate synthetic biology modules into their classrooms. The overall goal of this research is to identify the mechanism that enables some bacterial cells to survive after exposure to stress. One hypothesis to be tested is that survival depends on establishment of some type of epigenetically-determined ‘memory’ of stress that results in higher persister numbers after exposure to the stress. To understand the regulatory processes that enable persisters to survive long-term, lethal stress, the project will use a suite of experimental approaches, such as fluorescence microscopy, microfluidics, and a modified Luria–Delbrück fluctuation test, with synthetic biology and quantitative modeling. In addition, transcriptional analysis, single-cell experiments, and high-throughput techniques will be used to quantify epigenetic patterns in bacteria. The research will produce a quantitative framework for understanding the mechanism responsible for the phenotypic heterogeneity thought to serve as an inherent survival strategy of bacteria. This work will impact fundamental knowledge of how bacteria survive sudden lethal stress and how they deal with harsh environmental fluctuations. The results are expected to offer new insights into the fundamental molecular mechanisms of how cells revive from lethal stress. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.