Friday, April 19, 2019 - 12:30 to 13:30
MSI Small Lecture Theatre
Professor Nicola Stanley-Wall
Dr Megan Bergkessel
California Institute of Technology, Pasadena
Bacteria in natural environments spanning the clinic to the soil spend very little time dividing exponentially at their maximum rates before they have depleted the locally available nutrients. That a single E. coli cell dividing at its maximum laboratory growth rate would yield a colony larger than the volume of the known universe in less than 3 days’ time powerfully illustrates this idea. Instead, most bacteria spend most of their time in dormant or slow-growing states, where cell division and cell death are roughly in balance to maintain population sizes. Mounting evidence suggests that bacteria in dormant states are intrinsically tolerant to antibiotics, and the ability of opportunistic pathogens to maintain ubiquitous reservoirs of organisms in many low-nutrient environments can contribute to the spread of genetic determinants of antibiotic resistance. Because most of our knowledge of transcription, translation, and DNA replication comes from studies in a handful of model organisms doubling rapidly under nutrient-replete conditions, understanding how bacterial cells regulate their activities under conditions of no net population growth represents an important frontier area for microbiology. We have begun to explore this topic using the opportunistic pathogen Pseudomonas aeruginosa as a model organism, and our findings have important implications for human health. We have identified a novel transcriptional regulator specific to slow-growing states, and we are continuing to work towards understanding how this and other regulators contribute to survival in the “real world” that bacteria face.
Megan Bergkessel is a post-doctoral fellow in the laboratory of Dianne Newman at Caltech in Pasadena, California, where she has been studying regulation of slow growth in Pseudomonas aeruginosa with support from the North American Cystic Fibrosis Foundation. She completed her Ph.D. in the laboratory of Christine Guthrie at the University of California, San Francisco, studying the regulation of ribosome biogenesis in baker’s yeast. These experiences reflect her long-standing interest in utilizing diverse approaches to understand how microbes fine-tune their growth in the face of environmental challenges.