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Stochasticity Open Seminar April 19, 2017, 12:00

Open Seminars of the Research Group on


Stochasticity and Control in the Dynamics and Diversity of Immune Repertories: an Example of Multi-Cellular Co-Operation


Wednesday, April 19, 2017, 12:00

at the Israel Institute for Advanced Studies, Room 128



From boom to bust - the dynamics of bacterial adaptation under prolonged resource exhaustion


Ruti Hershberg (Technion)


Many bacteria, including the model bacterium Escherichia coli can survive for years within spent media, following resource exhaustion. We carried out evolutionary experiments, followed by full genome sequencing of hundreds of evolved clones to study the dynamics by which E. coli adapts during the first four months of survival under resource exhaustion. Our results reveal that bacteria evolving under resource exhaustion are subject to intense selection, manifesting in rapid mutation accumulation, enrichment in functional mutation categories and extremely convergent adaptation. Our results further demonstrate that such adaptation is not limited by mutational input. Indeed, mutational input appears to be high enough to enable bacteria to rapidly adapt, in a highly convergent manner and with great temporal precision through fluctuations in allele frequencies. Finally, we demonstrate that due to antagonistic pleiotropy and mutation accumulation, survival under resource exhaustion can severely reduce a bacterium’s ability to grow exponentially, once resources are again available. Combined, our results shed light on bacterial adaptation to long-periods of resource exhaustion and on the consequences such adaptation has on the genetic makeup of individual bacteria and on patterns of genetic variation within bacterial populations.  



Related Research Questions


General question:

  1. How do bacteria adapt to survive under prolonged resource exhaustion and with what consequences on individual bacteria and on the entire bacterial population?


Specific questions:

  1. To what extent does survival under resource exhaustion require genetic adaptation?
  2. Is adaptation under resource exhaustion limited by mutation input?
  3. Does adaptation to resource exhaustion incur a cost on later growth, when resources are again available? 



Suggested Reading


Rapid genetic adaptation during the first four months of survival under resource exhaustion. 
Sarit Avrani, Evgeni Bolotin, Sophia Katz and Ruth Hershberg, (in press 2017).



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