Population diversification in a yeast metabolic program promotes anticipation of environmental shifts

PLoS Biol. 2015 Jan 27;13(1):e1002042. doi: 10.1371/journal.pbio.1002042. eCollection 2015 Jan.


Delineating the strategies by which cells contend with combinatorial changing environments is crucial for understanding cellular regulatory organization. When presented with two carbon sources, microorganisms first consume the carbon substrate that supports the highest growth rate (e.g., glucose) and then switch to the secondary carbon source (e.g., galactose), a paradigm known as the Monod model. Sequential sugar utilization has been attributed to transcriptional repression of the secondary metabolic pathway, followed by activation of this pathway upon depletion of the preferred carbon source. In this work, we demonstrate that although Saccharomyces cerevisiae cells consume glucose before galactose, the galactose regulatory pathway is activated in a fraction of the cell population hours before glucose is fully consumed. This early activation reduces the time required for the population to transition between the two metabolic programs and provides a fitness advantage that might be crucial in competitive environments.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Carbohydrate Metabolism
  • Computer Simulation
  • Energy Metabolism
  • Galactose / physiology
  • Gene Expression Regulation, Fungal
  • Gene-Environment Interaction
  • Genes, Fungal
  • Glucose / physiology
  • Models, Biological
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Transcription, Genetic
  • Transcriptional Activation


  • Saccharomyces cerevisiae Proteins
  • Glucose
  • Galactose