Selection for Cell Yield Does Not Reduce Overflow Metabolism in Escherichia coli

Iraes Rabbers, Willi Gottstein, Adam M. Feist, Bas Teusink, Frank J. Bruggeman, Herwig Bachmann*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Overflow metabolism is ubiquitous in nature, and it is often considered inefficient because it leads to a relatively low biomass yield per consumed carbon. This metabolic strategy has been described as advantageous because it supports high growth rates during nutrient competition.
Here, we experimentally evolved bacteria without nutrient competition by repeatedly growing and mixing millions of parallel batch cultures of Escherichia coli. Each culture originated from a water-in-oil emulsion droplet seeded with a single cell. Unexpectedly we found that overflow metabolism (acetate production) did not change. Instead, the numerical cell yield during the consumption of the accumulated acetate increased as a consequence of a reduction in cell size. Our experiments and a mathematical model show that fast growth and overflow metabolism, followed by the consumption of the overflow metabolite, can lead to a higher numerical cell yield and therefore a higher fitness compared with full respiration of the substrate. This provides an evolutionary scenario where overflow metabolism can be favorable even in the absence of nutrient competition.
Original languageEnglish
Article numbermsab345
JournalMolecular Biology and Evolution
Volume39
Issue number1
Number of pages10
ISSN0737-4038
DOIs
Publication statusPublished - 2022

Keywords

  • Cell size
  • Emulsion culturing
  • Experimental evolution
  • Metabolic strategy
  • Overflow metabolism
  • r/k selection
  • Yield

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