Quantitative flow cytometry to understand population heterogeneity in response to changes in substrate availability in escherichia coli and saccharomyces cerevisiae chemostats

Research output: Contribution to journalArticle

Abstract

Microbial cells in bioprocesses are usually described with averaged parameters. But in fact, single cells within populations vary greatly in characteristics such as stress resistance, especially in response to carbon source gradients. Our aim was to introduce tools to quantify population heterogeneity in bioprocesses using a combination of reporter strains, flow cytometry, and easily comprehensible parameters. We calculated mean, mode, peak width, and coefficient of variance to describe distribution characteristics and temporal shifts in fluorescence intensity. The skewness and the slope of cumulative distribution function plots illustrated differences in distribution shape. These parameters are person-independent and precise. We demonstrated this by quantifying growth-related population heterogeneity of Saccharomyces cerevisiae and Escherichia coli reporter strains in steady-state of aerobic glucose-limited chemostat cultures at different dilution rates and in response to glucose pulses. Generally, slow-growing cells showed stronger responses to glucose excess than fast-growing cells. Cell robustness, measured as membrane integrity after exposure to freeze-thaw treatment, of fast-growing cells was strongly affected in subpopulations of low membrane robustness. Glucose pulses protected subpopulations of fast-growing but not slower-growing yeast cells against membrane damage. Our parameters could successfully describe population heterogeneity, thereby revealing physiological characteristics that might have been overlooked during traditional averaged analysis.

Details

Authors
  • Anna Lena Heins
  • Ted Johanson
  • Shanshan Han
  • Luisa Lundin
  • Magnus Carlquist
  • Krist V. Gernaey
  • Søren J. Sørensen
  • Anna Eliasson Lantz
Organisations
External organisations
  • Technical University of Denmark
  • Technical University of Munich
  • University of Copenhagen
  • Glycom A/S
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cell Biology

Keywords

  • Flow cytometry, Glucose pulse, Membrane robustness, Population heterogeneity, Quantitative flow cytometry, Reporter strain
Original languageEnglish
Article number187
JournalFrontiers in Bioengineering and Biotechnology
Volume7
Issue numberAUG
Publication statusPublished - 2019
Publication categoryResearch
Peer-reviewedYes