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Author Notes:

Correspondence: Ichiro Matsumura; Email: imatsum@emory.edu

Author Contributions: Conceived and designed the experiments: IM.

Performed the experiments: AW and KF.

Analyzed the data: IM, KF and AB.

Contributed reagents/materials/analysis tools: AB.

Wrote the paper: IM and KF.

Acknowledgments: We thank Prof. Susan Gilbert for teaching IM about the Production Possibilities Frontier model, and others in the Matsumura lab for their helpful suggestions.

Disclosures: The authors have declared that no competing interests exist.


Research Funding:

This work was supported by the National Science Foundation. KF and IM were supported by grant number EF-1104988 (NSF3)

AB, AW and IM were supported by MCB-0951076 (NSF2)

Escherichia coli Deletion Mutants Illuminate Trade-Offs between Growth Rate and Flux through a Foreign Anabolic Pathway


Journal Title:



Volume 9, Number 2


, Pages e88159-e88159

Type of Work:

Article | Final Publisher PDF


Metabolic engineers strive to improve the production yields of microbial fermentations, sometimes by mutating the genomes of production strains. Some mutations are detrimental to the health of the organism, so a quantitative and mechanistic understanding of the trade-offs could inform better designs. We employed the bacterial luciferase operon (luxABCDE), which uses ubiquitous energetic cofactors (NADPH, ATP, FMNH2, acetyl-CoA) from the host cell, as a proxy for a novel anabolic pathway. The strains in the Escherichia coli Keio collection, each of which contains a single deletion of a non-essential gene, represent mutational choices that an engineer might make to optimize fermentation yields. The Keio strains and the parental BW25113 strain were transformed with a luxABCDE expression vector. Each transformant was propagated in defined M9 medium at 37°C for 48 hours; the cell density (optical density at 600 nanometers, OD600) and luminescence were measured every 30 minutes. The trade-offs were visualized by plotting the maximum growth rate and luminescence/OD600 of each transformant across a “production possibility frontier”. Our results show that some loss-of-function mutations enhance growth in vitro or light production, but that improvement in one trait generally comes at the expense of the other.

Copyright information:

© 2014 Falls et al.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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