title: Evolution of E. coli on [U-13C]Glucose Reveals a Negligible Isotopic Influence on Metabolism and Physiology.
abstract: 13C-Metabolic flux analysis (13C-MFA) traditionally assumes that kinetic isotope effects from isotopically labeled compounds do not appreciably alter cellular growth or metabolism, despite indications that some biochemical reactions can be non-negligibly impacted. Here, populations of Escherichia coli were adaptively evolved for ~1000 generations on uniformly labeled 13C-glucose, a commonly used isotope for 13C-MFA. Phenotypic characterization of these evolved strains revealed ~40% increases in growth rate, with no significant difference in fitness when grown on either labeled (13C) or unlabeled (12C) glucose. The evolved strains displayed decreased biomass yields, increased glucose and oxygen uptake, and increased acetate production, mimicking what is observed after adaptive evolution on unlabeled glucose. Furthermore, full genome re-sequencing revealed that the key genetic changes underlying these phenotypic alterations were essentially the same as those acquired during adaptive evolution on unlabeled glucose. Additionally, glucose competition experiments demonstrated that the wild-type exhibits no isotopic preference for unlabeled glucose, and the evolved strains have no preference for labeled glucose. Overall, the results of this study indicate that there are no significant differences between 12C and 13C-glucose as a carbon source for E. coli growth.
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, United States of America.
authors.forename: Troy E
authors.initials: TE
authors.lastname: Sandberg
authors.affiliation: Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE, 19716, United States of America.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Long
authors.affiliation: Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE, 19716, United States of America.
authors.forename: Jacqueline E
authors.initials: JE
authors.lastname: Gonzalez
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, United States of America.|Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Lyngby, Denmark.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Feist
authors.affiliation: Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE, 19716, United States of America.
authors.forename: Maciek R
authors.initials: MR
authors.lastname: Antoniewicz
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, United States of America.|Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Lyngby, Denmark.
authors.forename: Bernhard O
authors.initials: BO
authors.lastname: Palsson
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics; D002250:Carbon Radioisotopes / Q000633:toxicity*; D004269:DNA, Bacterial / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D019143:Evolution, Molecular; D016680:Genome, Bacterial; D005947:Glucose / Q000378:metabolism*; D064688:Metabolic Flux Analysis; D017422:Sequence Analysis, DNA
chemical_list: D002250:Carbon Radioisotopes; D004269:DNA, Bacterial; D005947:Glucose