title: Metabolic changes associated with adaptive diversification in Escherichia coli.
abstract: During a 1000-generation evolution experiment, two types of morphologically and kinetically distinct bacteria repeatedly diverged from a common ancestor in a fully sympatric seasonal environment containing glucose and acetate. To investigate the metabolic modifications associated with this adaptive diversification, we compared transcription profiles of the two derived types and the common ancestor. Both derived types share a suite of common metabolic changes that may represent adaptation to the environment preceding the diversification event. These include improved translation efficiency, glucose uptake capacity via the mal/lamB genes, upregulation of various transporters during stationary phase, and likely the disruption of the rbs operon. The diversification event is associated with the overexpression of genes involved in the TCA cycle, glyoxylate shunt, acetate consumption, and anaerobic respiration in one type and in acetate excretion in the other. These results reveal that competition for both carbon and oxygen have likely played an important role in the adaptation of Escherichia coli during this adaptive diversification event, where one derived type mainly consumes glucose at a fast rate when oxygen is not limiting, and the other derived type consumes glucose and acetate at a slower rate, even when oxygen is limiting.
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. legac@zoology.ubc.ca
authors.forename: Mickaël
authors.initials: M
authors.lastname: Le Gac
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Brazas
authors.forename: Melanie
authors.initials: M
authors.lastname: Bertrand
authors.forename: Jabus G
authors.initials: JG
authors.lastname: Tyerman
authors.forename: Christine C
authors.initials: CC
authors.lastname: Spencer
authors.forename: Robert E W
authors.initials: RE
authors.lastname: Hancock
authors.forename: Michael
authors.initials: M
authors.lastname: Doebeli
mesh_terms: D000220:Adaptation, Biological; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D014644:Genetic Variation; D020411:Oligonucleotide Array Sequence Analysis; D014158:Transcription, Genetic
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial