Evolution of gene expression in one population of the Long-Term Evolution Experiment with Escherichia coli

We used microarrays to study the changes in whole-genome expression profiles accompanying the evolution of one bacterial population propagated in glucose minimal medium for 20,000 generations. We sampled two clones from the Ara-1 population of the E. coli Long-Term Evolution Experiment at generations 2,000 (REL1164A) and 20,000 (REL8593A). These 2 clones as well as the ancestral strain (REL606) were grown until mid-exponential phase in the same glucose-limited minimal medium and conditions used in the evolution experiment. Total RNAs were extracted from cell pellets and whole genome expression profiles were obtained by using Affymetrix arrays, with 6 biological replicates for each strain.