title: Global gene expression in Escherichia coli K-12 during short-term and long-term adaptation to glucose-limited continuous culture conditions.
abstract: Microarray technology was used to study the cellular events that take place at the transcription level during short-term (physiological) and long-term (genetic) adaptation of the faecal indicator bacterium Escherichia coli K-12 to slow growth under limited nutrient supply. Short-term and long-term adaptation were assessed by comparing the mRNA levels isolated after 40 or 500 h of glucose-limited continuous culture at a dilution rate of 0.3 h(-1) with those from batch culture with glucose excess. A large number of genes encoding periplasmic binding proteins were upregulated, indicating that the cells are prepared for high-affinity uptake of all types of carbon sources during glucose-limited growth in continuous culture. All the genes belonging to the maltose (mal/lamB) and galactose (mgl/gal) operons were upregulated. A similar transcription pattern was observed for long-term cultures except that the expression factors were lower than in the short-term adaptation. The patterns of upregulation were confirmed by real-time RT-PCR. A switch from a fully operational citric acid cycle to the PEP-glyoxylate cycle was clearly observed in cells grown in glucose-limited continuous culture when compared to batch-grown cells and this was confirmed by transcriptome analysis. This transcriptome analysis confirms and extends the observations from previous proteome and catabolome studies in the authors' laboratory.
authors.affiliation: Swiss Federal Institute for Aquatic Science and Technology, PO Box 611, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland.
authors.forename: Alessandro G
authors.initials: AG
authors.lastname: Franchini
authors.affiliation: Swiss Federal Institute for Aquatic Science and Technology, PO Box 611, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Egli
mesh_terms: D000222:Adaptation, Physiological; D004734:Energy Metabolism; D048168:Escherichia coli K12 / Q000235:genetics* / Q000254:growth & development; D005947:Glucose / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D005947:Glucose