title: Stationary phase gene expression of Mycobacterium tuberculosis following a progressive nutrient depletion: a model for persistent organisms?
abstract: The majority of individuals infected with TB develop a latent infection, in which organisms survive within the body while evading the host immune system. Such persistent bacilli are capable of surviving several months of combinatorial antibiotic treatment. Evidence suggests that stationary phase bacteria adapt to increase their tolerance to environmental stresses. We have developed a unique in vitro model of dormancy based on the characterization of a single, large volume fermenter culture of M. tuberculosis, as it adapts to stationary phase. Cells are maintained in controlled and defined aerobic conditions (50% dissolved oxygen tension), using probes that measure dissolved oxygen tension, temperature, and pH. Microarray analysis has been used in conjunction with viability and nutrient depletion assays to dissect differential gene expression. Following exponential phase growth the gradual depletion of glucose/glycerol resulted in a small population of survivors that were characterized for periods in excess of 100 days. Bacilli adapting to nutrient depletion displayed characteristics associated with persistence in vivo, including entry into a non-replicative state and the up-regulation of genes involved in beta-oxidation of fatty acids and virulence. A reduced population of non-replicating bacilli went on to adapt sufficiently to re-initiate cellular division.
authors.affiliation: Department of Cellular and Molecular Medicine, St. George's Hospital Medical School, London, UK. pg005315@sghms.ac.uk
authors.forename: Tobias
authors.initials: T
authors.lastname: Hampshire
authors.forename: Shamit
authors.initials: S
authors.lastname: Soneji
authors.forename: Joanna
authors.initials: J
authors.lastname: Bacon
authors.forename: Brian W
authors.initials: BW
authors.lastname: James
authors.forename: Jason
authors.initials: J
authors.lastname: Hinds
authors.forename: Ken
authors.initials: K
authors.lastname: Laing
authors.forename: Richard A
authors.initials: RA
authors.lastname: Stabler
authors.forename: Philip D
authors.initials: PD
authors.lastname: Marsh
authors.forename: Philip D
authors.initials: PD
authors.lastname: Butcher
mesh_terms: D000222:Adaptation, Physiological; D000332:Aerobiosis; D002244:Carbon / Q000378:metabolism; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D005798:Genes, Bacterial / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D066298:In Vitro Techniques; D008954:Models, Biological; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D002244:Carbon; D005947:Glucose; D005990:Glycerol