title: Sporulation in mycobacteria.
abstract: Mycobacteria owe their success as pathogens to their ability to persist for long periods within host cells in asymptomatic, latent forms before they opportunistically switch to the virulent state. The molecular mechanisms underlying the transition into dormancy and emergence from it are not clear. Here we show that old cultures of Mycobacterium marinum contained spores that, upon exposure to fresh medium, germinated into vegetative cells and reappeared again in stationary phase via endospore formation. They showed many of the usual characteristics of well-known endospores. Homologues of well-known sporulation genes of Bacillus subtilis and Streptomyces coelicolor were detected in mycobacteria genomes, some of which were verified to be transcribed during appropriate life-cycle stages. We also provide data indicating that it is likely that old Mycobacterium bovis bacillus Calmette-Guérin cultures form spores. Together, our data show sporulation as a lifestyle adapted by mycobacteria under stress and tempt us to suggest this as a possible mechanism for dormancy and/or persistent infection. If so, this might lead to new prophylactic strategies.
authors.affiliation: Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala SE-751 24, Sweden.
authors.forename: Jaydip
authors.initials: J
authors.lastname: Ghosh
authors.forename: Pontus
authors.initials: P
authors.lastname: Larsson
authors.forename: Bhupender
authors.initials: B
authors.lastname: Singh
authors.forename: B M Fredrik
authors.initials: BM
authors.lastname: Pettersson
authors.forename: Nurul M
authors.initials: NM
authors.lastname: Islam
authors.forename: Sailendra Nath
authors.initials: SN
authors.lastname: Sarkar
authors.forename: Santanu
authors.initials: S
authors.lastname: Dasgupta
authors.forename: Leif A
authors.initials: LA
authors.lastname: Kirsebom
mesh_terms: D004269:DNA, Bacterial / Q000378:metabolism; D005434:Flow Cytometry; D015964:Gene Expression Regulation, Bacterial; D018507:Gene Expression Regulation, Developmental; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D019910:Mycobacterium marinum / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D009693:Nucleic Acid Hybridization / Q000379:methods; D010848:Picolinic Acids / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D013171:Spores, Bacterial / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D004269:DNA, Bacterial; D010848:Picolinic Acids; D012329:RNA, Bacterial; C004860:dipicolinic acid