title: The cyst-dividing bacterium Ramlibacter tataouinensis TTB310 genome reveals a well-stocked toolbox for adaptation to a desert environment.
abstract: Ramlibacter tataouinensis TTB310(T) (strain TTB310), a betaproteobacterium isolated from a semi-arid region of South Tunisia (Tataouine), is characterized by the presence of both spherical and rod-shaped cells in pure culture. Cell division of strain TTB310 occurs by the binary fission of spherical "cyst-like" cells ("cyst-cyst" division). The rod-shaped cells formed at the periphery of a colony (consisting mainly of cysts) are highly motile and colonize a new environment, where they form a new colony by reversion to cyst-like cells. This unique cell cycle of strain TTB310, with desiccation tolerant cyst-like cells capable of division and desiccation sensitive motile rods capable of dissemination, appears to be a novel adaptation for life in a hot and dry desert environment. In order to gain insights into strain TTB310's underlying genetic repertoire and possible mechanisms responsible for its unusual lifestyle, the genome of strain TTB310 was completely sequenced and subsequently annotated. The complete genome consists of a single circular chromosome of 4,070,194 bp with an average G+C content of 70.0%, the highest among the Betaproteobacteria sequenced to date, with total of 3,899 predicted coding sequences covering 92% of the genome. We found that strain TTB310 has developed a highly complex network of two-component systems, which may utilize responses to light and perhaps a rudimentary circadian hourglass to anticipate water availability at the dew time in the middle/end of the desert winter nights and thus direct the growth window to cyclic water availability times. Other interesting features of the strain TTB310 genome that appear to be important for desiccation tolerance, including intermediary metabolism compounds such as trehalose or polyhydroxyalkanoate, and signal transduction pathways, are presented and discussed.
authors.affiliation: CEA, Lab Ecol Microbienne Rhizosphere & Environm Extre, iBEB, DSV, Saint-Paul-lez-Durance, France. gilles.deluca@cea.fr
authors.forename: Gilles
authors.initials: G
authors.lastname: De Luca
authors.forename: Mohamed
authors.initials: M
authors.lastname: Barakat
authors.forename: Philippe
authors.initials: P
authors.lastname: Ortet
authors.forename: Sylvain
authors.initials: S
authors.lastname: Fochesato
authors.forename: Cécile
authors.initials: C
authors.lastname: Jourlin-Castelli
authors.forename: Mireille
authors.initials: M
authors.lastname: Ansaldi
authors.forename: Béatrice
authors.initials: B
authors.lastname: Py
authors.forename: Gwennaele
authors.initials: G
authors.lastname: Fichant
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Coutinho
authors.forename: Romé
authors.initials: R
authors.lastname: Voulhoux
authors.forename: Olivier
authors.initials: O
authors.lastname: Bastien
authors.forename: Eric
authors.initials: E
authors.lastname: Maréchal
authors.forename: Bernard
authors.initials: B
authors.lastname: Henrissat
authors.forename: Yves
authors.initials: Y
authors.lastname: Quentin
authors.forename: Philippe
authors.initials: P
authors.lastname: Noirot
authors.forename: Alain
authors.initials: A
authors.lastname: Filloux
authors.forename: Vincent
authors.initials: V
authors.lastname: Méjean
authors.forename: Michael S
authors.initials: MS
authors.lastname: DuBow
authors.forename: Frédéric
authors.initials: F
authors.lastname: Barras
authors.forename: Valérie
authors.initials: V
authors.lastname: Barbe
authors.forename: Jean
authors.initials: J
authors.lastname: Weissenbach
authors.forename: Irina
authors.initials: I
authors.lastname: Mihalcescu
authors.forename: André
authors.initials: A
authors.lastname: Verméglio
authors.forename: Wafa
authors.initials: W
authors.lastname: Achouak
authors.forename: Thierry
authors.initials: T
authors.lastname: Heulin
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics* / Q000528:radiation effects; D050260:Carbohydrate Metabolism / Q000235:genetics / Q000528:radiation effects; D002455:Cell Division / Q000235:genetics* / Q000528:radiation effects; D002462:Cell Membrane / Q000378:metabolism / Q000528:radiation effects; D002465:Cell Movement / Q000235:genetics / Q000528:radiation effects; D048430:Cell Shape / Q000235:genetics / Q000528:radiation effects; D002940:Circadian Rhythm / Q000235:genetics / Q000528:radiation effects; D042621:Comamonadaceae / Q000166:cytology* / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D004260:DNA Repair / Q000235:genetics / Q000528:radiation effects; D004269:DNA, Bacterial / Q000235:genetics; D003889:Desert Climate; D005110:Extracellular Space / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D005227:Fatty Acids / Q000378:metabolism; D016680:Genome, Bacterial; D023281:Genomics; D006868:Hydrolysis / Q000528:radiation effects; D008027:Light; D008560:Membrane Fluidity / Q000235:genetics / Q000528:radiation effects; D008563:Membrane Lipids / Q000378:metabolism; D009997:Osmotic Pressure / Q000528:radiation effects; D018384:Oxidative Stress / Q000235:genetics / Q000528:radiation effects; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics / Q000528:radiation effects; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics / Q000528:radiation effects; D014199:Trehalose / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D008563:Membrane Lipids; D011135:Polysaccharides, Bacterial; D014199:Trehalose