title: UV and cold tolerance of a pigment-producing Antarctic Janthinobacterium sp. Ant5-2.
abstract: In this paper, we describe the UV and cold tolerance of a purple violet pigment (PVP)-producing Antarctic bacterium, Janthinobacterium sp. Ant5-2 (PVP(+)) and compared its physiological adaptations with a pigmentless mutant strain (PVP(-)). A spontaneous deletion of vioA that codes for tryptophan monooxygenase, the first gene involved in the biosynthesis of PVP was found in PVP(-) strain. The PVP(-) culture exhibited significantly reduced survival during exponential and stationary growth phase following exposure to UVB (320 nm) and UVC (254 nm) (dose range: 0-300 J/m²) when compared to wild-type (PVP(+)) cultures. In addition, upon biochemical inhibition of pigment synthesis by 2(5H)-furanone, wild-type PVP(+) cultures exhibited approximately 50-fold growth reduction at a higher dose (300 J/m²) of UV. Increased resistance to UV was observed upon inducing starvation state in both PVP(+) and PVP(-) cultures. There was 80% (SD = ±8) reduction in extrapolymeric substance (EPS) production in the PVP(-) cultures along with a compromised survival to freeze-thaw cycles when compared to the PVP(+) cultures. Perhaps synthesis of PVP and EPS are among the key adaptive features that define the survival of this bacterium in Antarctic extreme conditions, especially during austral summer months.
authors.affiliation: Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., CH464, Birmingham, AL 35294-1170, USA.
authors.forename: Nazia
authors.initials: N
authors.lastname: Mojib
authors.forename: Amin
authors.initials: A
authors.lastname: Farhoomand
authors.forename: Dale T
authors.initials: DT
authors.lastname: Andersen
authors.forename: Asim K
authors.initials: AK
authors.lastname: Bej
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000864:Antarctic Regions; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003080:Cold Temperature; D009154:Mutation; D042802:Oxalobacteraceae / Q000235:genetics / Q000378:metabolism*; D010860:Pigments, Biological / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014365:Tryptophan Hydroxylase / Q000235:genetics / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D010860:Pigments, Biological; D014365:Tryptophan Hydroxylase