UV and cold tolerance of a pigment-producing Antarctic Janthinobacterium sp. Ant5-2

Extremophiles. 2013 May;17(3):367-78. doi: 10.1007/s00792-013-0525-9. Epub 2013 Mar 20.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / genetics*
  • Antarctic Regions
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Cold Temperature*
  • Mutation
  • Oxalobacteraceae / genetics
  • Oxalobacteraceae / metabolism*
  • Pigments, Biological / chemistry
  • Pigments, Biological / genetics
  • Pigments, Biological / metabolism*
  • Tryptophan Hydroxylase / genetics
  • Tryptophan Hydroxylase / metabolism
  • Ultraviolet Rays*

Substances

  • Bacterial Proteins
  • Pigments, Biological
  • Tryptophan Hydroxylase