Extremophiles

, Volume 9, Issue 3, pp 219–227

Physiological responses of the halophilic archaeon Halobacterium sp. strain NRC1 to desiccation and gamma irradiation

  • Molly Kottemann
  • Adrienne Kish
  • Chika Iloanusi
  • Sarah Bjork
  • Jocelyne DiRuggiero
Original Paper

DOI: 10.1007/s00792-005-0437-4

Cite this article as:
Kottemann, M., Kish, A., Iloanusi, C. et al. Extremophiles (2005) 9: 219. doi:10.1007/s00792-005-0437-4

Abstract

We report that the halophilic archaeon Halobacterium sp. strain NRC-1 is highly resistant to desiccation, high vacuum and 60Co gamma irradiation. Halobacterium sp. was able to repair extensive double strand DNA breaks (DSBs) in its genomic DNA, produced both by desiccation and by gamma irradiation, within hours of damage induction. We propose that resistance to high vacuum and 60Co gamma irradiation is a consequence of its adaptation to desiccating conditions. Gamma resistance in Halobacterium sp. was dependent on growth stage with cultures in earlier stages exhibiting higher resistance. Membrane pigments, specifically bacterioruberin, offered protection against cellular damages induced by high doses (5 kGy) of gamma irradiation. High-salt conditions were found to create a protective environment against gamma irradiation in vivo by comparing the amount of DSBs induced by ionizing radiation in the chromosomal DNA of Halobacterium sp. to that of the more radiation-sensitive Escherichia coli that grows in lower-salt conditions. No inducible response was observed after exposing Halobacterium sp. to a nonlethal dose (0.5 kGy) of gamma ray and subsequently exposing the cells to either a high dose (5 kGy) of gamma ray or desiccating conditions. We find that the hypersaline environment in which Halobacterium sp. flourishes is a fundamental factor for its resistance to desiccation, damaging radiation and high vacuum.

Keywords

HalophilesIonizing radiationDesiccationDouble-strand breaksDNA repair

Abbreviations

DSBs

Double-strand breaks

ROS

Reactive oxygen species

EMS

Ethyl methanesulfonate

Gy

Gray

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Molly Kottemann
    • 1
  • Adrienne Kish
    • 1
  • Chika Iloanusi
    • 1
  • Sarah Bjork
    • 1
  • Jocelyne DiRuggiero
    • 1
    • 2
  1. 1.Department of Cell Biology and Molecular GeneticsUniversity of MarylandCollege ParkUSA
  2. 2.Center of Marine BiotechnologyUniversity of Maryland Biotechnology InstituteBaltimoreUSA