Extremely high UV-C radiation resistant microorganisms from desert environments with different manganese concentrations.
Desiccation resistance and a high intracellular Mn/Fe ratio contribute to ionizing radiation resistance of Deinococcus radiodurans. We hypothesized that this was a general phenomenon and thus developed a strategy to search for highly radiation-resistant organisms based on their natural environment. While desiccation is a typical feature of deserts, the correlation between radiation resistance and the intracellular Mn/Fe ratio of indigenous microorganisms or the Mn/Fe ratio of the environment, has not yet been described. UV-C radiation is highly damaging to biomolecules including DNA. It was used in this study as a selective tool because of its relevance to early life on earth, high altitude aerobiology and the search for life beyond Earth. Surface soil samples were collected from the Sonoran Desert, Arizona (USA), from the Atacama Desert in Chile and from a manganese mine in northern Argentina. Microbial isolates were selected after exposure to UV-C irradiation and growth. The isolates comprised 28 genera grouped within six phyla, which we ranked according to their resistance to UV-C irradiation. Survival curves were performed for the most resistant isolates and correlated with their intracellular Mn/Fe ratio, which was determined by ICP-MS. Five percent of the isolates were highly resistant, including one more resistant than D. radiodurans, a bacterium generally considered the most radiation-resistant organism, thus used as a model for radiation resistance studies. No correlation was observed between the occurrence of resistant microorganisms and the Mn/Fe ratio in the soil samples. However, all resistant isolates showed an intracellular Mn/Fe ratio much higher than the sensitive isolates. Our findings could represent a new front in efforts to harness mechanisms of UV-C radiation resistance from extreme environments.
NASA Postdoctoral Program Fellow at NASA Ames Research Center, Moffett Field, CA, 94035-0001, USA. Electronic address: ivan.g.paulinolima@nasa.gov.
Ivan Glaucio
IG
Paulino-Lima
University Affiliated Research Center, NASA Ames Research Center, Moffett Field, CA, 94035-0001, USA.
Kosuke
K
Fujishima
University Affiliated Research Center, NASA Ames Research Center, Moffett Field, CA, 94035-0001, USA.
Jesica Urbina
JU
Navarrete
Brazilian Synchrotron Light Laboratory, Campinas, 13083-970, Brazil.
Douglas
D
Galante
Institute of Chemistry, University of São Paulo, 05508-000, Brazil.
Fabio
F
Rodrigues
Centro de Investigación Biomédica, UniversidadAutónoma de Chile, Santiago, 8910060, Chile.
Armando
A
Azua-Bustos
NASA Ames Research Center, Moffett Field, CA, 94035-0001, USA.
Lynn Justine
LJ
Rothschild
D003889:Desert Climate; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D007501:Iron / Q000378:metabolism / Q000494:pharmacology; D008345:Manganese / Q000378:metabolism / Q000494:pharmacology*; D010802:Phylogeny; D011836:Radiation Tolerance / Q000187:drug effects*; D012988:Soil Microbiology; D014466:Ultraviolet Rays
D008345:Manganese; D007501:Iron
Desiccation; Extremophile; Manganese; Microbial diversity; Ultraviolet radiation resistance