Ancient bacteria show evidence of DNA repair.
Recent claims of cultivable ancient bacteria within sealed environments highlight our limited understanding of the mechanisms behind long-term cell survival. It remains unclear how dormancy, a favored explanation for extended cellular persistence, can cope with spontaneous genomic decay over geological timescales. There has been no direct evidence in ancient microbes for the most likely mechanism, active DNA repair, or for the metabolic activity necessary to sustain it. In this paper, we couple PCR and enzymatic treatment of DNA with direct respiration measurements to investigate long-term survival of bacteria sealed in frozen conditions for up to one million years. Our results show evidence of bacterial survival in samples up to half a million years in age, making this the oldest independently authenticated DNA to date obtained from viable cells. Additionally, we find strong evidence that this long-term survival is closely tied to cellular metabolic activity and DNA repair that over time proves to be superior to dormancy as a mechanism in sustaining bacteria viability.
Johnson
Sarah Stewart
SS
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, 54-810, Cambridge, MA 02139, USA.
Hebsgaard
Martin B
MB
Christensen
Torben R
TR
Mastepanov
Mikhail
M
Nielsen
Rasmus
R
Munch
Kasper
K
Brand
Tina
T
Gilbert
M Thomas P
MT
Zuber
Maria T
MT
Bunce
Michael
M
Rønn
Regin
R
Gilichinsky
David
D
Froese
Duane
D
Willerslev
Eske
E
D001419:Bacteria / Q000235:genetics*; D001483:Base Sequence; D004260:DNA Repair / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D005784:Gene Amplification / Q000235:genetics; D008969:Molecular Sequence Data; D012988:Soil Microbiology
D004269:DNA, Bacterial