A constant flux of diverse thermophilic bacteria into the cold Arctic seabed.
Microorganisms have been repeatedly discovered in environments that do not support their metabolic activity. Identifying and quantifying these misplaced organisms can reveal dispersal mechanisms that shape natural microbial diversity. Using endospore germination experiments, we estimated a stable supply of thermophilic bacteria into permanently cold Arctic marine sediment at a rate exceeding 10(8) spores per square meter per year. These metabolically and phylogenetically diverse Firmicutes show no detectable activity at cold in situ temperatures but rapidly mineralize organic matter by hydrolysis, fermentation, and sulfate reduction upon induction at 50 degrees C. The closest relatives to these bacteria come from warm subsurface petroleum reservoir and ocean crust ecosystems, suggesting that seabed fluid flow from these environments is delivering thermophiles to the cold ocean. These transport pathways may broadly influence microbial community composition in the marine environment.
Hubert
Casey
C
Biogeochemistry Group, Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany. chubert@mpi-bremen.de
Loy
Alexander
A
Nickel
Maren
M
Arnosti
Carol
C
Baranyi
Christian
C
Brüchert
Volker
V
Ferdelman
Timothy
T
Finster
Kai
K
Christensen
Flemming Mønsted
FM
Rosa de Rezende
Júlia
J
Vandieken
Verona
V
Jørgensen
Bo Barker
BB
D000693:Anaerobiosis; D001110:Arctic Regions; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification; D018407:Bacterial Physiological Phenomena; D044822:Biodiversity; D003081:Cold Climate; D003080:Cold Temperature; D017753:Ecosystem; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005285:Fermentation; D019015:Geologic Sediments / Q000382:microbiology*; D006358:Hot Temperature; D010084:Oxidation-Reduction; D010802:Phylogeny; D013171:Spores, Bacterial / Q000502:physiology*; D013431:Sulfates / Q000378:metabolism
D005232:Fatty Acids, Volatile; D013431:Sulfates