Abundance and diversity of microbial life in ocean crust.
Oceanic lithosphere exposed at the sea floor undergoes seawater-rock alteration reactions involving the oxidation and hydration of glassy basalt. Basalt alteration reactions are theoretically capable of supplying sufficient energy for chemolithoautotrophic growth. Such reactions have been shown to generate microbial biomass in the laboratory, but field-based support for the existence of microbes that are supported by basalt alteration is lacking. Here, using quantitative polymerase chain reaction, in situ hybridization and microscopy, we demonstrate that prokaryotic cell abundances on seafloor-exposed basalts are 3-4 orders of magnitude greater than in overlying deep sea water. Phylogenetic analyses of basaltic lavas from the East Pacific Rise (9 degrees N) and around Hawaii reveal that the basalt-hosted biosphere harbours high bacterial community richness and that community membership is shared between these sites. We hypothesize that alteration reactions fuel chemolithoautotrophic microorganisms, which constitute a trophic base of the basalt habitat, with important implications for deep-sea carbon cycling and chemical exchange between basalt and sea water.
MIT/WHOI Joint Program in Oceanography and Ocean Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
Cara M
CM
Santelli
Beth N
BN
Orcutt
Erin
E
Banning
Wolfgang
W
Bach
Craig L
CL
Moyer
Mitchell L
ML
Sogin
Hubert
H
Staudigel
Katrina J
KJ
Edwards
D044822:Biodiversity; D052837:Chemoautotrophic Growth; D005798:Genes, Bacterial / Q000235:genetics; D019015:Geologic Sediments / Q000382:microbiology*; D006254:Hawaii; D049690:History, Ancient; D008386:Marine Biology; D008969:Molecular Sequence Data; D010140:Pacific Ocean; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology; D017640:Silicates / Q000378:metabolism; D014871:Water Microbiology
D012336:RNA, Ribosomal, 16S; D017640:Silicates; C060346:basalt