Deep subsurface biosphere of a hydrothermal vent field in the Manus Basin of the Western Pacific

Author(s): Kimura, Hiroyuki; Naganuma, Takeshi
Author Affiliation(s): Primary:
Hiroshima University, School of Biosphere Sciences, Hiroshima, Japan
Volume Title: Life on the Earth; its origin and relevant extreme environments
Source: Life on the Earth; its origin and relevant extreme environments. Chigaku Zasshi = Journal of Geography, 112(2), p.250-261. Publisher: Tokyo Geographical Society, Tokyo, Japan. ISSN: 0022-135X CODEN: CGZAAL
Note: In Japanese with English summary. 20 refs.; illus., incl. 3 tables, sketch maps
Summary: Occurrence and distribution of microorganisms in the subsurface of deep-sea hydrothermal vents (sub-vents) were investigated using sub-vent rock samples (cores, approximately 6.5 cm in diameter) collected by the Ocean Drilling Program (ODP). The central parts of the cores (subcores, approximately 1.5 cm in diameter) were extracted in an anaerobic chamber. The degree of contamination by drilling fluid (surface seawater in ODP) was tested using perfluorocarbon (PFC) tracers. The test showed that PFC-traced contamination was limited to core surfaces and was not detected in subcores. Therefore, subcores were used in microbiological analyses for direct counts, adenosine 5-triphoshate (ATP) measurements, thermophilic incubations, and 16S ribosomal RNA gene (16S rDNA) sequences. Microbial cells in the subcores were observed from depths shallower than 97.9 meters below the seafloor (mbsf) by 4' 6'-diamidino-2-phenylindole (DAPI)-epifluorescence microscopy. Similarly, ATP was detected only from depths shallower than 44.8 mbsf by the luciferin-luciferase method. Portions of subcores from various depths, 9.7-301.5 mbsf, were directly incubated anaerobically with a heterotrophic medium at temperatures of 60°C and 90°C. After two weeks, an increase in cell numbers was observed for 60°C-cultures from 59.8-99.4 mbsf samples, and for 90°C-cultures from 69.1-128.9 mbsf samples. The 16S rDNA sequences suggest that microorganisms from the 60°C- and 90°C-cultures are closely related to the thermophilic species belonging to the genera Geobacillus and Deinococcus, respectively. These results indicate 1) existence of microbial habitats in the sub-vent region of subseafloor, and 2) habitat segregation of thermophilic bacteria over the sub-vent thermal gradient.
Year of Publication: 2003
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Bacteria; Biosphere; Bismarck Sea; Deep-sea environment; Deinococcus; Geobacillus; Geomicrobiology; Hydraulic conductivity; Hydrothermal vents; Manus Basin; Marine environment; Microorganisms; Ocean Drilling Program; Ocean floors; Oceanography; Pacific Ocean; South Pacific; Southwest Pacific; West Pacific
Coordinates: S050000 S023000 E1530000 E1480000
Record ID: 2007042030
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