Dense microbial community on a ferromanganese nodule from the ultra-oligotrophic South Pacific Gyre; implications for biogeochemical cycles

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doi: 10.1016/j.epsl.2016.04.021
Author(s): Shiraishi, Fumito; Mitsunobu, Satoshi; Suzuki, Katsuhiko; Hoshino, Tatsuhiko; Morono, Yuki; Inagaki, Fumio
Author Affiliation(s): Primary:
Hiroshima University, Department of Earth and Planetary Systems Science, Hiroshima, Japan
Other:
Ehime University, Japan
Japan Agency for Marine-Earth Science and Technology, Japan
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, Vol.447, p.10-20. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Includes appendix. 50 refs.; illus., incl. 2 tables, sketch map
Summary: During Integrated Ocean Drilling Program (IODP) Expedition 329, a deep-sea ferromanganese nodule and surrounding sediment were collected from the South Pacific Gyre, the most oligotrophic oceanic environment on earth. Using a combination of cryo-sectioning and fluorescence-based cell counting techniques, we determined that the microbial cell density at the very surface of the nodule was ∼108 cells cm-3, three orders of magnitude higher than that in the surrounding sediment. Analysis of bacterial and archaeal 16S rRNA gene sequences (∼1400 bp) indicated that the taxonomic composition of the nodule-associated community differed markedly from that of the sediment-associated community. Members of Marine Group I (MGI) Thaumarchaeota are potentially crucial for sustaining the high cell density because both ammonia and Cu were available on the nodule surface, making it suitable for ammonia-oxidizing chemolithoautotrophy mediated by copper enzymes. Combined cryo-sectioning and synchrotron analysis of the nodule surface revealed both hexagonal birnessite resembling δ-MnO2 and triclinic birnessite, minerals characteristic of biogenic oxide and its secondary product, respectively. Regardless of these possible biogenic features, only one gene sequence exhibited some similarity to previously identified manganese-oxidizing bacteria. On the other hand, MGI Thaumarchaeota were assumed as potential candidate of manganese oxidizers because they have multi-copper oxidase that is utilized by most known manganese oxidizers. Therefore, this archaeal group is considered to play a significant ecological role as a primary producer in biogeochemical elemental cycles in the ultra-oligotrophic abyssal plain.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Archaea; Biochemistry; Biogenic structures; Chemical composition; Communities; DNA; East Pacific; Expedition 329; Ferromanganese composition; Geochemical cycle; IODP Site U1365; IODP Site U1366; IODP Site U1369; IODP Site U1370; Integrated Ocean Drilling Program; Manganese oxides; Microorganisms; Mineral composition; Nodules; Nucleic acids; Ocean floors; Oligotrophic environment; Oxides; Pacific Ocean; RNA; Sedimentary structures; South Pacific; Southeast Pacific; Spectra; Thaumarchaeota; Whole rock; X-ray fluorescence spectra; X-ray spectra; XAFS spectra
Coordinates: S235103 S235103 W1653839 W1653839
S260305 S260305 W1565340 W1565340
S391837 S391837 W1394803 W1394803
S415107 S415107 W1530623 W1530623
Record ID: 2016062976
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands