HR: 1330h
AN: B12C-0803    [PDF]
TI: Nanometer-Size Iron Sulfides Biomineralized by a Deep-Sea Hydrothermal Vent Gastropod in Cooperation with Endosymbiotic Sulfate-Reducing Bacteria
AU: * Suzuki, Y
EM: yohey@jamstec.go.jp
AF: Subground Animalcule Retrieval (SUGAR) Project, Frontier Research System for Extremophiles, Japan Marine Science and Technology Center (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Kogure, T
EM: kogure@eps.s.u-tokyo.ac.jp
AF: Department of Earth and Planetary Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
AU: Takai, K
EM: kent@jamstec.go.jp
AF: Subground Animalcule Retrieval (SUGAR) Project, Frontier Research System for Extremophiles, Japan Marine Science and Technology Center (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Tsuchida, S
EM: tsuchidas@jamstec.go.jp
AF: Marine Ecosystems Research Department, Japan Marine Science and Technology Center (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Nealson, K H
EM: nealson@usc.edu
AF: Subground Animalcule Retrieval (SUGAR) Project, Frontier Research System for Extremophiles, Japan Marine Science and Technology Center (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Horikoshi, K
EM: horikoshik@jamstec.go.jp
AF: Subground Animalcule Retrieval (SUGAR) Project, Frontier Research System for Extremophiles, Japan Marine Science and Technology Center (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AB: The _gscaly-foot_h gastropod has been discovered only from a deep-sea hydrothermal field in the Central Indian Ridge among the global Mid Ocean Ridges (MOR) and found to be peculiar, because it has scale-shaped sclerites composed of hard proteins and iron sulfides that covered the sides of the foot. As the product and mechanism of the iron sulfide biomineralization have not been elucidated in any details, yet, we conducted crystallographic and molecular phylogenetic characterizations of the sclerites._@It was revealed that nanometer-scale (1) mackinawite (FeS) + greigite (Fe3S4), (2) pyrite (FeS2) and (3) mackinawite formed in distinct strata from the outer to inner parts of the sclerites, respectively. This study demonstrated for the first time that pyrite occurred in nature as exceedingly small crystalline nanoparticles (around 3 nm in diameter) and to grow via the aggregation-based pathway._@Phylogenetic analyses based on 16S rRNA and dissimilatory sulfite reductase (DSR) genes detected predominant occurrence of bacteria that have the sequences of both genes closely related to sulfate-reducing Desulfobulbus spp. Fluorescence in-situ hybridization analysis using a probe specific to the retrieved 16S rRNA gene sequences of the Desulfobulbus-related bacteria revealed the localized occurrence of the bacteria in the most inner part of the sclerites, which represents a novel structural integration between bacteria and metazoans. The results strongly suggested the potential contribution of endosymbiotic SRB to formation of stratified nanometer-scale iron sulfides inside the gastropod_fs scaly. As mackinawite that is easily oxidized under slightly oxic conditions and persisted, pyrite seems to have formed via the strictly anoxic pathway. The results presented here may provide aid in deciphering important, but still partially understood formation mechanisms and biochemical and geochemical roles of iron sulfides.
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2003 Fall Meeting