Yohey Suzuki

Heterotrophic bacteria were isolated from an acidic uranium-contaminated site. Five isolates and one reference strain, Deinococcus radiodurans, were studied for uranium accumulation and resistance to uranium. Cells were incubated in a pH 4 solution containing 80 ppm of U(VI) in the form of (UO2)2+ for 1 hr. Three isolates closely related to high G+C gram-positive bacteria were resistant to (UO2)2 +. One of the high G+C Gram-positive isolates, closely related to Arthrobacter ilicis, accumulated u

Uranium-contaminated sediment and water collected from an inactive uranium mine were incubated anaerobically with organic substrates. Stimulated microbial populations removed U almost entirely from solution within 1 month. X-ray absorption near-edge structure analysis showed that U(VI) was reduced to U(IV) during the incubation. Observations by transmission electron microscopy, selected area diffraction pattern analysis, and energy-dispersive X-ray spectroscopic analysis showed two distinct type

The fate of uranium in natural systems is of great environmental importance. X-ray absorption near-edge spectroscopy (XANES) revealed that U(VI) was reduced to U(IV) in shallow freshwater sediment at an open pit in an inactive uranium mine. Geochemical characterization of the sediment showed that nitrate, Fe(III), and sulfate had also been reduced in the sediment. Observations of the sediment particles and microbial cells by scanning and transmission electron microscopy, coupled with elemental a

The hydrothermal-vent gastropod Alviniconcha aff. hessleri from the Kairei hydrothermal field on the Central Indian Ridge houses bacterium-like cells internally in its greatly enlarged gill. A single 16S rRNA gene sequence was obtained from the DNA extract of the gill, and phylogenetic analysis placed the source organism within a lineage of the epsilon subdivision of the Proteobacteria. Fluorescence in situ hybridization analysis with an oligonucleotide probe targeting the specific epsilonproteo

Hydrothermal vent gastropods of the genus Alviniconcha are unique among metazoans in their ability to derive their nutrition from chemoautotrophic gamma- and epsilon-proteobacterial endosymbionts. Although host-symbiont relationships in Alviniconcha gastropods from the Central Indian Ridge in the Indian Ocean and the Mariana Trough in the Western Pacific have been studied extensively, host-symbiont relationships in Alviniconcha gastropods from the Southwest Pacific remain largely unknown. Phylog

Summary Here we tested U(VI) reduction by a Desulfosporosinus species (sp.) isolate and type strain (DSM 765) in cell suspensions (pH 7) containing 1mM U(VI) and lactate, under an atmosphere containing N 2 -CO 2 -H 2 (90:5:5). Although neither Desulfosporosinus species (spp.) reduced U(VI) in cell suspensions with 0.25 Na-bicarbonate or 0.85 NaCl, U(VI) was reduced in these solutions by a control strain, Desulfovibrio desulfuricans (ATCC 642). However, both Desulfosporosinus strains reduced U(VI

Understanding the behavior of uranium (U) in the environment is essential not only for the protection of aquifers from U contamination but also for predicting the fate of U and other actinides disposed of in deep geological settings. It has long been believed that the redox chemistry of U can be simply predicted by thermodynamics and that the development of a low redox potential is a sufficient condition for U reduction. However, recent studies have demonstrated that redox transformations of U a

The upper oceanic crust is mainly composed of basaltic lava that constitutes one of the largest habitable zones on Earth. However, the nature of deep microbial life in oceanic crust remains poorly understood, especially where old cold basaltic rock interacts with seawater beneath sediment. Here we show that microbial cells are densely concentrated in Fe-rich smectite on fracture surfaces and veins in 33.5- and 104-million-year-old (Ma) subseafloor basaltic rock. The Fe-rich smectite is locally e

The hydrothermal-vent gastropod Alviniconcha hessleri from the Alice Springs deep-sea hydrothermal field in the Mariana Back-Arc Basin in the Western Pacific houses an intracellular bacterial endosymbiont in its gill. Although enzymatic analysis has revealed that the endosymbiont is a sulfur-oxidizing chemoautotroph using the Calvin-Benson cycle for the fixation of carbon dioxide, the phylogenetic affiliation of, and the trophic relationship of A. hessleri with, the chemoautotrophic endosymbiont

Deep granitic aquifer is one of the largest, but least understood, microbial habitats. To avoid contamination from the surface biosphere, underground drilling was conducted for 300 m deep granitic rocks at the Mizunami underground research laboratory (URL), Japan. Slightly alkaline groundwater was characterized by low concentrations of dissolved organic matter and sulfate and the presence of > 100 nM H2 . The initial biomass was the highest (∼10(5) cells ml(-1) ) with the dominance of Hydrogenop

Microbial communities that thrive in subterranean consolidated sediments are largely unknown owing to the difficulty of extracting DNA. As this difficulty is often attributed to DNA binding onto the silica-bearing sediment matrix, we developed a DNA extraction method for consolidated sediment from the deep subsurface in which silica minerals were dissolved by being heated under alkaline conditions. NaOH concentrations (0.07 and 0.33 N), incubation temperatures (65 and 94 °C) and incubation times