Publications by authors named "Natsuko Hamamura"

We report the complete genome sequences of two antimony-oxidizing bacteria, sp. strain ANAO-SY3R2, comprising one chromosome (4.3 Mbp) and four circular plasmids, and sp.

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Yaku sika deer (Cervus nippon yakushimae) are endemic to Yakushima Island, whose landscape covered with primary evergreen forest is recognized as a World Heritage Site. In this study, the rumen bacterial microbiota (RBM) of wild Yaku sika was characterized using high throughput sequencing of bacterial 16S rRNA genes combined with targeted cultivation and functional analyses. Comparative analyses of RBM datasets from other ruminant animals revealed distinct community structure among domesticated and wild ruminants.

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The draft genome sequence of sp. strain ANAO-440 contains 3,866 predicted protein-coding sequences. This strain is capable of anaerobic arsenite oxidation and encodes an -type arsenite oxidase within the gene island.

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sp. strain IK-TO18 was isolated from antimony-contaminated sediment. The draft genome sequence of the isolate contains 6,605 predicted protein-coding sequences, including genes associated with heavy metal resistance and the aerobic degradation of aromatic hydrocarbons.

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The antimony-oxidizing sp. strain SbOxS2 was isolated from stibnite mine tailing soil. The draft genome sequence of strain SbOxS2 comprises 4.

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sp. strain SbOxS1 was isolated from stibnite mine tailing soil for its ability to oxidize antimonite. We present a draft genome sequence of strain SbOxS1, which contains 6,484 predicted protein-coding sequences.

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The reduction of arsenate [As(V)] to arsenite [As(III)] by dissimilatory As(V)-reducing bacteria, such as spp., may play a significant role in arsenic release from anaerobic sediments into groundwater. The biochemical and molecular mechanisms by which these bacteria cope with this toxic element remain unclear.

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In the present study, the influence of the co-contamination with various chemical forms of antimony (Sb) with arsenite (As[III]) on soil microbial communities was investigated. The oxidation of As(III) to As(V) was monitored in soil columns amended with As(III) and three different chemical forms of Sb: antimony potassium tartrate (Sb[III]-tar), antimony(III) oxide (SbO), and potassium antimonate (Sb[V]). Soil microbial communities were examined qualitatively and quantitatively using 16S rDNA- and arsenite oxidase gene (aioA)-targeted analyses.

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Arsenic (As) is a widely distributed toxic element in the environment and microorganisms have developed resistance mechanisms in order to tolerate it. The cellular response of the chemoorganotrophic arsenite (As[III])-oxidizing α-Proteobacteria, Sinorhizobium sp. strain A2, to arsenic was examined in the present study.

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Toward the development of ecotoxicology methods to investigate microbial markers of impacts of hydrocarbon processing activities, DNA adductomic analyses were conducted on a sphingomonad soil bacterium. From growing cells that were exposed or unexposed to acrolein, a commonly used biocide in hydraulic fracturing processes, DNA was extracted, digested to 2'-deoxynucleosides and analyzed by liquid chromatography-positive ionization electrospray-tandem mass spectrometry in selected reaction monitoring mode transmitting the [M + H](+) > [M + H - 116](+) transition over 100 transitions. Overall data shown as DNA adductome maps revealed numerous putative DNA adducts under both conditions with some occurring specifically for each condition.

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Microbial arsenic transformation pathways associated with a saline lake located in northern Mongolia were examined using molecular biological and culturing approaches. Bacterial 16S rRNA gene sequences recovered from saline lake sediments and soils were affiliated with haloalkaliphiles, including Bacillus and Halomonas spp. Diverse sequences of arsenate respiratory reductase (arrA) and a new group of arsenite oxidase (arxA) genes were also identified.

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The Aquificales are thermophilic microorganisms that inhabit hydrothermal systems worldwide and are considered one of the earliest lineages of the domain Bacteria. We analyzed metagenome sequence obtained from six thermal "filamentous streamer" communities (∼40 Mbp per site), which targeted three different groups of Aquificales found in Yellowstone National Park (YNP). Unassembled metagenome sequence and PCR-amplified 16S rRNA gene libraries revealed that acidic, sulfidic sites were dominated by Hydrogenobaculum (Aquificaceae) populations, whereas the circum-neutral pH (6.

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A soil bacterium, designated strain KK22, was isolated from a phenanthrene enrichment culture of a bacterial consortium that grew on diesel fuel, and it was found to biotransform the persistent environmental pollutant and high-molecular-weight polycyclic aromatic hydrocarbon (PAH) benz[a]anthracene. Nearly complete sequencing of the 16S rRNA gene of strain KK22 and phylogenetic analysis revealed that this organism is a new member of the genus Sphingobium. An 8-day time course study that consisted of whole-culture extractions followed by high-performance liquid chromatography (HPLC) analyses with fluorescence detection showed that 80 to 90% biodegradation of 2.

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Antimony (Sb) is a naturally occurring toxic element commonly associated with arsenic (As) in the environment and both elements have similar chemistry and toxicity. Increasing numbers of studies have focused on microbial As transformations, while microbial Sb interactions are still not well understood. To gain insight into microbial roles in the geochemical cycling of Sb and As, soils from Sb mine tailing were examined for the presence of Sb- and As-oxidizing bacteria.

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Transformation of 9,10-phenanthrenedione, a cytotoxic derivative of phenanthrene, was shown to occur by a soil bacterium belonging to the genus Sphingobium. Phenanthrene-grown cells of this strain were exposed to 50mgL(-1) 9,10-phenanthrenedione in liquid cultures, extracted, and extracts were analyzed by liquid chromatography electrospray ionization mass spectrometry in negative ionization mode. Full scan analyses of exposed cells over the range from m/z 50 to m/z 500 were compared to abiotic and biotic controls.

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Soil bacterial population dynamics were examined to assess patterns in microbial response to contamination by different petroleum mixtures with variation in n-alkane profiles or toxic constituents such as pentachlorophenol (PCP). Three soil types from distinct areas of the United States (Montana, Oregon, and Arizona) were used in controlled perturbation experiments containing crude oil, kerosene, diesel, or diesel plus PCP spiked with (14)C-hexadecane or (14)C-tridecane. After a 50-day incubation, 30-70% of added (14)C-alkanes were mineralized to (14)CO₂ in Montana and Oregon soils.

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Members of Sulfurihydrogenibium are often observed as visible filamentous biomass in circumneutral hot springs and play roles in sulfur-cycling, hydrogen oxidation and iron mineralization. To gain insight into the ecophysiology of Sulfurihydrogenibium populations, we conducted preliminary metatranscriptomic analysis of three distinct thermal springs; Calcite Springs (YNP-CS) and Mammoth Springs (YNP-MHS) in Yellowstone National Park, USA, and Furnas Springs (AZ) in Azores, Portugal. Genes to which transcripts were assigned revealed commonly expressed functions among the sites, while several differences were also observed.

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Phototrophic microbial mat communities from 60°C and 65°C regions in the effluent channels of Mushroom and Octopus Springs (Yellowstone National Park, WY, USA) were investigated by shotgun metagenomic sequencing. Analyses of assembled metagenomic sequences resolved six dominant chlorophototrophic populations and permitted the discovery and characterization of undescribed but predominant community members and their physiological potential. Linkage of phylogenetic marker genes and functional genes showed novel chlorophototrophic bacteria belonging to uncharacterized lineages within the order Chlorobiales and within the Kingdom Chloroflexi.

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The Gram-positive bacterium Nocardioides sp. strain CF8 uses a membrane-associated monooxygenase (pBMO) to grow on butane. The nucleotide sequences of the genes encoding this novel monooxygenase were revealed through analysis of a de novo assembled draft genome sequence determined by high-throughput sequencing of the whole genome.

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Article Synopsis
  • * Five high-temperature microbial communities were sampled, revealing significant differences in dominant microbial phyla based on varying geochemical conditions like pH and oxygen levels.
  • * The study highlights novel archaeal groups and suggests that distinct metabolic strategies exist among these microorganisms, as indicated by the presence of specific functional genes related to energy processes.
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The effect of temperature as a determinant for selecting microbial populations associated with alkane-degradation was examined in crude oil-amended soil microcosms. After a 30-day incubation, >95% of n-alkane components in the crude-oil were depleted and approximately 40 and 60% of added [14C] hexadecane was converted to 14CO2 at 4-10 and 25 degrees C, respectively. Concomitant with crude-oil depletion, 16S rRNA gene sequence analysis revealed the emergence of a prominent Rhodococcus-like 16S rRNA sequence at all temperatures and a prominent Pseudomonas-like sequence at 4 and 10 degrees C.

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In microbial mat communities of Yellowstone hot springs, ribosomal RNA (rRNA) sequence diversity patterns indicate the presence of closely related bacterial populations along environmental gradients of temperature and light. To identify the functional bases for adaptation, we sequenced the genomes of two cyanobacterial (Synechococcus OS-A and OS-B') isolates representing ecologically distinct populations that dominate at different temperatures and are major primary producers in the mat. There was a marked lack of conserved large-scale gene order between the two Synechococcus genomes, indicative of extensive genomic rearrangements.

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The arsenic (As) drinking water crisis in south and south-east Asia has stimulated intense study of the microbial processes controlling the redox cycling of As in soil-water systems. Microbial oxidation of arsenite is a critical link in the global As cycle, and phylogenetically diverse arsenite-oxidizing microorganisms have been isolated from various aquatic and soil environments. However, despite progress characterizing the metabolism of As in various pure cultures, no functional gene approaches have been developed to determine the importance and distribution of arsenite-oxidizing genes in soil-water-sediment systems.

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Soil bacterial population dynamics were examined in several crude-oil-contaminated soils to identify those organisms associated with alkane degradation and to assess patterns in microbial response across disparate soils. Seven soil types obtained from six geographically distinct areas of the United States (Arizona, Oregon, Indiana, Virginia, Oklahoma, and Montana) were used in controlled contamination experiments containing 2% (wt/wt) crude oil spiked with [1-(14)C]hexadecane. Microbial populations present during hydrocarbon degradation were analyzed using both 16S rRNA gene sequence analysis and by traditional methods for cultivating hydrocarbon-oxidizing bacteria.

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In this paper we describe the bacterial communities associated with natural hydrocarbon seeps in nonthermal soils at Rainbow Springs, Yellowstone National Park. Soil chemical analysis revealed high sulfate concentrations and low pH values (pH 2.8 to 3.

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