Project description:The thermophilic Aquificales inhabit and play important biogeochemical roles in the geothermal environments globally. Although intensive studies on physiology, microbial ecology, biochemistry, metagenomics and metatranscriptomics of the Aquificales¬ species and Aquificales-containing environmental samples have been conducted, comprehensive understandings about their ecophysiology, especially in the natural niches have been limited. In the present study, an integrated suite of metagenomic, metatranscriptomic and metaproteomic analyses, for the first time, were conducted on a filamentous microbial community from the Apron and Channel Facies (ACF) of CaCO3 (travertine) deposition at Narrow Gauge, Mammoth Hot Springs, Yellowstone National Park.
Project description:The thermophilic Aquificales inhabit and play important biogeochemical roles in the geothermal environments globally. Although intensive studies on physiology, microbial ecology, biochemistry, metagenomics and metatranscriptomics of the Aquificales¬ species and Aquificales-containing environmental samples have been conducted, comprehensive understandings about their ecophysiology, especially in the natural niches have been limited. In the present study, an integrated suite of metagenomic, metatranscriptomic and metaproteomic analyses, for the first time, were conducted on a filamentous microbial community from the Apron and Channel Facies (ACF) of CaCO3 (travertine) deposition at Narrow Gauge, Mammoth Hot Springs, Yellowstone National Park.
Project description:A broad survey of most of the major geyser basins within Yellowstone National Park (Wyoming, USA) was conducted to identify the flowering plants which tolerate high rhizosphere temperatures (> or = 40 degrees C) in geothermally heated environments. Under such conditions, five species of monocots and four species of dicots were repeatedly found. The predominant flowering plants in hot soils (>40 degrees C at 2-5 cm depth) were grasses, primarily Dichanthelium lanuginosum. Long-term (weeks to months) rhizosphere temperatures of individual D. lanuginosum above 40 degrees C were recorded at several different locations, both in the summer and winter. The potential role of heat shock proteins (HSPs) in the apparent adaptation of these plants to chronically high rhizosphere temperatures was examined. Antibodies to cytoplasmic class I small heat shock proteins (sHSPs) and to HSP101 were used in Western immunoblot analyses of protein extracts from plants collected from geothermally heated soils. Relatively high levels of proteins reacting with anti-sHSP antibodies were consistently detected in root extracts from plants experiencing rhizosphere temperatures above 40 degrees C, though these proteins were usually not highly expressed in leaf extracts from the same plants. Proteins reacting with antibodies to HSP101 were also present both in leaf and root extracts from plants collected from geothermal soils, but their levels of expression were not as closely related to the degree of heat exposure as those of sHSPs.
Project description:Novel lineages of the phylum Thaumarchaeota are endemic to thermal habitats, and may exhibit physiological capabilities that are not yet observed in members of this phylum. The primary goals of this study were to conduct detailed phylogenetic and functional analyses of metagenome sequence assemblies of two different thaumarchaeal populations found in high-temperature (65-72 °C), acidic (pH~3) iron oxide and sulfur sediment environments of Yellowstone National Park (YNP). Metabolic reconstruction was coupled with detailed geochemical measurements of each geothermal habitat and reverse-transcriptase PCR to confirm the in situ activity of these populations. Phylogenetic analyses of ribosomal and housekeeping proteins place these archaea near the root of the thaumarchaeal branch. Metabolic reconstruction suggests that these populations are chemoorganotrophic and couple growth with the reduction of oxygen or nitrate in iron oxide habitats, or sulfur in hypoxic sulfur sediments. The iron oxide population has the potential for growth via the oxidation of sulfide to sulfate using a novel reverse sulfate reduction pathway. Possible carbon sources include aromatic compounds (for example, 4-hydroxyphenylacetate), complex carbohydrates (for example, starch), oligopeptides and amino acids. Both populations contain a type III ribulose bisphosphate carboxylase/oxygenase used for carbon dioxide fixation or adenosine monophosphate salvage. No evidence for the oxidation of ammonia was obtained from de novo sequence assemblies. Our results show that thermoacidophilic Thaumarchaeota from oxic iron mats and hypoxic sulfur sediments exhibit different respiratory machinery depending on the presence of oxygen versus sulfide, represent deeply rooted lineages within the phylum Thaumarchaeota and are endemic to numerous sites in YNP.
Project description:An arsenite-oxidizing Hydrogenobaculum strain was isolated from a geothermal spring in Yellowstone National Park, Wyo., that was previously shown to contain microbial populations engaged in arsenite oxidation. The isolate was sensitive to both arsenite and arsenate and behaved as an obligate chemolithoautotroph that used H(2) as its sole energy source and had an optimum temperature of 55 to 60 degrees C and an optimum pH of 3.0. The arsenite oxidation in this organism displayed saturation kinetics and was strongly inhibited by H(2)S.
Project description:Here, we report on eight sediment metagenomes obtained from an alkaline hot spring, with their corresponding metagenome-assembled genomes. Samples had been incubated for 48 h with various substrate amendments in conjunction with the amino acid analog l-homopropargylglycine in a study targeted at identifying anabolicly active uncultured thermophilic archaea and bacteria.
Project description:Novel thermophilic crenarchaea have been observed in Fe(III) oxide microbial mats of Yellowstone National Park (YNP); however, no definitive work has identified specific microorganisms responsible for the oxidation of Fe(II). The objectives of the current study were to isolate and characterize an Fe(II)-oxidizing member of the Sulfolobales observed in previous 16S rRNA gene surveys and to determine the abundance and distribution of close relatives of this organism in acidic geothermal springs containing high concentrations of dissolved Fe(II). Here we report the isolation and characterization of the novel, Fe(II)-oxidizing, thermophilic, acidophilic organism Metallosphaera sp. strain MK1 obtained from a well-characterized acid-sulfate-chloride geothermal spring in Norris Geyser Basin, YNP. Full-length 16S rRNA gene sequence analysis revealed that strain MK1 exhibits only 94.9 to 96.1% sequence similarity to other known Metallosphaera spp. and less than 89.1% similarity to known Sulfolobus spp. Strain MK1 is a facultative chemolithoautotroph with an optimum pH range of 2.0 to 3.0 and an optimum temperature range of 65 to 75 degrees C. Strain MK1 grows optimally on pyrite or Fe(II) sorbed onto ferrihydrite, exhibiting doubling times between 10 and 11 h under aerobic conditions (65 degrees C). The distribution and relative abundance of MK1-like 16S rRNA gene sequences in 14 acidic geothermal springs containing Fe(III) oxide microbial mats were evaluated. Highly related MK1-like 16S rRNA gene sequences (>99% sequence similarity) were consistently observed in Fe(III) oxide mats at temperatures ranging from 55 to 80 degrees C. Quantitative PCR using Metallosphaera-specific primers confirmed that organisms highly similar to strain MK1 comprised up to 40% of the total archaeal community at selected sites. The broad distribution of highly related MK1-like 16S rRNA gene sequences in acidic Fe(III) oxide microbial mats is consistent with the observed characteristics and growth optima of Metallosphaera-like strain MK1 and emphasizes the importance of this newly described taxon in Fe(II) chemolithotrophy in acidic high-temperature environments of YNP.
Project description:Elemental sulfur (S(0)) is associated with many geochemically diverse hot springs, yet little is known about the phylogeny, physiology, and ecology of the organisms involved in its cycling. Here we report the isolation, characterization, and ecology of two novel, S(0)-reducing Crenarchaea from an acid geothermal spring referred to as Dragon Spring. Isolate 18U65 grows optimally at 70 to 72 degrees C and at pH 2.5 to 3.0, while isolate 18D70 grows optimally at 81 degrees C and pH 3.0. Both isolates are chemoorganotrophs, dependent on complex peptide-containing carbon sources, S(0), and anaerobic conditions for respiration-dependent growth. Glycerol dialkyl glycerol tetraethers (GDGTs) containing four to six cyclopentyl rings were present in the lipid fraction of isolates 18U65 and 18D70. Physiological characterization suggests that the isolates are adapted to the physicochemical conditions of Dragon Spring and can utilize the natural organic matter in the spring as a carbon and energy source. Quantitative PCR analysis of 16S rRNA genes associated with the S(0) flocs recovered from several acid geothermal springs using isolate-specific primers indicates that these two populations together represent 17 to 37% of the floc-associated DNA. The physiological characteristics of isolates 18U65 and 18D70 are consistent with their potential widespread distribution and putative role in the cycling of sulfur in acid geothermal springs throughout the Yellowstone National Park geothermal complex. Based on phenotypic and genetic characterization, the designations Caldisphaera draconis sp. nov. and Acidilobus sulfurireducens sp. nov. are proposed for isolates 18U65 and 18D70, respectively.