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:The extent of hyperthermophilic microbial diversity associated with siliceous sinter (geyserite) was characterized in seven near-boiling silica-depositing springs throughout Yellowstone National Park using environmental PCR amplification of small-subunit rRNA genes (SSU rDNA), large-subunit rDNA, and the internal transcribed spacer (ITS). We found that Thermocrinis ruber, a member of the order Aquificales, is ubiquitous, an indication that primary production in these springs is driven by hydrogen oxidation. Several other lineages with no known close relatives were identified that branch among the hyperthermophilic bacteria. Although they all branch deep in the bacterial tree, the precise phylogenetic placement of many of these lineages is unresolved at this time. While some springs contained a fair amount of phylogenetic diversity, others did not. Within the same spring, communities in the subaqueous environment were not appreciably different than those in the splash zone at the edge of the pool, although a greater number of phylotypes was found along the pool's edge. Also, microbial community composition appeared to have little correlation with the type of sinter morphology. The number of cell morphotypes identified by fluorescence in situ hybridization and scanning electron microscopy was greater than the number of phylotypes in SSU clone libraries. Despite little variation in Thermocrinis ruber SSU sequences, abundant variation was found in the hypervariable ITS region. The distribution of ITS sequence types appeared to be correlated with distinct morphotypes of Thermocrinis ruber in different pools. Therefore, species- or subspecies-level divergences are present but not detectable in highly conserved SSU sequences.
Project description:The Heart Lake Geyser Basin (HLGB) is remotely located at the base of Mount Sheridan in southern Yellowstone National Park (YNP), Wyoming, USA and is situated along Witch Creek and the northwestern shore of Heart Lake. Likely because of its location, little is known about the microbial community structure of springs in the HLGB. Bacterial and archaeal populations were monitored via small subunit (SSU) rRNA gene pyrosequencing over 3 years in 3 alkaline (pH 8.5) hot springs with varying temperatures (44°C, 63°C, 75°C). The bacterial populations were generally stable over time, but varied by temperature. The dominant bacterial community changed from moderately thermophilic and photosynthetic members (Cyanobacteria and Chloroflexi) at 44°C to a mixed photosynthetic and thermophilic community (Deinococcus-Thermus) at 63°C and a non-photosynthetic thermophilic community at 75°C. The archaeal community was more variable across time and was predominantly a methanogenic community in the 44 and 63°C springs and a thermophilic community in the 75°C spring. The 75°C spring demonstrated large shifts in the archaeal populations and was predominantly Candidatus Nitrosocaldus, an ammonia-oxidizing crenarchaeote, in the 2007 sample, and almost exclusively Thermofilum or Candidatus Caldiarchaeum in the 2009 sample, depending on SSU rRNA gene region examined. The majority of sequences were dissimilar (?10% different) to any known organisms suggesting that HLGB possesses numerous new phylogenetic groups that warrant cultivation efforts.
Project description:The fixation of inorganic carbon has been documented in all three domains of life and results in the biosynthesis of diverse organic compounds that support heterotrophic organisms. The primary aim of this study was to assess carbon dioxide fixation in high-temperature Fe(III)-oxide mat communities and in pure cultures of a dominant Fe(II)-oxidizing organism (Metallosphaera yellowstonensis strain MK1) originally isolated from these environments. Protein-encoding genes of the complete 3-hydroxypropionate/4-hydroxybutyrate (3-HP/4-HB) carbon dioxide fixation pathway were identified in M. yellowstonensis strain MK1. Highly similar M. yellowstonensis genes for this pathway were identified in metagenomes of replicate Fe(III)-oxide mats, as were genes for the reductive tricarboxylic acid cycle from Hydrogenobaculum spp. (Aquificales). Stable-isotope ((13)CO2) labeling demonstrated CO2 fixation by M. yellowstonensis strain MK1 and in ex situ assays containing live Fe(III)-oxide microbial mats. The results showed that strain MK1 fixes CO2 with a fractionation factor of ?2.5‰. Analysis of the (13)C composition of dissolved inorganic C (DIC), dissolved organic C (DOC), landscape C, and microbial mat C showed that mat C is from both DIC and non-DIC sources. An isotopic mixing model showed that biomass C contains a minimum of 42% C of DIC origin, depending on the fraction of landscape C that is present. The significance of DIC as a major carbon source for Fe(III)-oxide mat communities provides a foundation for examining microbial interactions that are dependent on the activity of autotrophic organisms (i.e., Hydrogenobaculum and Metallosphaera spp.) in simplified natural communities.
Project description:Nanoarchaeota are obligate symbionts with reduced genomes first described from marine thermal vent environments. Here, both community metagenomics and single-cell analysis revealed the presence of Nanoarchaeota in high-temperature (∼90°C), acidic (pH ≈ 2.5 to 3.0) hot springs in Yellowstone National Park (YNP) (United States). Single-cell genome analysis of two cells resulted in two nearly identical genomes, with an estimated full length of 650 kbp. Genome comparison showed that these two cells are more closely related to the recently proposed Nanobsidianus stetteri from a more neutral YNP hot spring than to the marine Nanoarchaeum equitans. Single-cell and catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) analysis of environmental hot spring samples identified the host of the YNP Nanoarchaeota as a Sulfolobales species known to inhabit the hot springs. Furthermore, we demonstrate that Nanoarchaeota are widespread in acidic to near neutral hot springs in YNP. An integrated viral sequence was also found within one Nanoarchaeota single-cell genome and further analysis of the purified viral fraction from environmental samples indicates that this is likely a virus replicating within the YNP Nanoarchaeota.
Project description: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 3.8), which are characteristic of acid-sulfate geothermal activity. The hydrocarbon composition of the seep soils consisted almost entirely of saturated, acyclic alkanes (e.g., n-alkanes with chain lengths of C15 to C30, as well as branched alkanes, predominately pristane and phytane). Bacterial populations present in the seep soils were phylogenetically characterized by 16S rRNA gene clone library analysis. The majority of the sequences recovered (>75%) were related to sequences of heterotrophic acidophilic bacteria, including Acidisphaera spp. and Acidiphilium spp. of the alpha-Proteobacteria. Clones related to the iron- and sulfur-oxidizing chemolithotroph Acidithiobacillus spp. were also recovered from one of the seep soils. Hydrocarbon-amended soil-sand mixtures were established to examine [14C]hexadecane mineralization and corresponding changes in the bacterial populations using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. Approximately 50% of the [14C]hexadecane added was recovered as 14CO2 during an 80-day incubation, and this was accompanied by detection of heterotrophic acidophile-related sequences as dominant DGGE bands. An alkane-degrading isolate was cultivated, whose 16S rRNA gene sequence was identical to the sequence of a dominant DGGE band in the soil-sand mixture, as well as the clone sequence recovered most frequently from the original soil. This and the presence of an alkB gene homolog in this isolate confirmed the alkane degradation capability of one population indigenous to acidic hydrocarbon seep soils.
Project description:Yellowstone National Park thermal features regularly discharge various heavy metals and metalloids. These metals are taken up by microorganisms that often form mats in thermal springs. These microbial mats also serve as food sources for invertebrate assemblages. To examine how heavy metals move through insect food webs associated with hot springs, two sites were selected for this study. Dragon-Beowulf Hot Springs, acid-sulfate chloride springs, have a pH of 2.9, water temperatures above 70 °C, and populations of thermophilic bacterial, archaeal, and algal mats. Rabbit Creek Hot Springs, alkaline springs, have a pH of up to 9, some water temperatures in excess of 60 °C, and are populated with thermophilic and phototrophic bacterial mats. Mats in both hydrothermal systems form the trophic base and support active metal transfer to terrestrial food chains. In both types of springs, invertebrates bioaccumulated heavy metals including chromium, manganese, cobalt, nickel, copper, cadmium, mercury, tin and lead, and the metalloids arsenic, selenium, and antimony resulting from consuming the algal and bacterial mat biomass. At least two orders of magnitude increase in concentrations were observed in the ephydrid shore fly Paracoenia turbida, as compared to the mats for all metals except antimony, mercury, and lead. The highest bioaccumulation factor (BAF) of 729 was observed for chromium. At the other end of the food web, the invertebrate apex predator, Cicindelidia haemorrhagica, had at least a 10-fold BAF for all metals at some location-year combinations, except with antimony. Of other taxa, high BAFs were observed with zinc for Nebria sp. (2180) and for Salda littoralis (1080). This accumulation, occurring between primary producer and primary consumer trophic levels at both springs, is biomagnified through the trophic web. These observations suggest trace metals enter the geothermal food web through the microbial mat community and are then transferred through the food chain. Also, while bioaccumulation of arsenic is uncommon, we observed five instances of increases near or exceeding 10-fold: Odontomyia sp. larvae (13.6), P. turbida (34.8), C. haemorrhagica (9.7), Rhagovelia distincta (16.3), and Ambrysus mormon (42.8).