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Anna-Louise Reysenbach

Publications and source records attributed to Anna-Louise Reysenbach.

12 recordsLinked to original sources
PubMed2006

A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents.

Deep-sea hydrothermal vents are important in global biogeochemical cycles, providing biological oases at the sea floor that are supported by the thermal and chemical flux from the Earth's interior. As hot, acidic and reduced hydrothermal fluids mix with cold, alkaline and oxygenated sea water, minerals precipitate to form porous sulphide-sulphate deposits. These structures provide microhabitats for a diversity of prokaryotes that exploit the geochemical and physical gradients in this dynamic ecosystem. It has been proposed that fluid pH in the actively venting sulphide structures is generally low (pH < 4.5), yet no extreme thermoacidophile has been isolated from vent deposits. Culture-independent surveys based on ribosomal RNA genes from deep-sea hydrothermal deposits have identified a widespread euryarchaeotal lineage, DHVE2 (deep-sea hydrothermal vent euryarchaeotic 2). Despite the ubiquity and apparent deep-sea endemism of DHVE2, cultivation of this group has been unsuccessful and thus its metabolism remains a mystery. Here we report the isolation and cultivation of a member of the DHVE2 group, which is an obligate thermoacidophilic sulphur- or iron-reducing heterotroph capable of growing from pH 3.3 to 5.8 and between 55 and 75 degrees C. In addition, we demonstrate that this isolate constitutes up to 15% of the archaeal population, providing evidence that thermoacidophiles may be key players in the sulphur and iron cycling at deep-sea vents.

Acids↗
PubMed2006

New opportunities revealed by biotechnological explorations of extremophiles.

Over the past few decades the extremes at which life thrives has continued to challenge our understanding of biochemistry, biology and evolution. As more new extremophiles are brought into laboratory culture, they have provided a multitude of potential applications for biotechnology. More recently, innovative culturing approaches, environmental genome sequencing and whole genome sequencing have provided new opportunities for the biotechnological exploration of extremophiles.

Archaea↗
PubMed2006

Microbial biogeography: putting microorganisms on the map.

We review the biogeography of microorganisms in light of the biogeography of macroorganisms. A large body of research supports the idea that free-living microbial taxa exhibit biogeographic patterns. Current evidence confirms that, as proposed by the Baas-Becking hypothesis, 'the environment selects' and is, in part, responsible for spatial variation in microbial diversity. However, recent studies also dispute the idea that 'everything is everywhere'. We also consider how the processes that generate and maintain biogeographic patterns in macroorganisms could operate in the microbial world.

Archaea↗
PubMed2003

Archaeal diversity associated with in situ samplers deployed on hydrothermal vents on the East Pacific Rise (13 degrees N).

To evaluate possible compositional changes in archaeal communities at a deep-sea hydrothermal vent field scale, we examined five different samples obtained after deploying in situ collectors for different times on three spatially separated venting sulphide structures on the East Pacific Rise (13 degrees N). Direct cell counts and whole-cell hybridizations with fluorescently labelled 16S rRNA-based oligonucleotide probes revealed that the relative abundance of archaeal populations represented from 14 to 33% of the prokaryotic community. 16S rDNA sequence analysis of the archaeal clone libraries indicated that a large percentage of clones were closely related to known archaeal isolates recovered from similar habitats. Among the 24 different phylotypes identified, Thermococcales-related sequences were dominant in all the libraries that also included representative genera of orders Methanopyrales, Methanococcales, Archaeoglobales and Desulfurococcales. The presence of most of these phylogenetic groups was confirmed in enrichment cultures performed at temperatures from 60 to 90 degrees C. Additional sequences with no known cultivated relatives grouped with the Marine group I Crenarchaeota, Korarchaeota and Deep-sea Hydrothermal Vent Euryarchaeota (DHVE) within which a novel lineage was identified. Furthermore, the archaeal community composition was distinct from vent to vent within the same vent field and varied within short time scales. This study provides new insights into microbial diversity and distribution at deep-sea hydrothermal vents.

Archaea↗
PubMed2002

Merging genomes with geochemistry in hydrothermal ecosystems.

Thermophilic microbial inhabitants of active seafloor and continental hot springs populate the deepest branches of the universal phylogenetic tree, making hydrothermal ecosystems the most ancient continuously inhabited ecosystems on Earth. Geochemical consequences of hot water-rock interactions render these environments habitable and supply a diverse array of energy sources. Clues to the strategies for how life thrives in these dynamic ecosystems are beginning to be elucidated through a confluence of biogeochemistry, microbiology, ecology, molecular biology, and genomics. These efforts have the potential to reveal how ecosystems originate, the extent of the subsurface biosphere, and the driving forces of evolution.

Adaptation, Physiological↗
PubMed2002

Carbon isotopic fractionations associated with thermophilic bacteria Thermotoga maritima and Persephonella marina.

Stable carbon isotopes can provide insight into carbon cycling pathways in natural environments. We examined carbon isotope fractionations associated with a hyperthermophilic fermentative bacterium, Thermotoga maritima, and a thermophilic chemolithoautotrophic bacterium Persephonella marina. In T. maritima, phospholipid fatty acids (PLFA) are slightly enriched in 13C relative to biomass (epsilon = 0.1-0.8 per thousand). However, PLFA and biomass are depleted in 13C relative to the substrate glucose by approximately 8 per thousand. In P. marina, PLFA are 1.8-14.5 per thousand enriched in 13C relative to biomass, which suggests that the reversed tricarboxylic acid (TCA) cycle or the 3-hydroxypropionate pathway may be used for CO2 fixation. This is supported by small fractionation between biomass and CO2 (epsilon = -3.8 per thousand to -5.0 per thousand), which is similar to fractionations reported for other organisms using similar CO2 fixation pathways. Identification of the exact pathway will require biochemical assay for specific enzymes associated with the reversed TCA cycle or the 3-hydroxypropionate pathway.

Carbon Dioxide↗
PubMed2002

Geoglobus ahangari gen. nov., sp. nov., a novel hyperthermophilic archaeon capable of oxidizing organic acids and growing autotrophically on hydrogen with Fe(III) serving as the sole electron acceptor.

A novel, regular to irregular, coccoid-shaped, anaerobic, Fe(III)-reducing microorganism was isolated from the Guaymas Basin hydrothermal system at a depth of 2000 m. Isolation was carried out with a new technique using Fe(III) oxide as the electron acceptor for the recovery of colonies on solid medium. The isolate, designated strain 234T, was strictly anaerobic and exhibited a tumbling motility. The cells had a single flagellum. Strain 234T grew at temperatures between 65 and 90 degrees C, with an optimum at about 88 degrees C. The optimal salt concentration for growth was around 19 g l(-1). The isolate was capable of growth with H2 as the sole electron donor coupled to the reduction of Fe(III) without the need for an organic carbon source. This is the first example of a dissimilatory Fe(III)-reducing micro-organism capable of growing autotrophically on hydrogen. In addition to molecular hydrogen, strain 234T oxidizes pyruvate, acetate, malate, succinate, peptone, formate, fumarate, yeast extract, glycerol, isoleucine, arginine, serine, glutamine, asparagine, stearate, palmitate, valerate, butyrate and propionate with the reduction of Fe(III). This isolate is the first example of a hyperthermophile capable of oxidizing long-chain fatty acids anaerobically. Isolate 234T grew exclusively with Fe(III) as the sole electron acceptor. The G+C content was 58.7 mol%. Based on detailed analysis of its 16S rDNA sequence, G+C content, distinguishing physiological features and metabolism, strain 234T is proposed to represent a novel genus within the Archaeoglobales. The name proposed for strain 234T is Geoglobus ahangari gen. nov., sp. nov..

Anaerobiosis↗
PubMed2002

Thermodesulfobacterium hydrogeniphilum sp. nov., a thermophilic, chemolithoautotrophic, sulfate-reducing bacterium isolated from a deep-sea hydrothermal vent at Guaymas Basin, and emendation of the genus Thermodesulfobacterium.

A thermophilic, non-spore-forming, marine, sulfate-reducing bacterium, strain SL6T, was isolated from deep-sea hydrothermal sulfides collected at Guaymas Basin. The gram-negative-staining cells occurred singly or in pairs as small, highly motile rods. The temperature range for growth was 50-80 degrees C with an optimum at 75 degrees C. The pH range for growth at 70 degrees C was 6.3-6.8, with an optimum at 6.5. The NaCl concentration range for growth was 5-55 g l(-1), with an optimum at 30 g l(-1). H2 and CO2 were the only substrates for growth and sulfate reduction. However, growth was stimulated by several organic compounds. Sulfur, thiosulfate, sulfite, cystine, nitrate and fumarate were not used as electron acceptors. Pyruvate, lactate and malate did not support fermentative growth. Desulfoviridin was not detected. The G+C content of the genomic DNA was 28 mol%. On the basis of 16S rRNA sequence analysis, strain SL6T is related to members of the genus Thermodesulfobacterium. However, the novel organism possesses phenotypic and phylogenetic traits that differ from those of its closest relatives. Therefore, it is proposed that this isolate, which constitutes the first marine representative of this genus, should be described as the type strain of a novel species, Thermodesulfobacterium hydrogeniphilum sp. nov. The type strain is SL6T (= DSM 14290T = JCM 11239T). Because of the phenotypic characteristics of the novel species, it is also proposed that the description of the genus Thermodesulfobacterium requires emendation.

Bacterial Typing Techniques↗
PubMed2002

Use of Fe(III) as an electron acceptor to recover previously uncultured hyperthermophiles: isolation and characterization of Geothermobacterium ferrireducens gen. nov., sp. nov.

It has recently been recognized that the ability to use Fe(III) as a terminal electron acceptor is a highly conserved characteristic in hyperthermophilic microorganisms. This suggests that it may be possible to recover as-yet-uncultured hyperthermophiles in pure culture if Fe(III) is used as an electron acceptor. As part of a study of the microbial diversity of the Obsidian Pool area in Yellowstone National Park, Wyo., hot sediment samples were used as the inoculum for enrichment cultures in media containing hydrogen as the sole electron donor and poorly crystalline Fe(III) oxide as the electron acceptor. A pure culture was recovered on solidified, Fe(III) oxide medium. The isolate, designated FW-1a, is a hyperthermophilic anaerobe that grows exclusively by coupling hydrogen oxidation to the reduction of poorly crystalline Fe(III) oxide. Organic carbon is not required for growth. Magnetite is the end product of Fe(III) oxide reduction under the culture conditions evaluated. The cells are rod shaped, about 0.5 microm by 1.0 to 1.2 microm, and motile and have a single flagellum. Strain FW-1a grows at circumneutral pH, at freshwater salinities, and at temperatures of between 65 and 100 degrees C with an optimum of 85 to 90 degrees C. To our knowledge this is the highest temperature optimum of any organism in the Bacteria. Analysis of the 16S ribosomal DNA (rDNA) sequence of strain FW-1a places it within the Bacteria, most closely related to abundant but uncultured microorganisms whose 16S rDNA sequences have been previously recovered from Obsidian Pool and a terrestrial hot spring in Iceland. While previous studies inferred that the uncultured microorganisms with these 16S rDNA sequences were sulfate-reducing organisms, the physiology of the strain FW-1a, which does not reduce sulfate, indicates that these organisms are just as likely to be Fe(III) reducers. These results further demonstrate that Fe(III) may be helpful for recovering as-yet-uncultured microorganisms from hydrothermal environments and illustrate that caution must be used in inferring the physiological characteristics of at least some thermophilic microorganisms solely from 16S rDNA sequences. Based on both its 16S rDNA sequence and physiological characteristics, strain FW-1a represents a new genus among the Bacteria. The name Geothermobacterium ferrireducens gen. nov., sp. nov., is proposed (ATCC BAA-426).

Bacterial Typing Techniques↗
PubMedDate not supplied

Vannella epipetala n. sp. isolated from the leaf surface of Spondias mombin (Anacardiaceae) growing in the dry forest of Costa Rica.

As part of a Microbial Observatory of Caterpillars located in the Area de Conservacíon Guanacaste (ACG) in northwestern Costa Rica, we isolated a novel species of the genus Vannella associated with the food of the caterpillars of the saturniid moth Rothschildia lebeau, namely the leaves of the dry forest deciduous tree Spondias mombin (Anacardiaceae). The new species can be distinguished from other described species of the genus by the presence of a plasmalemma coated with a thickened, osmiophilic lamina containing glycostyles, and by its unusual habitat, the leaf surfaces or phylosphere of S. mombin. We further established the novelty of our isolate by sequencing its nuclear small-subunit (SSU) rRNA gene and inferring its phylogenetic position among all other currently sequenced members of the genera Vannella and Platyamoeba. Our results reveal that our isolate shares most recent common ancestry with three strains of Platyamoeba placida, the type species of the genus Platyamoeba. Despite this placement, the isolate clearly possesses glycostyles that are the hallmark of the genus Vannella. In addition to the cultured isolate, we also present a closely related sequence from a SSU rRNA gene clone library constructed from a DNA extract of leaf-wash of S. mombin with sterile water.

Anacardiaceae↗