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1.
Proc Natl Acad Sci U S A ; 111(5): E537-45, 2014 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-24459183

RESUMEN

The ecology and dynamics of many microbial systems, particularly in mats and soils, are shaped by how bacteria respond to evolving nutrient gradients and microenvironments. Here we show how the response of the sulfur-oxidizing bacterium Thiovulum majus to changing oxygen gradients causes cells to organize into large-scale fronts. To study this phenomenon, we develop a technique to isolate and enrich these bacteria from the environment. Using this enrichment culture, we observe the formation and dynamics of T. majus fronts in oxygen gradients. We show that these dynamics can be understood as occurring in two steps. First, chemotactic cells moving up the oxygen gradient form a front that propagates with constant velocity. We then show, through observation and mathematical analysis, that this front becomes unstable to changes in cell density. Random perturbations in cell density create oxygen gradients. The response of cells magnifies these gradients and leads to the formation of millimeter-scale fluid flows that actively pull oxygenated water through the front. We argue that this flow results from a nonlinear instability excited by stochastic fluctuations in the density of cells. Finally, we show that the dynamics by which these modes interact can be understood from the chemotactic response of cells. These results provide a mathematically tractable example of how collective phenomena in ecological systems can arise from the individual response of cells to a shared resource.


Asunto(s)
Epsilonproteobacteria/fisiología , Hidrodinámica , Epsilonproteobacteria/citología , Epsilonproteobacteria/efectos de los fármacos , Modelos Biológicos , Dinámicas no Lineales , Oxígeno/farmacología , Agua
2.
Environ Microbiol ; 17(10): 4063-77, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26147346

RESUMEN

Little is known about how lithoautotrophic primary production is connected to microbial organotrophic consumption in hydrothermal systems. Using a multifaceted approach, we analysed the structure and metabolic capabilities within a biofilm growing on the surface of a black smoker chimney in the Loki's Castle vent field. Imaging revealed the presence of rod-shaped Bacteroidetes growing as ectobionts on long, sheathed microbial filaments (> 100 µm) affiliated with the Sulfurovum genus within Epsilonproteobacteria. The filaments were composed of a thick (> 200 nm) stable polysaccharide, representing a substantial fraction of organic carbon produced by primary production. An integrated -omics approach enabled us to assess the metabolic potential and in situ metabolism of individual taxonomic and morphological groups identified by imaging. Specifically, we provide evidence that organotrophic Bacteroidetes attach to and glide along the surface of Sulfurovum filaments utilizing organic polymers produced by the lithoautotrophic Sulfurovum. Furthermore, in situ expression of acetyl-CoA synthetase by Sulfurovum suggested the ability to assimilate acetate, indicating recycling of organic matter in the biofilm. This study expands our understanding of the lifestyles of Epsilonproteobacteria in hydrothermal vents, their metabolic properties and co-operative interactions in deep-sea hydrothermal vent food webs.


Asunto(s)
Bacteroidetes/fisiología , Biopelículas , Coenzima A Ligasas/metabolismo , Epsilonproteobacteria/fisiología , Respiraderos Hidrotermales/microbiología , Interacciones Microbianas , Acetatos/metabolismo , Acetilcoenzima A/biosíntesis , Bacteroidetes/genética , Coenzima A Ligasas/biosíntesis , Epsilonproteobacteria/genética , Filogenia , ARN Ribosómico 16S/genética
3.
Phys Rev Lett ; 114(15): 158102, 2015 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-25933342

RESUMEN

We investigate a new form of collective dynamics displayed by Thiovulum majus, one of the fastest-swimming bacteria known. Cells spontaneously organize on a surface into a visually striking two-dimensional hexagonal lattice of rotating cells. As each constituent cell rotates its flagella, it creates a tornadolike flow that pulls neighboring cells towards and around it. As cells rotate against their neighbors, they exert forces on one another, causing the crystal to rotate and cells to reorganize. We show how these dynamics arise from hydrodynamic and steric interactions between cells. We derive the equations of motion for a crystal, show that this model explains several aspects of the observed dynamics, and discuss the stability of these active crystals.


Asunto(s)
Epsilonproteobacteria/fisiología , Cristalización , Epsilonproteobacteria/química , Epsilonproteobacteria/citología , Flagelos/fisiología , Hidrodinámica , Modelos Biológicos , Natación
4.
Environ Microbiol ; 15(5): 1580-94, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23368413

RESUMEN

Barrier zones between oxic and anoxic water masses (redoxclines) host highly active prokaryotic communities with important roles in biogeochemical cycling. In Baltic Sea pelagic redoxclines, Epsilonproteobacteria of the genus Sulfurimonas (subgroup GD17) have been shown to dominate chemoautotrophic denitrification. However, little is known on the loss processes affecting this prokaryotic group. In the present study, the protist grazing impact on the Sulfurimonas subgroup GD17 was determined for suboxic and oxygen/hydrogen sulphide interface depths of Baltic Sea redoxclines, using predator exclusion assays and bacterial amendment with the cultured representative 'Sulfurimonas gotlandica' strain GD1. Additionally, the principal bacterivores were identified by RNA-Stable Isotope Probing (RNA-SIP). The natural Sulfurimonas subgroup GD17 population grew strongly under oxygen/hydrogen sulphide interface conditions (doubling time: 1-1.5 days), but protist grazing could consume the complete new cell production per day. In suboxic samples, little or no growth of Sulfurimonas subgroup GD17 was observed. RNA-SIP identified five active grazers, belonging to typical redoxcline ciliates (Oligohymenophorea, Prostomatea) and globally widespread marine flagellate groups (MAST-4, Chrysophyta, Cercozoa). Overall, we demonstrate for the first time that protist grazing can control the growth, and potentially the vertical distribution, of a chemolithoautotrophic key-player of oxic/anoxic interfaces.


Asunto(s)
Chrysophyta/metabolismo , Cilióforos/metabolismo , Epsilonproteobacteria/fisiología , Agua de Mar/microbiología , Microbiología del Agua , Chrysophyta/clasificación , Chrysophyta/genética , Cilióforos/clasificación , Cilióforos/genética , Dermatoglifia del ADN , Epsilonproteobacteria/crecimiento & desarrollo , Epsilonproteobacteria/metabolismo , Océanos y Mares , Filogenia , Agua de Mar/química
5.
Arch Microbiol ; 194(9): 785-94, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22526267

RESUMEN

A novel chemolithoautotrophic hydrogen-oxidizing and sulfur-reducing bacterium, strain 496Chim(T), was isolated from a deep-sea hydrothermal vent chimney collected from the hydrothermal field at the summit of Nikko Seamount field, in the Mariana Arc. Cells were rods or curved rods, motile by means of a single polar flagellum. Growth was observed between 15 and 45 °C (optimum 37 °C; doubling time, 2.1 h) and between pH 5.3 and 8.0 (optimum pH 6.0). The isolate was a strictly anaerobic, obligate chemolithoautotroph capable of growth using molecular hydrogen as the sole energy source, carbon dioxide as the sole carbon source, ammonium or nitrate as the sole nitrogen source, and elemental sulfur as the electron acceptor. The G+C content of genomic DNA was 35 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the new isolate belonged to the class Epsilonproteobacteria, but the isolate was distantly related to the previously described Epsilonproteobacteria species potentially at the genus level (<90 %). On the basis of its physiological and molecular characteristics, strain 496Chim(T) (=DSM 22050(Τ) = JCM 15747(Τ) = NBRC 105224(Τ)) represents the sole species of a new genus, Thiofractor, for which the name Thiofractor thiocaminus is proposed.


Asunto(s)
Epsilonproteobacteria/clasificación , Epsilonproteobacteria/fisiología , Respiraderos Hidrotermales/microbiología , Composición de Base , Epsilonproteobacteria/aislamiento & purificación , Epsilonproteobacteria/ultraestructura , Concentración de Iones de Hidrógeno , Datos de Secuencia Molecular , Filogenia , Quinonas/metabolismo , ARN Ribosómico 16S/genética , Agua de Mar/microbiología , Especificidad de la Especie , Bacterias Reductoras del Azufre/clasificación , Bacterias Reductoras del Azufre/aislamiento & purificación , Bacterias Reductoras del Azufre/fisiología , Temperatura
6.
Nat Rev Microbiol ; 4(6): 458-68, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16652138

RESUMEN

The epsilon-proteobacteria have recently been recognized as globally ubiquitous in modern marine and terrestrial ecosystems, and have had a significant role in biogeochemical and geological processes throughout Earth's history. To place this newly expanded group, which consists mainly of uncultured representatives, in an evolutionary context, we present an overview of the taxonomic classification for the class, review ecological and metabolic data in key sulphidic habitats and consider the ecological and geological potential of the epsilon-proteobacteria in modern and ancient systems. These integrated perspectives provide a framework for future culture- and genomic-based studies.


Asunto(s)
Ambiente , Epsilonproteobacteria/fisiología , Azufre/metabolismo , Biodiversidad , Evolución Biológica , Carbono/metabolismo , Ecosistema , Epsilonproteobacteria/clasificación , Océanos y Mares , Filogenia
7.
Appl Environ Microbiol ; 74(3): 774-82, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18083873

RESUMEN

The equilibrium model, which describes the influence of temperature on enzyme activity, has been established as a valid and useful tool for characterizing enzyme eurythermalism and thermophily. By introducing K(eq), a temperature-dependent equilibrium constant for the interconversion between E(act), the active form of enzyme, and E(inact), a reversibly inactive form of enzyme, the equilibrium model currently provides the most complete description of the enzyme-temperature relationship; its derived parameters are intrinsic and apparently universal and, being derived under reaction conditions, potentially have physiological significance. One of these parameters, T(eq), correlates with host growth temperature better than enzyme stability does. The vent-dwelling annelid Alvinella pompejana has been reported as an extremely eurythermal organism, and the symbiotic complex microbial community associated with its dorsal surface is likely to experience similar environmental thermal conditions. The A. pompejana episymbiont community, predominantly composed of epsilonproteobacteria, has been analyzed metagenomically, enabling direct retrieval of genes coding for enzymes suitable for equilibrium model applications. Two such genes, coding for isopropylmalate dehydrogenase and glutamate dehydrogenase, have been isolated from the A. pompejana episymbionts, heterologously expressed, and shown by reverse transcription-quantitative PCR to be actively expressed. The equilibrium model parameters of characterized expression products suggested that enzyme eurythermalism constitutes part of the thermal adaptation strategy employed by the episymbionts. Moreover, the enzymes' thermal characteristics correspond to their predicted physiological roles and the abundance and expression of the corresponding genes. This paper demonstrates the use of the equilibrium model as part of a top-down metagenomic approach to studying temperature adaptation of uncultured organisms.


Asunto(s)
3-Isopropilmalato Deshidrogenasa/metabolismo , Adaptación Fisiológica , Anélidos/microbiología , Epsilonproteobacteria/enzimología , Epsilonproteobacteria/fisiología , Glutamato Deshidrogenasa/metabolismo , Simbiosis , Temperatura , 3-Isopropilmalato Deshidrogenasa/química , 3-Isopropilmalato Deshidrogenasa/genética , Animales , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biología Computacional , Epsilonproteobacteria/genética , Epsilonproteobacteria/crecimiento & desarrollo , Genómica , Glutamato Deshidrogenasa/química , Glutamato Deshidrogenasa/genética , Modelos Biológicos
8.
FEMS Immunol Med Microbiol ; 49(1): 101-23, 2007 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-17266717

RESUMEN

Campylobacter, Helicobacter and Wolinella are genera of the order Campylobacterales, belonging to the class Epsilonproteobacteria. Their habitats are various niches in the gastrointestinal tract of higher animals, where they may come into contact with bile. Microorganisms in these environments require mechanisms of resistance to the surface-active amphipathic molecules with potent antimicrobial activities present in bile. This review summarizes current knowledge on the molecular responses to bile by Campylobacterales and other bacterial species that inhabit the intestinal tract and belong to the phyla Proteobacteria, Bacteriodetes, Firmicutes and Actinobacteria. To date, 125 specific genes have been implicated in bile responses, of which 10 are found in Campylobacterales. Genome database searches, analyses of protein sequence and domain similarities, and gene ontology data integration were performed to compare the responses to bile of these bacteria. The results showed that 33 proteins of bacteria belonging to the four phyla had similarities equal to or greater than 50-46% proteins of Campylobacterales. Domain architecture analyses revealed that 151 Campylobacterales proteins had similar domain composition and organization to 60 proteins known to participate in the tolerance to bile in other bacteria. The proteins CmeB, CmeF and CbrR of Campylobacter jejuni involved in bile tolerance were homologous to 42 proteins identified in the Proteobacteria, Bacteriodetes and Firmicutes. On the other hand, the proteins CiaB, CmeA, CmeC, CmeD, CmeE and FlaAsigma(28) also involved in the response to bile of C. jejuni, did not have homologues in other bacteria. Among the bacteria inhabiting the gastrointestinal tract, the Campylobacterales seem to have evolved some mechanisms of bile resistance similar to those of other bacteria, as well as other mechanisms that appear to be characteristic of this order.


Asunto(s)
Bilis/fisiología , Epsilonproteobacteria/fisiología , Animales , Biología Computacional , Humanos
9.
ISME J ; 11(7): 1545-1558, 2017 07.
Artículo en Inglés | MEDLINE | ID: mdl-28375213

RESUMEN

At deep-sea hydrothermal vents, primary production is carried out by chemolithoautotrophic microorganisms, with the oxidation of reduced sulfur compounds being a major driver for microbial carbon fixation. Dense and highly diverse assemblies of sulfur-oxidizing bacteria (SOB) are observed, yet the principles of niche differentiation between the different SOB across geochemical gradients remain poorly understood. In this study niche differentiation of the key SOB was addressed by extensive sampling of active sulfidic vents at six different hydrothermal venting sites in the Manus Basin, off Papua New Guinea. We subjected 33 diffuse fluid and water column samples and 23 samples from surfaces of chimneys, rocks and fauna to a combined analysis of 16S rRNA gene sequences, metagenomes and real-time in situ measured geochemical parameters. We found Sulfurovum Epsilonproteobacteria mainly attached to surfaces exposed to diffuse venting, while the SUP05-clade dominated the bacterioplankton in highly diluted mixtures of vent fluids and seawater. We propose that the high diversity within Sulfurimonas- and Sulfurovum-related Epsilonproteobacteria observed in this study derives from the high variation of environmental parameters such as oxygen and sulfide concentrations across small spatial and temporal scales.


Asunto(s)
Epsilonproteobacteria/clasificación , Epsilonproteobacteria/fisiología , Respiraderos Hidrotermales/microbiología , Agua de Mar/microbiología , Azufre/metabolismo , Ciclo del Carbono , Microbiología Ambiental , Genoma Bacteriano , Metagenoma , Oxidación-Reducción , Óxidos , Filogenia , ARN Ribosómico 16S/genética , Azufre/química , Compuestos de Azufre
10.
FEMS Microbiol Lett ; 246(1): 75-9, 2005 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-15869964

RESUMEN

We report on the formation of conspicuous patterns by the sulfide-oxidizing bacterium Thiovulum majus and a recently described vibrioid bacterium. These microaerophilic bacteria form mucus veils on top of sulfidic marine sediment exhibiting regular spaced bacterial patterns (honeycombs, interwoven bands, or inverse honeycombs). A simple qualitative computer model, based on chemotaxis towards oxygen and the ability of the bacteria to induce water advection when attached, can explain the formation of the observed patterns. Our study shows that complex bacterial patterns in nature can be explained in terms of chemotaxis and resource optimisation without involvement of cell-cell signalling or social behavior amongst bacteria.


Asunto(s)
Fenómenos Fisiológicos Bacterianos , Quimiotaxis/fisiología , Simulación por Computador , Epsilonproteobacteria/fisiología , Sedimentos Geológicos/microbiología , Epsilonproteobacteria/crecimiento & desarrollo , Modelos Biológicos
11.
Curr Opin Microbiol ; 28: 115-21, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26590774

RESUMEN

The epsilon-proteobacteria are a widespread group of flagellated bacteria frequently associated with either animal digestive tracts or hydrothermal vents, with well-studied examples in the human pathogens of Helicobacter and Campylobacter genera. Flagellated motility is important to both pathogens and hydrothermal vent members, and a number of curious differences between the epsilon-proteobacterial and enteric bacterial motility paradigms make them worthy of further study. The epsilon-proteobacteria have evolved to swim at high speed and through viscous media that immobilize enterics, a phenotype that may be accounted for by the molecular architecture of the unusually large epsilon-proteobacterial flagellar motor. This review summarizes what is known about epsilon-proteobacterial motility and focuses on a number of recent discoveries that rationalize the differences with enteric flagellar motility.


Asunto(s)
Epsilonproteobacteria/fisiología , Flagelos/fisiología , Animales , Campylobacter/fisiología , ADN Bacteriano/genética , Epsilonproteobacteria/genética , Flagelos/ultraestructura , Tracto Gastrointestinal/microbiología , Humanos , Mucosa Intestinal/microbiología , Movimiento , Filogenia , ARN Ribosómico 16S/genética
12.
FEMS Microbiol Lett ; 362(14)2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26152701

RESUMEN

The genetic capacity to fix gaseous nitrogen (N) is distributed among diverse diazotrophs belonging to the Bacteria and Archaea. However, only a subset of the putative diazotrophs present actively fix N at any given time in the environment. We experimentally tested whether the availability of carbon and inhibition by oxygen constrain N fixation by diazotrophs in coastal seawater. The goal was to test whether by alleviating these constraints an increased overlap between nitrogenase (nifH)-gene-carrying and -expressing organisms could be achieved. We incubated water from a eutrophic but N-limited fjord in Denmark under high-carbon/low-oxygen conditions and determined bacterial growth and production, diazotrophic community composition (Illumina nifH amplicon sequencing), and nifH gene abundance and expression [quantitative PCR (qPCR) and quantitative reverse transcriptase PCR (qRT-PCR)]. Bacterial abundances and production increased under high-carbon/low-oxygen conditions as did the similarity between present and active diazotrophic communities. This was caused by the loss of specific abundant yet non-active gammaproteobacterial phylotypes and increased expression by others. The prominent active gamma- and epsilonproteobacterial diazotrophs did not, however, respond to these conditions in a uniform way, highlighting the difficulty to assess how a change in environmental conditions may affect a diverse indigenous diazotrophic community.


Asunto(s)
Bacterias/genética , Carbono/metabolismo , Estuarios , Consorcios Microbianos/fisiología , Fijación del Nitrógeno , Nitrogenasa/genética , Oxígeno/metabolismo , Plancton/genética , Epsilonproteobacteria/genética , Epsilonproteobacteria/fisiología , Gammaproteobacteria/genética , Gammaproteobacteria/fisiología , Oxidorreductasas/genética , Filogenia , Plancton/fisiología , Reacción en Cadena en Tiempo Real de la Polimerasa , Agua de Mar/microbiología
13.
Environ Toxicol Chem ; 22(11): 2614-21, 2003 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-14587900

RESUMEN

Technical toxaphene (Melipax) and the single compounds of technical toxaphene (CTTs) 2,2,5-endo,6-exo,8,8,9,10-octachlorobornane (B8-806), 2,2,5-endo,6-exo, 8,9,9,10-octachlorobornane (B8-809), 2,2,5,5,8,9,9,10,10-nonachlorobornane (B9-1025), 2-endo,3-exo,5-endo,6-exo,8,8,9,10,10-nonochlorobornane (B9-1679), 2-endo,3-exo,5-endo,6-exo,8,9,10,10-octachlorobornane (B8-1414), 2-endo,3-exo,5-endo,6-exo,8,8,9,10-octachlorobornane (B8-1412), and 2-exo,3-endo,5-exo,9,9,10,10-heptachlorobornane (B7-1453) were treated with suspensions of the anaerobic bacterium Dehalospirillum multivorans. After 7 d, more than 50% of technical toxaphene was transformed, and the relative amount of early eluting CTTs increased. After 16 d, only 2-exo,3-endo,6-exo, 8,9,10-hexachlorobornane (B6-923), 2-endo,3-exo,5-endo,6-exo, 8,9,10-heptachlorobornane (B7-1001), and a few minor penta- and hexachloro-CTTs were detected in the samples. The result of the transformation was comparable with observations in naturally contaminated sediments and soil. However, the performance with D. multivorans was more simple and reproducible, as well as faster, than use of soil, sediment, or anaerobic sewage sludge. In agreement with reports in the literature, reductive dechlorination at geminal chlorine atoms (gem-C1s) was found to be the major CTT transformation pathway. Experiments conducted with CTTs and gem-C1s at both primary and secondary carbons clarified that the initial C1 --> H substitution takes place at the secondary carbon C2. Furthermore, the 2-endo-C1 position was preferably substituted with hydrogen. In the case of B8-806, the dechlorination at the secondary carbon C2 was approximately 20-fold faster than the subsequent, slow reduction at the primary carbon C8. The three different formerly unknown heptachloro-CTTs, 2-exo,3-endo,6-exo,8,9,9,10-heptachlorobornane (B7-1473), 2-exo, 3-endo,6-endo,8,9,9,10-hepatchlorobornane (B7-1461), and 2-exo, 3-endo,6-exo,8,8,9,10-heptachlorobornane (B7-1470) were found as intermediates of the B8-806/809 transformation. Treatment of B9-1679 with D. multivorans indicated that gem-C1s on the bridge (C8 and C9) are dechlorinated faster than gem-C1s on the bridgehead (C10).


Asunto(s)
Canfanos/metabolismo , Epsilonproteobacteria/fisiología , Insecticidas/metabolismo , Toxafeno/metabolismo , Biotransformación , Cloro/química , Oxígeno
14.
ISME J ; 7(1): 96-109, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22914596

RESUMEN

The shrimp Rimicaris exoculata dominates several hydrothermal vent ecosystems of the Mid-Atlantic Ridge and is thought to be a primary consumer harbouring a chemoautotrophic bacterial community in its gill chamber. The aim of the present study was to test current hypotheses concerning the epibiont's chemoautotrophy, and the mutualistic character of this association. In-vivo experiments were carried out in a pressurised aquarium with isotope-labelled inorganic carbon (NaH(13)CO(3) and NaH(14)CO(3)) in the presence of two different electron donors (Na(2)S(2)O(3) and Fe(2+)) and with radiolabelled organic compounds ((14)C-acetate and (3)H-lysine) chosen as potential bacterial substrates and/or metabolic by-products in experiments mimicking transfer of small biomolecules from epibionts to host. The bacterial epibionts were found to assimilate inorganic carbon by chemoautotrophy, but many of them (thick filaments of epsilonproteobacteria) appeared versatile and able to switch between electron donors, including organic compounds (heterotrophic acetate and lysine uptake). At least some of them (thin filamentous gammaproteobacteria) also seem capable of internal energy storage that could supply chemosynthetic metabolism for hours under conditions of electron donor deprivation. As direct nutritional transfer from bacteria to host was detected, the association appears as true mutualism. Import of soluble bacterial products occurs by permeation across the gill chamber integument, rather than via the digestive tract. This first demonstration of such capabilities in a decapod crustacean supports the previously discarded hypothesis of transtegumental absorption of dissolved organic matter or carbon as a common nutritional pathway.


Asunto(s)
Ciclo del Carbono , Decápodos/microbiología , Epsilonproteobacteria/aislamiento & purificación , Gammaproteobacteria/aislamiento & purificación , Branquias/microbiología , Respiraderos Hidrotermales , Animales , Crecimiento Quimioautotrófico , Decápodos/fisiología , Epsilonproteobacteria/fisiología , Gammaproteobacteria/fisiología , Simbiosis
15.
Environ Microbiol Rep ; 5(2): 282-90, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23584970

RESUMEN

The Epsilonproteobacteria, including members of the genus Sulfurovum, are regarded as important primary producers in hydrothermal systems. However, their in situ gene expression in this habitat has so far not been investigated. We report a metatranscriptomic analysis of a Sulfurovum-dominated biofilm from one of the chimneys at the Loki's Castle hydrothermal system, located at the Arctic Mid Ocean Ridge. Transcripts involved in hydrogen oxidation, oxidation of sulfur species, aerobic respiration and denitrification were abundant and mostly assigned to Sulfurovum, indicating that members of this genus utilize multiple chemical energy sources simultaneously for primary production. Sulfurovum also seemed to have a diverse expression of transposases, potentially involved in horizontal gene transfer. Other transcripts were involved in CO2 fixation by the reverse TCA cycle, the CRISPR-Cas system, heavy metal resistance, and sensing and responding to changing environmental conditions. Through pyrosequencing of PCR amplified 16S rRNA genes, the Sulfurovum-dominated biofilm was compared with another biofilm from the same chimney, revealing a large shift in the community structure of Epsilonproteobacteria-dominated biofilms over a few metres.


Asunto(s)
Proteínas Bacterianas/genética , Biopelículas , Materiales de Construcción/microbiología , Epsilonproteobacteria/aislamiento & purificación , Epsilonproteobacteria/fisiología , Regulación Bacteriana de la Expresión Génica , Regiones Árticas , Proteínas Bacterianas/metabolismo , ADN Bacteriano/genética , Ecosistema , Epsilonproteobacteria/clasificación , Epsilonproteobacteria/genética , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética
16.
FEMS Microbiol Ecol ; 84(3): 625-39, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23398056

RESUMEN

Redox transition zones play a crucial role in biogeochemical cycles of several major elements. Because microorganisms mediate many reactions of these cycles, they actively participate in establishing geochemical gradients. In turn, the geochemical gradients structure microbial communities. We studied the interrelationship between the bacterial community structure and the geochemical gradient in the Cariaco Basin, the largest truly marine anoxic basin. This study's dataset includes bacterial community composition in 113 water column samples as well as the data for environmental variables (gradients of oxygen, hydrogen sulfide, sulfite, thiosulfate, ammonia, nitrate, nitrite, dissolved manganese and iron, dark CO2 fixation, and bacterial abundance) collected between 1997 and 2006. Several prominent bacterial groups are present throughout the entire water column. These include members of Gamma-, Delta-, and Epsilonproteobacteria, as well as members of the Marine Group A, the candidate divisions OP11 and Car731c. Canonical correspondence analysis indicated that microbial communities segregate along vectors representing oxygenated conditions, nitrite, nitrate and anoxic environments represented by chemoautotrophy, ammonia, sulfite, and hydrogen sulfide.


Asunto(s)
Bacterias/aislamiento & purificación , Agua de Mar/microbiología , Anaerobiosis , Bacterias/clasificación , Bacterias/genética , Bacterias Anaerobias/genética , Bacterias Anaerobias/aislamiento & purificación , Bacterias Anaerobias/fisiología , Dióxido de Carbono/análisis , Ecosistema , Epsilonproteobacteria/genética , Epsilonproteobacteria/aislamiento & purificación , Epsilonproteobacteria/fisiología , Sulfuro de Hidrógeno/análisis , Metagenoma , Nitratos/análisis , Nitritos/análisis , Oxígeno/análisis , Filogenia , Agua de Mar/química , Microbiología del Agua
17.
PLoS One ; 7(10): e46282, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-23056274

RESUMEN

In this study, we report experimental evidence of the thioautotrophic activity of the epibiotic microbial community associated with the setae of Shinkaia crosnieri, a galatheid crab that is endemic to deep-sea hydrothermal systems in the Okinawa Trough in Japan. Microbial consumption of reduced sulfur compounds under in situ hydrostatic and atmospheric pressure provided evidence of sulfur-oxidizing activity by the epibiotic microbial community; the rate of sulfur oxidation was similar under in situ and decompressed conditions. Results of the microbial consumption of reduced sulfur compounds and tracer experiments using (13)C-labeled bicarbonate in the presence and absence of thiosulfate (used as a thioautotrophic substrate) convincingly demonstrated that the epibiotic microbial community on S. crosnieri drove primary production via an energy metabolism that was coupled with the oxidation of reductive sulfur compounds. A combination of tracer experiments, fluorescence in situ hybridization (FISH) and nano-scale secondary ion mass spectrometry (Nano-SIMS) indicated that the filamentous cells of the genus Sulfurovum belonging to the class Epsilonproteobacteria were thioautotrophs in the epibiotic community of S. crosnieri. In conclusion, our results strongly suggest that thioautotrophic production by Sulfurovum members present as the epibiotic microbial community play a predominant role in a probable nutritional ectosymbiosis with S. crosnieri.


Asunto(s)
Crustáceos/microbiología , Epsilonproteobacteria/fisiología , Agua de Mar/microbiología , Animales , Epsilonproteobacteria/genética , Epsilonproteobacteria/metabolismo , Hibridación Fluorescente in Situ , Espectrometría de Masa de Ion Secundario , Azufre/metabolismo
18.
ISME J ; 6(3): 597-609, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21993397

RESUMEN

The caridean shrimp Rimicaris exoculata dominates the fauna at several Mid-Atlantic Ridge hydrothermal vent sites. This shrimp has an enlarged gill chamber, harboring a dense ectosymbiotic community of chemoautotrophic bacteria associated with mineral oxide deposits. Until now, their acquisition is not fully understood. At three hydrothermal vent sites, we analyzed the epibionts diversity at different moult stages and also in the first stages of the shrimp life (eggs, hatched eggs (with larvae) and juveniles). Hatched eggs associated with young larvae were collected for the first time directly from gravid females at the Logachev vent site during the Serpentine cruise. An approach using 16S rRNA clone libraries, scanning and transmission electron microscopy, and fluorescent in situ hybridization was used. Molecular results and microscope observations indicated a switch in the composition of the bacterial community between early R. exoculata life cycle stage (egg libraries dominated by the Gammaproteobacteria) and later stages (juvenile/adult libraries dominated by the Epsilonproteobacteria). We hypothesized that the epibiotic phylotype composition could vary according to the life stage of the shrimp. Our results confirmed the occurrence of a symbiosis with Gammaproteobacteria and Epsilonproteobacteria, but more complex than previously assumed. We revealed the presence of active type-I methanotrophic bacteria colonizing the cephalothorax of shrimps from the Rainbow site. They were also present on the eggs from the Logachev site. This could be the first 'epibiotic' association between methanotrophic bacteria and hydrothermal vent crustacean. We discuss possible transmission pathways for epibionts linked to the shrimp life cycle.


Asunto(s)
Decápodos/microbiología , Epsilonproteobacteria/fisiología , Gammaproteobacteria/fisiología , Simbiosis , Animales , ADN Bacteriano/genética , Decápodos/crecimiento & desarrollo , Epsilonproteobacteria/genética , Femenino , Gammaproteobacteria/genética , Branquias/microbiología , Respiraderos Hidrotermales , Hibridación Fluorescente in Situ , Estadios del Ciclo de Vida , Filogenia , ARN Ribosómico 16S/genética
19.
FEMS Microbiol Ecol ; 79(2): 421-32, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22092920

RESUMEN

Epsilonproteobacteria are widely distributed in marine, freshwater, and terrestrial environments, although most well-studied groups are from hydrothermal vents and the human intestinal tract. The environmental variables that control epsilonproteobacterial communities in sulfidic terrestrial environments, however, are poorly understood. Here, the environmental variables that influence epsilonproteobacterial community composition in geographically separated sulfidic caves and springs were determined by coarse and fine-scale approaches: denaturing gradient gel electrophoresis profiling of 23S rRNA PCR amplicons and clone library sequencing of the 16S-ITS-23S rRNA operon. Sequences retrieved from this study were not closely related to cultured representatives, indicating that existing culture collections do not adequately capture the diversity of terrestrial Epsilonproteobacteria. Comparisons of 16S-ITS-23S rRNA operon sequences from four sites revealed that some distant communities (> 8000 km) share closely related populations of Epsilonproteobacteria, while other sites have nearly clonal and phylogenetically distinct populations. Statistical evaluations of sequence data reveal that multiple environmental variables (e.g. temperature, pH, salinity, dissolved oxygen, and bicarbonate concentrations) influence Epsilonproteobacteria community composition. Locations with clonal populations tended to be from higher temperatures and intermediate dissolved oxygen concentrations. rRNA operon sequences outside of the 16S rRNA gene may be critical to recognizing environmental drivers of epsilonproteobacterial community composition.


Asunto(s)
Cuevas/microbiología , Epsilonproteobacteria/fisiología , Agua Dulce/microbiología , Secuencia de Bases , Cuevas/química , Epsilonproteobacteria/clasificación , Epsilonproteobacteria/genética , Agua Dulce/química , Genes de ARNr , Humanos , Respiraderos Hidrotermales , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa , ARN Ribosómico 23S , Azufre/análisis
20.
mBio ; 2(5)2011.
Artículo en Inglés | MEDLINE | ID: mdl-21933915

RESUMEN

For almost 50 years, Escherichia coli has been the model for understanding how bacteria orient their movement in response to chemical cues, but recent studies of chemotaxis in other bacteria have revealed interesting variations from prevailing paradigms. Investigating the human pathogen Helicobacter pylori, Amieva and colleagues [mBio 2(4):e00098-11, 2011] discovered a new chemotaxis regulator, ChePep, which modulates swimming behavior through the canonical histidine-aspartate phosphorelay system. Functionally conserved among the epsilonproteobacteria, ChePep is essential for H. pylori to navigate deep into the stomach's gastric glands and may be an attractive target for novel antibiotics.


Asunto(s)
Proteínas Bacterianas/metabolismo , Quimiotaxis , Epsilonproteobacteria/fisiología , Epsilonproteobacteria/patogenicidad , Mucosa Gástrica/microbiología , Factores de Virulencia/metabolismo , Animales , Femenino
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