Diversity of microbial communities in hot springs of Sri Lanka as revealed by 16S rRNA gene high-throughput sequencing analysis.

Characterization of hot spring microbiota is useful as an initial platform for exploring industrially important microbes. The present study focused on characterization of microbiota in four hot springs in Sri Lanka: Maha Oya; Wahava; Madunagala; and Kivlegama using high throughput 16S amplicon sequencing. Temperatures of the selected springs were ranged from 33.7 °C to 52.4 °C, whereas pH ranged from 7.2 to 8.2. Bacteria were found to be the dominant microbial group (>99%) compared to Archaea which represented less than 1% of microbiota. Four hot springs comprised of unique microbial community structures. Proteobacteria, Firmicutes, Bacteroidetes, Cloroflexi, Deinococcus and Actenobacteria were the major bacterial phyla. Moderately thermophilic genera such as Thermodesulfobacteria and Deinococcus-Thermus were detected as major genera that could be used in industrial applications operating at temperatures around 50 °C and alkaline reaction conditions.

COMPARISON OF THE RADIO-ISOTOPIC COMPOSITION BETWEEN HOT SPRING WATER OF HAMMAM DEBAGH AND ITS ASSOCIATED DEPOSITS.

A radiological analysis of hot spring water of Hammam Debagh (also called Hammam Meskhoutine) and its associated deposits was realized. Hammam Debagh is considered to be the second hottest springs in the world with a temperature of 98°C and this lead to the creation of travertine. This later was formed because of limestone deposited by mineral springs in a rapid sedimentation of calcium, magnesium bicarbonates, and sulphides. The analysis showed that two-thirds of radioactivity was left by spring water in their deposits. The presence of uranium in the spring deposits was due to the property of the uranyl ion to form stable complexes with carbonates and precipitates. The radiation hazards indexes were estimated and compared with those given in literature.

Assessing the Committed Effective Dose From 226Ra in Thermal Spring Water From San Diego De Alcala, Chihuahua, Mexico.

The oral administration of mineral-rich spring water is known as hydropinic treatment and is used to treat certain ailments. Health benefits are attributed to thermal spring water containing radioactive elements such as radium; this has popularized use of such radioactive water in various parts of the world, causing those who ingest it to increase their internal radiation dose. The goal of this study was to assess the activity concentrations of Ra present in the thermal spring waters of San Diego de Alcala, in the state of Chihuahua, Mexico, and to estimate the health risk posed to patients by the effective dose received from ingesting this water during hydropinic treatments. Water samples were taken from different areas of the San Diego de Alcala thermal springs, and pH, temperature, electrical conductivity, and total dissolved solids were measured. The Ra activity concentrations were measured with a liquid scintillation counter. The activity concentrations of Ra in sampled water varied from 125 to 452 mBq L with an average of 276 ± 40 mBq L. The committed effective dose from each of the Ra activity concentrations found in samples ranged from 9.80 × 10 to 4.0 × 10 mSv for hydropinic treatments being carried out in San Diego de Alcala thermal spring spas. Different treatments had different intake rates (200, 600, 1,000, and 1,500 mL d) and occurred over periods of 2 or 3 wk. According to the guidelines of the US Environmental Protection Agency, the maximum permissible amount of radium in drinking water is 185 mBq L; the Ra content in most of the collected samples exceeded this limit. The committed effective doses varied with Ra concentration and intake rate; none exceeded the World Health Organization's reference dose for drinking water of 0.1 mSv y, which is the maximum amount to which the population should be exposed.

Bacterial communities of the microbial mats of Chokrak sulfide springs.

This is the comparative investigation of the composition of phototrophic microbial mats developing in sulfide-rich saline Chokrak springs with outflow at the shore of the hypersaline lake Chokrak by means of next-generation sequencing. The springs are characterized by low temperature (~ 15 °C), near-neutral pH (6.7-8.5), and high-sulfide content. In the species composition the benthic microbial communities of Chokrak springs are similar to microbial mats of marine supralittoral and lagoons. Our results showed that salinity limitation had a significant effect on the species composition of benthic microbial communities developing at the outflow of the Chokrak springs. Predominant oxygenic phototrophs belonged to the genera Phormidium, Lyngbya, Leptolyngbya, Geitlerinema, and Arthrospira. Anoxygenic phototrophic bacteria were represented by halophilic green sulfur bacteria Prosthecochloris spp., halotolerant Chlorobaculum sp., as well as marine and extremely halophilic purple bacteria Roseospira, Rhodovibrio, and Halochromatium. Monoculture of a new species of halotolerant anoxygenic filamentous phototrophic bacteria was isolated.

Natural radioactivity of thermal springs and related precipitates in Gellért Hill area, Buda Thermal Karst, Hungary.

The elevated radioactivity of the thermal waters of Buda Thermal Karst (BTK), Hungary is known and studied since the beginning of the 20th century. In the recent studies, the anomalous 222Rn/226Ra ratios have drawn the attention to the existence of local 222Rn source. Biogeochemical precipitates (i.e. biofilms) in spring caves were found to have high adsorption capacity, accumulating e.g. 226Ra. Biogeochemical precipitates are ubiquitous in the thermal springs of BTK, occurring in different amount and colours (dark grey, brown, red, white), and have different microbial communities and elemental composition. The detailed investigation of the radioactivity of spring waters highlighted the different 226Ra and 222Rn activity concentrations. The present study aimed to survey the radioactivity of the thermal springs of Gellért Hill area, together with the biogeochemical precipitates and air above the water level, and to assess the evolution of the radioactivity of known-aged precipitates, formed during in situ experiments. We found that the basic physicochemical parameters of the spring waters (field parameters, major ions) do not affect the adsorption capacity of biogeochemical precipitates. It was revealed by the conducted in situ experiments, that the flow conditions influence the evolution rate of precipitates, so their adsorption capacity. The 222Rn activity concentrations of spring waters are dependent on the area of the water surface, volume of air space above the water level, ventilation of the caves/channels and presence of calcite layer on the water surface. The latter has a blocking effect on degassing.

Radon concentration in hydrogeothermal deposit and spas of Boyacá, Colombia.

Inhaled radon and its progenies induce health concern due to high activity-concentration in selected thermal spas of Boyacá region. Hydrogeothermal water sources in a high risk seismic area, are studied to determine by water bubbling method radon concentration values; their occurrence is between few hundreds and 2000 Bq dm-3. Deposits, existing in this area, reach at the surface soil gas radon concentration up to 210 kBq m-3. Maintenance workers, health tourists and visitor's possible detrimental health effects, are discussed in relation to radon balneotherapy beneficial aspects.

RADIONUCLIDE AND MAJOR ELEMENT ANALYSIS OF THERMAL AND MINERAL WATERS IN CROATIA WITH A RELATED DOSE ASSESSMENT.

Major elements concentrations (Na, K, Ca, Mg) and the activity concentrations of 226,228Ra, 234,238U, 210Po, 210Pb, 40K and 137Cs in northern and eastern Croatian thermal and mineral waters, collected directly from springs (or wells), are presented herein with total effective doses assessed for those waters that are considered as drinking 'cures' and are available for consumption. The methods used for radionuclide determination included alpha-particle spectrometry, gas-proportional counting and gamma-ray spectrometry, while the major element composition was determined by ICP-MS. The activity concentrations of all of the radionuclides were found to be below the guidance levels set by the WHO and EC Directive, with the exception of one water sample that measured 0.26 Bq L-1 of 228Ra. The effective ingestion dose assessment for the consumption of the so-called water 'cures' during 1, 2 or 4 weeks' time period throughout 1 year was well below the recommended 0.1 mSv for drinking water.

Study of isotopes of carbon, thorium, and uranium in travertine and thermal spring samples: implications for effects of changes in geochemical environment and processes.

Data on modern radiocarbon activity in the old travertine formations of the Pymvashor hydrothermal system were used, in combination with 230Th/U dating of the travertine, to estimate the 14C contents of the total dissolved inorganic carbon in the ancient thermal water at the time of precipitation of the travertine (14Ccalc). With the known values of 14Ccalc and average age of the thermal water, and under the assumption that the residence time of the water in aquifer was constant over the last 13.9 ± 1.5 ka, the initial 14C contents (14C0) in the ancient thermal water were estimated. The findings in this study are that (1) both 14C0 and δ13С have decreased in young waters compared to the ancient waters; (2) although atmospheric 14C activity (14Catm) has also decreased in the same time, the decrease in 14C0 is faster than the decrease in 14Catm. Under certain assumptions, one could link changes in 14C0 and δ13C to climate change. Decrease in δ13С of soil CO2 and decrease in 14C0 was caused predominantly by warmer and wetter climate, decomposition of fossil organic matter, and decrease in 14Catm. There could be also increased dissolution of solid carbonate and increased carbon exchange between DIC and soil CO2, caused by thawing permafrost.

Isolation of highly thermostable ß-xylosidases from a hot spring soil microbial community using a metagenomic approach.

The DNA extracted from a high-temperature environment in which micro-organisms are living will be a good source for the isolation of thermostable enzymes. Using a metagenomic approach, we aimed to isolate thermostable ß-xylosidases that will be exploited for biofuel production from lignocellulosic biomass. DNA samples obtained from the soil near a spout of a hot spring (70°C, pH7.2) were subjected to sequencing, which generated a total of 84.2 Gbp with 967,925 contigs of >500 bp in length. Similarity search for ß-xylosidase in the contigs revealed the presence of 168 candidate sequences, each of which may have arisen from more than one gene. Individual genes were amplified by PCR using sequence-specific primers. The resultant DNA fragments were cloned and introduced into Escherichia coli BL21 Star(DE3). Consequently, 269 proteins were successfully expressed in the E. coli cells and then examined for ß-xylosidase activity. A total of 82 proteins exhibited ß-xylosidase activity at 50°C, six of which retained the activity even at 90°C. Out of the six, three proteins were originated from a single candidate sequence, AR19M-311. An amino acid sequence comparison suggested the amino acid residues that appeared to be crucial for thermal stability of the enzymes.

Oxygenic and anoxygenic photosynthesis in a microbial mat from an anoxic and sulfidic spring.

Oxygenic and anoxygenic photosynthesis were studied with microsensors in microbial mats found at 9-10 m depth in anoxic and sulfidic water in Little Salt Spring (Florida, USA). The lake sediments were covered with a 1-2 mm thick red mat dominated by filamentous Cyanobacteria, below which Green Sulfur Bacteria (GSB, Chlorobiaceae) were highly abundant. Within 4 mm inside the mats, the incident radiation was attenuated to undetectable levels. In situ microsensor data showed both oxygenic photosynthesis in the red surface layer and light-induced sulfide dynamics up to 1 cm depth. Anoxygenic photosynthesis occurred during all daylight hours, with complete sulfide depletion around midday. Oxygenic photosynthesis was limited to 4 h per day, due to sulfide inhibition in the early morning and late afternoon. Laboratory measurements on retrieved samples showed that oxygenic photosynthesis was fully but reversibly inhibited by sulfide. In patches Fe(III) alleviated the inhibition of oxygenic photosynthesis by sulfide. GSB were resistant to oxygen and showed a low affinity to sulfide. Their light response showed saturation at very low intensities.

hsp90 and hsp47 appear to play an important role in minnow Puntius sophore for surviving in the hot spring run-off aquatic ecosystem.

Changes in the expression of a number of hsp genes in minnow Puntius sophore collected from a hot spring run-off (Atri hot spring in Odisha, India; 20o09'N 85°18'E, 36-38 °C) were investigated to study the upper thermal acclimation response under heat stress, using same species from aquaculture ponds (water temperature 27 °C) as control. Expression of hsp genes was analyzed in both groups using RT-qPCR, which showed up-regulation of hsp90 (2.1-fold) and hsp47 (2.5-fold) in hot spring run-off fishes, whereas there was no alteration in expression of other hsps. As the fish inhabit the hot spring run-off area for very long duration, they could have adapted to the environment. To test this hypothesis, fishes collected from hot spring run-off were divided into two groups; one was heat-shocked at 41 °C/24 h, and the other was acclimatized at 27 °C/24 h. Up-regulation of all the hsps (except hsp78) was observed in the heat-shocked fishes, whereas expression of all hsps was found to be down-regulated to the basal level in fishes maintained at 27 °C/24 h. Pathway analysis showed that the expressions of all the hsps except hsp90 are regulated by the transcription factor heat shock factor 1 (Hsf1). This study showed that hsp90 and hsp47 play an important role in Puntius sophore for surviving in the high-temperature environment of the hot spring run-off. Additionally, we show that plasticity in hsp gene expression is not lost in the hot spring run-off population.

Balneario de San Nicolás de Alhama (Almería). Historia y generalidades / The San Nicolás de Alhama's Spa (Almería). History and generalities

Se hace una reseña de la situación geográfica del Balneario de San Nicolás, de los antecedentes históricos del mismo y situación actual, así como de sus aguas minero‐medicinales, sus propietarios, el primer análisis realizado por un farmacéutico, la dirección médica y los pacientes que le han frecuentado (AU)

An a ccount of the geographical position of Alhama de Almería'Spa is given, including a brief history of it and its situation nowdays. An particularly reference it is made about the minero‐medicinal waters of this Spa, their proprietaries, the pharmacist who made the first chemical analysis, the sanitary direction and the patients frequented it (AU)

Análisis de la radiactividad en aguas del Balneario de San Nicolás (Almería) / Radioactivity analysis of San Nicolás Spa water

Se ha realizado el estudio radiológico del agua del manantial del Balneario de San Nicolás en la provincia de Almería. Este estudio ha consistido en la determinación cuantitativa de los radionucleidos naturales más importantes desde el punto de vista de la protección radiológica existentes en las aguas del balneario. La medida del contenido radiactivo de las aguas constituye un tema cuyo estudio resulta de gran interés. Las aguas con elementos radiactivos disueltos pueden producir, como consecuencia directa de su consumo, dosis de irradiación interna tanto por ingestión como por inhalación de estos elementos. Debido a esto es necesario, en algunos casos, proceder al análisis y posterior evaluación de la dosis asociada a este consumo (AU)

Radio activity analysis of San Nicolás Spa water was carried out by the CIEMAT Laboratory of Environmental Radioactivity. With this aim the most important natural radionuclides were determined in water from spring water. The measurement and knowledge of radioactivity level in water is an interesting and convenient topic. The consumption of water which has dissolved some radionuclides could lead to internal irradiation both by ingestion and by inhalation. Therefore it is necessary, in some cases, to determine the water radioactivity level in order to assess the dose (AU)

Microbiología del agua mineromedicinal del Balneario de San Nicolás / Microbiology of the natural mineral water of San Nicolás Spa

Se han estudiado los microorganismos autóctonos y alóctonos de las aguas mineromedicinales del Balneario San Nicolás (Alhama de Almería). No se han encontrado bacterias patógenas ni indicadores fecales en 250 mL de agua. La microbiota autóctona está constituida, principalmente, por bacterias oligotrofas Gram positivas de la clase Firmicutes. El sondeo Sillero, utilizado en los tratamientos, presenta un número muy bajo de bacterias viables (<10 ufc/mL) que corresponden en su mayoría a cocos Gram positivos (93,3%) y a la especie Staphylococcus lugdunensis (40%). El sondeo San Marcos tiene una mayor diversidad microbiana, predominando los bacilos Gram positivos de la especie Bacillus licheniformis (32,4%) y los bacilos Gram negativos de la especie Cupriavidus pauculus (16,2%). En todas las muestras se han detectado microorganismos proteolíticos, amilolíticos, nitrificantes y amonificantes, así como bacterias halófilas y del hierro. También se han estudiado los biotapetes formados en las fuentes utilizadas para bebida, constituidos por una asociación de cianobacterias filamentosas y esféricas, así como del alga Cosmarium (AU)

Both the autochthonous and the allochthonous microorganisms of minero‐medicinal water from the San Nicolas spa (Alhama of Almería, Spain) have been analyzed. No pathogen bacteria or faecal indicators have been found in 250 mL of water. The autochthonous microbiota is mainly composed of oligotrophic Grampositive bacteria of the Firmicutes phylum. The Sillero sampling, used in the spa treatments, presents a very low count of viable bacteria (< 10 cfu / mL), being the most part of them Grampositive cocci (93.3%) of the Staphylococcus lugdunensis (40%) species. The San Marcos sampling presents a higher microbial diversity, predominantly Gram‐positive bacilli of the Bacillus licheniformis (32.4%) species and Gram‐negative bacilli of the Cupriavidus pauculus (16.2%) species. Proteolytic, amylolitic, nitrifying and ammonifying microorganisms have been detected in all samples, altogether with halophilic and iron bacteria. An analysis of the microbial mats growing in the spa drinking water sources shows that these consist of an association of spherical and filamentous cyanobacteria and the Cosmarium algae (AU)

Climatología del Balneario de San Nicolás / Climatology of San Nicolás Spa

En el presente trabajo se realiza un estudio climático y bioclimático del Balneario de San Nicolás, ubicado en c. Para llevar a cabo este estudio se han utilizado datos de precipitación, temperatura, humedad relativa y viento, que se han obtenido de las estaciones de AEMET ubicadas en torno a Alhama de Almería, en concreto se han utilizado datos de la estación termo‐pluviométrica de Alhama y de la estación completa de Almería/aeropuerto. Se han obtenido los valores medios mensuales para cada uno de los parámetros climáticos relevantes, así como los valores extremos, la frecuencia de superación de determinados umbrales, las tendencias a largo plazo y los valores de determinados índices climáticos. Para el análisis bioclimático se han utilizado los datos de temperatura y humedad relativa y se han calculado los índices climatológicos de confort y de sensación térmica (AU)

A climatic and bioclimatic study of the spa located in Alhama de Almería (Almería) village is described in this paper. The climatological analysis has been performed using the data of precipitation, temperature, relative humidity and wind corresponding to the climatological stations of AEMET located near the village of Alhama of Almeria in particular the climatological station of Alhama and the principal station of Almería/airport. The monthly mean value and the extreme values have been obtained from the available data, as well as the frequency of climatic parameters exceeding certain thresholds, the long term trends and a set of climatic indices. For the bioclimatic analysis the data of temperature and relative humidity have been used to calculate the climatic comfort indices and the thermal sensation values (AU)

Estudio de los suelos del entorno del Balneario de San Nicolás (Almería) / Study soil in the thermal environment of San Nicolás (Almería)

Las propiedades fisico‐químicas de los suelos que se encuentran en la parte superficial de las capas freáticas, juegan un papel muy importante en las características hidroquímicas de las aguas subyacentes, pues fenómenos como disolución, hidrolisis y procesos de oxido‐reducción de fracciones minerales y orgánicas de los suelos influyen de forma significativa en la composición de las mismas. Además, textura, estructura y materia orgánica del suelo son factores claves en la regulación del régimen hidrodinámico. En este trabajo analizamos las características edáficas de cuatro suelos muy significativos de los alrededores del Balneario de San Nicolás, ubicado en Alhama de Almería, Alpujarra Almeriense, situada a 450 msnm en la ladera norte de la Sierra de Gádor. Son suelos con escaso desarrollo, tipo AC, formados a partir de materiales sedimentarios constituidos por margas arenosas, calcarenitas, dolomías y yeso, los situados en las proximidades del Valle del Andarax, y por materiales de derrubios de ladera y pie de monte, con predominio de cuarcita, dolomías, calizas y calizas margosas, los situados en la Sierra de Gádor. Los suelos son carbonatados y están saturados, siendo el calcio el catión mayoritario. Presentan pHs básicos, bajo contenido en materia orgánica y texturas gruesas. Cuarzo, calcita, dolomita y yeso son los minerales más abundantes entre los no laminares, y son las micas los filosilicatos presentes en mayor proporción. El predominio de texturas gruesas y la perdida de estructura en los horizontes profundos son determinantes en el grado de infiltración. Se han incluido en las unidades Regosoles y Calcisoles (AU)

The physico‐chemical properties of soils adjacent to aquifers play an essential role in the hydrochemical characteristics of the underlying waters. Thus, phenomena such as dissolution, hydrolysis and oxide‐reduction processes of the mineral and organic fractions of soils may have a significant influence on the composition of these waters. Furthermore, soil texture, structure and organic matter are key factors regulating the hydrodynamic regime. In this work, the edaphic characteristics of four highly representative soils located in the thermal environment of San Nicolas in the Alhama de Almería municipality of the Alpujarra Almeriense region were analyzed. The area is part of the northern side of the Sierra de Gádor at an altitude of 450 masl. They are poorly developed soils, mainly AC profiles. Soils in the vicinity of the Andarax Valley are formed on sedimentary materials constituted by sandy marls, calcarenites, dolomites and gypsum, and those in the Sierra de Gádor developed on debris material from hillside and piedmont and mainly integrated by quartzite, dolomites, limestones and marly limestones. Soils are carbonated and saturated, with calcium being the major cation. They have basic pH values, low organic matter content and coarse textures. Quartz, calcite, dolomite and gypsum are the prominent minerals among the non‐laminar ones, and micas among the phyllosilicates. The predominance of coarse textures and the loss of structure in the deep horizons are decisive in their infiltration capacity. They were classified as Regosols and Calcisols (AU)

Vegetación del entorno del Balneario de San Nicolás / The vegetation of San Nicolás spa environment

Se presenta una síntesis de la caracterización del entorno geográfico y de la vegetación natural del Balneario de San Nicolás, localizado en Alhama de Almería (Almería, Andalucía). Esta población, de ubicación privilegiada, domina la rambla del río Andarax y resulta un magnífico acceso para la exploración del entorno del conjunto montañoso de la Sierra de Gádor; además, la localidad, es una de las vías de acceso a las Alpujarras tanto almerienses como granadinas. A pesar del uso intensivo del territorio desde tiempos prehistóricos, el entorno de la Sierra de Gádor aún conserva importantes valores ecológicos y naturalísticos (AU)

A synthesis of the environmental characterization and natural vegetation of the geographic area of the San Nicolás spa, placed in Alhama de Almería (Almería, Andalusia), are presented. This village shows a privileged location on the upper part of the Andarax river canyon, having a wonderful access to explore the mountain environments of the Sierra de Gádor; moreover, the village is also a natural door to visit the Alpujarras natural region, in both Almería and Granada territories. Despite the intensive landscape human use since prehistorical times, some remarkable ecological and naturalistic features preserved at Sierra de Gádor deserve to be protected (AU)

Acción terapéutica de las aguas del Balneario de San Nicolás, Alhama de Almería / Therapeutic action of the waters of San Nicolás Spa, Alhama de Almería

Se hace referencia a las vicisitudes por las que atravesó el balneario de Alhama de Almería a lo largo del tiempo y se destaca la intervención de algunos médicos‐directores del balneario que ayudaron a mantenerlo activo. Las aguas mineromedicinales fueron declaradas de Utilidad Pública en 1884y ratificada esta declaración de Utilidad Pública por el Real Decreto 743/1928. Según recientes análisis, las aguas son hipertermales, de mineralización media, bicarbonatadas, sulfatadas, cálcicas, magnésicas, extremadamente duras y radiactivas. Se especifican, en este resumen, las vías de administración, técnicas utilizadas y los efectos que de ellas se derivan, destacando la balneo‐cinesiterapiay se señalan las indicaciones y contraindicaciones. Se analiza la información, aportada por la Dirección del balneario, referente a la población asistente en los últimos cinco años, su procedencia, número, género, así como las patologías más frecuentes y se muestran en forma de gráficos (AU)

This article make reference to the vicisitudes along the years the Alhama de Granada Spa went across, highlighthing the medical‐doctors supervision to maintain active the Spa. The mineral‐medicinal waters of this spa were declared of Public Utility in 1884 and ratified this declination by Real Decree 743/1928. According to recent analysis, these waters are hyperthermal, medium mineralization; bicarbonate, sulphate, calcium and magnesium being the predominant ions; extremely hard and radioactive. The routes of administration, techniques used and the effects arising from them are specified, highlighting the hydro‐kinesitherapy, as well as the indications and contraindications. Supplied information concerning to the population attending the spaduring the last five years, is analyzed; number and gender of the users, as well as the most frequent pathologies which are shown in some graphics (AU)

Hydrothermal gases in a shallow aquifer at Mt. Amiata, Italy: insights from stable isotopes and geochemical modelling.

We investigate the interaction between hydrothermal gases and groundwater in a major aquifer exploited for potable supply in the geothermal-volcanic area of Mt. Amiata, Central Italy. Two springs and two wells located on different sides of the volcanic edifice have been repeatedly sampled over the last 11 years. More than 160 chemical analyses and 10 isotopic analyses of total dissolved carbon (δ(13)C - total dissolved inorganic carbon (TDIC) = -15.9 to -7.8 ‰ vs. V-PDB) and sulphate (δ(34)S-SO4 = -6.9 to 5.1 ‰ vs. V-CDT) have been processed with geochemical modelling techniques. Best-fitting conditions between analytical data and model outputs have been achieved by numerical optimization, allowing for a quantitative description of gas-water-rock interactions occurring in this aquifer. Numerical calculations support a conceptual model that considers water-rock interactions to occur in the volcanic aquifer after inflow of deep-seated gases (CO2(g) and H2S(g)), and total conversion of H2S(g) to SO4, in the absence of mixing with geothermal waters from reservoirs currently exploited for electricity generation.

Ecophysiology of an uncultivated lineage of Aigarchaeota from an oxic, hot spring filamentous 'streamer' community.

The candidate archaeal phylum 'Aigarchaeota' contains microorganisms from terrestrial and subsurface geothermal ecosystems. The phylogeny and metabolic potential of Aigarchaeota has been deduced from several recent single-cell amplified genomes; however, a detailed description of their metabolic potential and in situ transcriptional activity is absent. Here, we report a comprehensive metatranscriptome-based reconstruction of the in situ metabolism of Aigarchaeota in an oxic, hot spring filamentous 'streamer' community. Fluorescence in situ hybridization showed that these newly discovered Aigarchaeota are filamentous, which is consistent with the presence and transcription of an actin-encoding gene. Aigarchaeota filaments are intricately associated with other community members, which include both bacteria (for example, filamentous Thermocrinis spp.) and archaea. Metabolic reconstruction of genomic and metatranscriptomic data suggests that this aigarchaeon is an aerobic, chemoorganoheterotroph with autotrophic potential. A heme copper oxidase complex was identified in the environmental genome assembly and highly transcribed in situ. Potential electron donors include acetate, fatty acids, amino acids, sugars and aromatic compounds, which may originate from extracellular polymeric substances produced by other microorganisms shown to exist in close proximity and/or autochthonous dissolved organic carbon (OC). Transcripts related to genes specific to each of these potential electron donors were identified, indicating that this aigarchaeon likely utilizes several OC substrates. Characterized members of this lineage cannot synthesize heme, and other cofactors and vitamins de novo, which suggests auxotrophy. We propose the name Candidatus 'Calditenuis aerorheumensis' for this aigarchaeon, which describes its filamentous morphology and its primary electron acceptor, oxygen.