Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

Article Types

Countries / Regions

Search Results (25)

Search Parameters:
Keywords = chemolithotroph

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
15 pages, 2643 KiB  
Article
Hot Mineral Water as a Medium for Molecular Hydrogen Reactions in the Primordial Hydrosphere for the Origin of Life
by Ignat Ignatov, Teodora P. Popova, Paunka Vassileva, Yordan G. Marinov and Mario T. Iliev
Hydrogen 2025, 6(3), 48; https://doi.org/10.3390/hydrogen6030048 - 15 Jul 2025
Viewed by 1423
Abstract
Studies have been conducted on the potential development of Hydrogenobacter thermophilus and Pseudomonas aeruginosa in an anaerobic environment, both in the presence and absence of molecular hydrogen (H2). H. thermophilus developed better at 70 °C and pH 7.0 in the presence [...] Read more.
Studies have been conducted on the potential development of Hydrogenobacter thermophilus and Pseudomonas aeruginosa in an anaerobic environment, both in the presence and absence of molecular hydrogen (H2). H. thermophilus developed better at 70 °C and pH 7.0 in the presence of molecular hydrogen. It also multiplied in its absence, but to a lesser extent. Dissolved hydrogen in an amount of 1 ppm is biologically active for this thermophilic chemolithotrophic species. The tested strains of P. aeruginosa also showed growth under anaerobic conditions in the presence of H2 concentrations of 1 ppm and 2 ppm, which was ensured by adding Mg. The results indicate that not only the oldest microorganisms on our planet, archaebacteria, but also current species such as H. thermophilus and P. aeruginosa are capable of development under conditions characteristic of the ancient hydrosphere. DFT analyses showed that hydrogen water forms stable water clusters, whose hydrogen bond network retains and stabilizes reducing agents such as molecular hydrogen and magnesium (Mg0). This creates a microenvironment in which key redox processes associated with autotrophic growth and chemical evolution can occur. This is a realistic model of the Earth’s primordial hydrosphere’s conditions. Full article
Show Figures

Graphical abstract

20 pages, 9495 KiB  
Article
Dominance of Sulfur-Oxidizing Bacteria, Thiomicrorhabdus, in the Waters Affected by a Shallow-Sea Hydrothermal Plume
by Chih-Ching Chung, Gwo-Ching Gong, Hsiao-Chun Tseng, Wen-Chen Chou and Chuan-Hsin Ho
Biology 2025, 14(1), 28; https://doi.org/10.3390/biology14010028 - 1 Jan 2025
Viewed by 1280
Abstract
The shallow-sea hydrothermal vent at Guishan Islet, located off the coast of Taiwan, serves as a remarkable natural site for studying microbial ecology in extreme environments. In April 2019, we investigated the composition of prokaryotic picoplankton communities, their gene expression profiles, and the [...] Read more.
The shallow-sea hydrothermal vent at Guishan Islet, located off the coast of Taiwan, serves as a remarkable natural site for studying microbial ecology in extreme environments. In April 2019, we investigated the composition of prokaryotic picoplankton communities, their gene expression profiles, and the dissolved inorganic carbon uptake efficiency. Our results revealed that the chemolithotrophs Thiomicrorhabdus spp. contributed to the majority of primary production in the waters affected by the hydrothermal vent plume. The metatranscriptomic analysis aligned with the primary productivity measurements, indicating the significant gene upregulations associated with carboxysome-mediated carbon fixation in Thiomicrorhabdus. Synechococcus and Prochlorococcus served as the prokaryotic photoautotrophs for primary productivity in the waters with lower influence from hydrothermal vent emissions. Thiomicrorhabdus and picocyanobacteria jointly provided organic carbon for sustaining the shallow-sea hydrothermal vent ecosystem. In addition to the carbon fixation, the upregulation of genes involved in the SOX (sulfur-oxidizing) pathway, and the dissimilatory sulfate reduction indicated that energy generation and detoxification co-occurred in Thiomicrorhabdus. This study improved our understanding of the impacts of shallow-sea hydrothermal vents on the operation of marine ecosystems and biogeochemical cycles. Full article
(This article belongs to the Special Issue Multi-Omics of Extremophilic Organisms)
Show Figures

Figure 1

15 pages, 2281 KiB  
Article
Exploration of In Vitro Voltage Production by a Consortium of Chemolithotrophic Microorganisms Using Galena (PbS) as a Sulphur Source
by Susana Citlaly Gaucin Gutiérrez, Juan Antonio Rojas-Contreras, David Enrique Zazueta-Álvarez, Efren Delgado, Perla Guadalupe Vázquez Ortega, Hiram Medrano Roldán and Damián Reyes Jáquez
Clean Technol. 2024, 6(1), 62-76; https://doi.org/10.3390/cleantechnol6010005 - 3 Jan 2024
Viewed by 2485
Abstract
Sulphur plays a fundamental role in the biological processes of chemolithotrophic microorganisms. Due to the redox characteristics of sulphur, microorganisms use it for metabolic processes. Such is the case of the dissimilatory processes in the anaerobic respiration of reducing microorganisms. The production of [...] Read more.
Sulphur plays a fundamental role in the biological processes of chemolithotrophic microorganisms. Due to the redox characteristics of sulphur, microorganisms use it for metabolic processes. Such is the case of the dissimilatory processes in the anaerobic respiration of reducing microorganisms. The production of electrical energy from the metabolism of native microorganisms using sulphur as substrate from inorganic mineral sources in the form of Galena (PbS) was achieved using MR mineral medium with 15% (w/v) of PbS mineral concentrate. At 400 h of growth, the highest voltage produced in an experimental unit under anaerobic conditions was 644 mV. The inoculum was composed of microorganisms with spiral morphology, and at the final stages of energy production, the only microorganism identified was Bacillus clausii. This microorganism has not been reported in bioelectrochemical systems, but it has been reported to be present in corrosive environments and reducing anoxic environments. Full article
(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)
Show Figures

Figure 1

20 pages, 2495 KiB  
Article
Microbial Ecosystems in Movile Cave: An Environment of Extreme Life
by Joost W. Aerts, Serban M. Sarbu, Traian Brad, Pascale Ehrenfreund and Hans V. Westerhoff
Life 2023, 13(11), 2120; https://doi.org/10.3390/life13112120 - 26 Oct 2023
Cited by 3 | Viewed by 2719
Abstract
Movile Cave, situated in Romania close to the Black Sea, constitutes a distinct and challenging environment for life. Its partially submerged ecosystem depends on chemolithotrophic processes for its energetics, which are fed by a continuous hypogenic inflow of mesothermal waters rich in reduced [...] Read more.
Movile Cave, situated in Romania close to the Black Sea, constitutes a distinct and challenging environment for life. Its partially submerged ecosystem depends on chemolithotrophic processes for its energetics, which are fed by a continuous hypogenic inflow of mesothermal waters rich in reduced chemicals such as hydrogen sulfide and methane. We sampled a variety of cave sublocations over the course of three years. Furthermore, in a microcosm experiment, minerals were incubated in the cave waters for one year. Both endemic cave samples and extracts from the minerals were subjected to 16S rRNA amplicon sequencing. The sequence data show specific community profiles in the different subenvironments, indicating that specialized prokaryotic communities inhabit the different zones in the cave. Already after one year, the different incubated minerals had been colonized by specific microbial communities, indicating that microbes in Movile Cave can adapt in a relatively short timescale to environmental opportunities in terms of energy and nutrients. Life can thrive, diversify and adapt in remote and isolated subterranean environments such as Movile Cave. Full article
Show Figures

Figure 1

13 pages, 1448 KiB  
Article
Autotrophic Production of the Sesquiterpene α-Humulene with Cupriavidus necator in a Controlled Bioreactor
by Anne Sydow, Lucas Becker, Eric Lombard, Roland Ulber, Stephane E. Guillouet and Dirk Holtmann
Bioengineering 2023, 10(10), 1194; https://doi.org/10.3390/bioengineering10101194 - 14 Oct 2023
Cited by 8 | Viewed by 2662
Abstract
Cupriavidus necator is a facultative chemolithotrophic organism that grows under both heterotrophic and autotrophic conditions. It is becoming increasingly important due to its ability to convert CO2 into industrially valuable chemicals. To translate the potential of C. necator into technical applications, it [...] Read more.
Cupriavidus necator is a facultative chemolithotrophic organism that grows under both heterotrophic and autotrophic conditions. It is becoming increasingly important due to its ability to convert CO2 into industrially valuable chemicals. To translate the potential of C. necator into technical applications, it is necessary to optimize and scale up production processes. A previous proof-of-principle study showed that C. necator can be used for the de novo production of the terpene α-humulene from CO2 up to concentrations of 11 mg L−1 in septum flasks. However, an increase in final product titer and space–time yield will be necessary to establish an economically viable industrial process. To ensure optimized growth and production conditions, the application of an improved process design in a gas bioreactor with the control of pH, dissolved oxygen and temperature including a controlled gas supply was investigated. In the controlled gas bioreactor, the concentration of α-humulene was improved by a factor of 6.6 and the space–time yield was improved by a factor of 13.2. These results represent an important step toward the autotrophic production of high-value chemicals from CO2. In addition, the in situ product removal of α-humulene was investigated and important indications of the critical logP value were obtained, which was in the range of 3.0–4.2. Full article
(This article belongs to the Section Biochemical Engineering)
Show Figures

Figure 1

19 pages, 2780 KiB  
Article
Automatic Control of Chemolithotrophic Cultivation of Cupriavidus necator: Optimization of Oxygen Supply for Enhanced Bioplastic Production
by Vera Lambauer, Alexander Permann, Zdeněk Petrášek, Vanja Subotić, Christoph Hochenauer, Regina Kratzer and Markus Reichhartinger
Fermentation 2023, 9(7), 619; https://doi.org/10.3390/fermentation9070619 - 29 Jun 2023
Cited by 17 | Viewed by 4619
Abstract
Gas fermentation is an upcoming technology to convert gaseous substrates into value-added products using autotrophic microorganisms. The hydrogen-oxidizing bacteria Cupriavidus necator efficiently uses CO2 as its sole carbon source, H2 as electron donor and O2 as electron acceptor. Surplus CO [...] Read more.
Gas fermentation is an upcoming technology to convert gaseous substrates into value-added products using autotrophic microorganisms. The hydrogen-oxidizing bacteria Cupriavidus necator efficiently uses CO2 as its sole carbon source, H2 as electron donor and O2 as electron acceptor. Surplus CO2 is stored in microbial storage material poly-(R)-3-hydroxybutyrate. O2 supply is the most critical parameter for growth and poly-(R)-3-hydroxybutyrate formation. A narrow O2 optimum between ~0.2 and ~4 mg/L was previously reported. Here, a standard benchtop bioreactor was redesigned for autotrophic growth of C. necator on explosive mixtures of CO2, H2 and O2. The bioreactor was equipped with mass flow control units and O2 and CO2 sensors. A controller for automated gas dosage based on a mathematical model including gas mass transfer, gas consumption and sensor response time was developed. Dissolved O2 concentrations were adjusted with high precision to 1, 2 and 4% O2 saturation (0.4, 0.8 and 1.5 mg/L dissolved O2, respectively). In total, up to 15 g/L cell dry weight were produced. Residual biomass formation was 3.6 ± 0.2 g/L under all three O2 concentrations. However, poly-(R)-3-hydroxybutyrate content was 71, 77 and 58% of the cell dry weight with 1, 2 and 4% dissolved O2, respectively. Full article
Show Figures

Figure 1

18 pages, 3212 KiB  
Article
The Genome of Varunaivibrio sulfuroxidans Strain TC8T, a Metabolically Versatile Alphaproteobacterium from the Tor Caldara Gas Vents in the Tyrrhenian Sea
by Sushmita Patwardhan, Jonathan Phan, Francesco Smedile and Costantino Vetriani
Microorganisms 2023, 11(6), 1366; https://doi.org/10.3390/microorganisms11061366 - 23 May 2023
Cited by 2 | Viewed by 1905
Abstract
Varunaivibrio sulfuroxidans type strain TC8T is a mesophilic, facultatively anaerobic, facultatively chemolithoautotrophic alphaproteobacterium isolated from a sulfidic shallow-water marine gas vent located at Tor Caldara, Tyrrhenian Sea, Italy. V. sulfuroxidans belongs to the family Thalassospiraceae within the Alphaproteobacteria, with Magnetovibrio blakemorei as its [...] Read more.
Varunaivibrio sulfuroxidans type strain TC8T is a mesophilic, facultatively anaerobic, facultatively chemolithoautotrophic alphaproteobacterium isolated from a sulfidic shallow-water marine gas vent located at Tor Caldara, Tyrrhenian Sea, Italy. V. sulfuroxidans belongs to the family Thalassospiraceae within the Alphaproteobacteria, with Magnetovibrio blakemorei as its closest relative. The genome of V. sulfuroxidans encodes the genes involved in sulfur, thiosulfate and sulfide oxidation, as well as nitrate and oxygen respiration. The genome encodes the genes involved in carbon fixation via the Calvin–Benson–Bassham cycle, in addition to genes involved in glycolysis and the TCA cycle, indicating a mixotrophic lifestyle. Genes involved in the detoxification of mercury and arsenate are also present. The genome also encodes a complete flagellar complex, one intact prophage and one CRISPR, as well as a putative DNA uptake mechanism mediated by the type IVc (aka Tad pilus) secretion system. Overall, the genome of Varunaivibrio sulfuroxidans highlights the organism’s metabolic versatility, a characteristic that makes this strain well-adapted to the dynamic environmental conditions of sulfidic gas vents. Full article
(This article belongs to the Special Issue Genomics of Extremophiles and Archaea)
Show Figures

Figure 1

12 pages, 2094 KiB  
Article
Biocorrosion of Carbon Steel under Controlled Laboratory Conditions
by Francisco Córdoba and Aguasanta M. Sarmiento
Minerals 2023, 13(5), 598; https://doi.org/10.3390/min13050598 - 26 Apr 2023
Cited by 1 | Viewed by 1811
Abstract
In the Iberian Pyritic Belt (SW Europe), Acid Mine Drainage (AMD) is the consequence of the interaction of physical-chemical and biological factors, where aerobic Fe and/or S oxidizing chemolithotrophic and anaerobic sulfate reducing bacteria play an essential role. As a result, the polluted [...] Read more.
In the Iberian Pyritic Belt (SW Europe), Acid Mine Drainage (AMD) is the consequence of the interaction of physical-chemical and biological factors, where aerobic Fe and/or S oxidizing chemolithotrophic and anaerobic sulfate reducing bacteria play an essential role. As a result, the polluted waters are highly acidic (pH 2–3) and contain numerous dissolved or suspended metals, which gives them a powerful corrosive action on constructions related to mining activities with high economic losses. To verify the role of bacteria in the corrosion of carbon steel, a common material in buildings exposed to corrosion in acidic waters, several experiments have been carried out under controlled conditions using carbon steel bars and acidic water containing bacteria consortia from an AMD river of the Iberian Pyritic Belt. In all the experiments carried out, a remarkable oxidation of supplemented iron was observed in the presence of bacteria. Using carbon steel as the sole iron source, we observed a slight corrosion of the bars, but when culture media was supplemented with elemental sulfur, steel bars was severely damaged. Since the bacteria inoculum come from the surface water, well oxygenated, nutrient-poor river, the obtained results are discussed based on facultative metabolism of acidophilic chemolithotrophic bacteria. Full article
Show Figures

Figure 1

13 pages, 2227 KiB  
Article
Two New Species of Filamentous Sulfur Bacteria of the Genus Thiothrix, Thiothrix winogradskyi sp. nov. and ‘Candidatus Thiothrix sulfatifontis’ sp. nov.
by Nikolai V. Ravin, Simona Rossetti, Alexey V. Beletsky, Vitaly V. Kadnikov, Tatyana S. Rudenko, Dmitry D. Smolyakov, Marina I. Moskvitina, Maria V. Gureeva, Andrey V. Mardanov and Margarita Yu. Grabovich
Microorganisms 2022, 10(7), 1300; https://doi.org/10.3390/microorganisms10071300 - 27 Jun 2022
Cited by 13 | Viewed by 3849 | Correction
Abstract
The metagenome of foulings from sulfidic spring “Serovodorodny” (Tatarstan, Russia), where members of the genus Thiothrix was observed, was sequenced. Representatives of the phyla Gammaproteobacteria, Cyanobacteria and Campilobacteriota dominated in the microbial community. The complete genome of Thiothrix sp. KT was assembled [...] Read more.
The metagenome of foulings from sulfidic spring “Serovodorodny” (Tatarstan, Russia), where members of the genus Thiothrix was observed, was sequenced. Representatives of the phyla Gammaproteobacteria, Cyanobacteria and Campilobacteriota dominated in the microbial community. The complete genome of Thiothrix sp. KT was assembled from the metagenome. It displayed 93.93–99.72% 16S rRNA gene sequence identity to other Thiothrix species. The average nucleotide identity (ANI) и digital DNA-DNA hybridization (dDDH) showed that the genome designated KT represents a new species within the genus Thiothrix, ‘Candidatus Thiothrix sulfatifontis’ sp. nov. KT. The taxonomic status has been determined of the strain Thiothrix sp. CT3, isolated about 30 years ago and not assigned to any of Thiothrix species due to high 16S rRNA gene sequence identity with related species (i.e., 98.8–99.4%). The complete genome sequence of strain CT3 was determined. The ANI between CT3 and other Thiothrix species was below 82%, and the dDDH values were less than 40%, indicating that strain CT3 belongs to a novel species, Thiothrix winogradskyi sp. nov. A genome analysis showed that both strains are chemo-organoheterotrophs, chemolithotrophs (in the presence of hydrogen sulfide and thiosulfate) and chemoautotrophs. For the first time, representatives of Thiothrix showed anaerobic growth in the presence of thiosulfate. Full article
(This article belongs to the Special Issue Genome Analysis of Microbial Communities in the Environment)
Show Figures

Figure 1

18 pages, 1157 KiB  
Article
Lab-Scale Cultivation of Cupriavidus necator on Explosive Gas Mixtures: Carbon Dioxide Fixation into Polyhydroxybutyrate
by Vera Lambauer and Regina Kratzer
Bioengineering 2022, 9(5), 204; https://doi.org/10.3390/bioengineering9050204 - 10 May 2022
Cited by 37 | Viewed by 7650
Abstract
Aerobic, hydrogen oxidizing bacteria are capable of efficient, non-phototrophic CO2 assimilation, using H2 as a reducing agent. The presence of explosive gas mixtures requires strict safety measures for bioreactor and process design. Here, we report a simplified, reproducible, and safe cultivation [...] Read more.
Aerobic, hydrogen oxidizing bacteria are capable of efficient, non-phototrophic CO2 assimilation, using H2 as a reducing agent. The presence of explosive gas mixtures requires strict safety measures for bioreactor and process design. Here, we report a simplified, reproducible, and safe cultivation method to produce Cupriavidus necator H16 on a gram scale. Conditions for long-term strain maintenance and mineral media composition were optimized. Cultivations on the gaseous substrates H2, O2, and CO2 were accomplished in an explosion-proof bioreactor situated in a strong, grounded fume hood. Cells grew under O2 control and H2 and CO2 excess. The starting gas mixture was H2:CO2:O2 in a ratio of 85:10:2 (partial pressure of O2 0.02 atm). Dissolved oxygen was measured online and was kept below 1.6 mg/L by a stepwise increase of the O2 supply. Use of gas compositions within the explosion limits of oxyhydrogen facilitated production of 13.1 ± 0.4 g/L total biomass (gram cell dry mass) with a content of 79 ± 2% poly-(R)-3-hydroxybutyrate in a simple cultivation set-up with dissolved oxygen as the single controlled parameter. Approximately 98% of the obtained PHB was formed from CO2. Full article
(This article belongs to the Special Issue Advances in Polyhydroxyalkanoate (PHA) Production, Volume 3)
Show Figures

Graphical abstract

11 pages, 5521 KiB  
Article
A Case of Predominance of Alicyclobacillus tolerans in Microbial Community during Bioleaching of Pentlandite-Chalcopyrite Concentrate
by Anna Panyushkina, Maxim Muravyov and Natalya Fomchenko
Minerals 2022, 12(4), 396; https://doi.org/10.3390/min12040396 - 23 Mar 2022
Cited by 7 | Viewed by 2385
Abstract
Bacterial isolates assigned to the species Alicyclobacillus tolerans, which occupies an intermediate position between an organotrophic genus Alicyclobacillus and mixotrophic genus Sulfobacillus, were revealed as members of the acidophilic chemolithotrophic community during stirred-tank bioleaching of violarite–pentlandite–chalcopyrite concentrate at 40 °C. Surprisingly, [...] Read more.
Bacterial isolates assigned to the species Alicyclobacillus tolerans, which occupies an intermediate position between an organotrophic genus Alicyclobacillus and mixotrophic genus Sulfobacillus, were revealed as members of the acidophilic chemolithotrophic community during stirred-tank bioleaching of violarite–pentlandite–chalcopyrite concentrate at 40 °C. Surprisingly, this species succeeded more common iron-oxidizing community members after a series of bioleaching processes in bioreactors. The possibility of mixotrophic and organoheterotrophic growth of Al. tolerans, tolerance to low pH values (1.0–1.15), as well as preservation of cells via sporulation under unfavorable conditions, may explain its key role in the bioleaching of the copper–nickel bulk concentrate. Isolation of two other sulfur-oxidizing pure cultures dominating the microbial community, together with their phylogenetic characterization, allowed the assignment of these isolates to the species Acidithiobacillus caldus. This and other studies of acidophilic microbial communities are important for the development and intensification of the bioleaching processes, including a biobeneficiation approach previously proposed by us. Full article
(This article belongs to the Special Issue Microorganisms and Minerals in Natural and Engineered Environments)
Show Figures

Figure 1

9 pages, 1620 KiB  
Article
Methanogenesis from Mineral Carbonates, a Potential Indicator for Life on Mars
by Richard M. Wormald, Jeremy Hopwood, Paul N. Humphreys, William Mayes, Helena I. Gomes and Simon P. Rout
Geosciences 2022, 12(3), 138; https://doi.org/10.3390/geosciences12030138 - 16 Mar 2022
Cited by 5 | Viewed by 4438
Abstract
Priorities for the exploration of Mars involve the identification and observation of biosignatures that indicate the existence of life on the planet. The atmosphere and composition of the sediments on Mars suggest suitability for anaerobic chemolithotrophic metabolism. Carbonates are often considered as morphological [...] Read more.
Priorities for the exploration of Mars involve the identification and observation of biosignatures that indicate the existence of life on the planet. The atmosphere and composition of the sediments on Mars suggest suitability for anaerobic chemolithotrophic metabolism. Carbonates are often considered as morphological biosignatures, such as stromatolites, but have not been considered as potential electron acceptors. Within the present study, hydrogenotrophic methanogen enrichments were generated from sediments that had received significant quantities of lime from industrial processes (lime kiln/steel production). These enrichments were then supplemented with calcium carbonate powder or marble chips as a sole source of carbon. These microcosms saw a release of inorganic carbon into the liquid phase, which was subsequently removed, resulting in the generation of methane, with 0.37 ± 0.09 mmoles of methane observed in the steel sediment enrichments supplemented with calcium carbonate powder. The steel sediment microcosms and lime sediments with carbonate powder enrichments were dominated by Methanobacterium sp., whilst the lime/marble enrichments were more diverse, containing varying proportions of Methanomassiliicoccus, Methanoculleus and Methanosarcina sp. In all microcosm experiments, acetic acid was detected in the liquid phase. Our results indicate that chemolithotrophic methanogenesis should be considered when determining biosignatures for life on Mars. Full article
(This article belongs to the Special Issue Current and Future Perspectives in Microbial Carbonate Precipitation)
Show Figures

Graphical abstract

16 pages, 4754 KiB  
Article
An Autochthonous Acidithiobacillus ferrooxidans Metapopulation Exploited for Two-Step Pyrite Biooxidation Improves Au/Ag Particle Release from Mining Waste
by Andrea E. Jiménez-Paredes, Elvia F. Alfaro-Saldaña, Araceli Hernández-Sánchez and J. Viridiana García-Meza
Mining 2021, 1(3), 335-350; https://doi.org/10.3390/mining1030021 - 29 Nov 2021
Cited by 9 | Viewed by 4491
Abstract
Pyrite bio-oxidation by chemolithotrophic acidophile bacteria has been applied in the mining industry to bioleach metals or to remove pyritic sulfur from coal. In this process, it is desirable to use autochthonous and already adapted bacteria isolated directly from the mining sites where [...] Read more.
Pyrite bio-oxidation by chemolithotrophic acidophile bacteria has been applied in the mining industry to bioleach metals or to remove pyritic sulfur from coal. In this process, it is desirable to use autochthonous and already adapted bacteria isolated directly from the mining sites where biomining will be applied. Bacteria present in the remnant solution from a mining company were identified through cloning techniques. For that purpose, we extracted total RNA and performed reverse transcription using a novel pair of primers designed from a small region of the 16S gene (V1–V3) that contains the greatest intraspecies diversity. After cloning, a high proportion of individuals of the strains ATCC-23270 (NR_074193.1 and NR_041888.1) and DQ321746.1 of the well-known species Acidithiobacillus ferrooxidans were found, as well as two new wild strains of A. ferrooxidans. This result showed that the acidic remnant solution comprises a metapopulation. We assayed these strains to produce bioferric flocculant to enhance the subsequent pyrite bio-oxidation, applying two-stage chemical–bacterial oxidation. It was shown that the strains were already adapted to a high concentration of endogenous Fe2+ (up to 20 g·L−1), increasing the volumetric productivity of the bioferric flocculant. Thus, no preadaptation of the community was required. We detected Au and Ag particles originally occluded in the old pyritic flotation tailings assayed, but the extraction of Au and Ag by cyanidation resulted in ca. 30.5% Au and 57.9% Ag. Full article
(This article belongs to the Topic Bio-Recovery of Precious Metals from Waste)
Show Figures

Figure 1

19 pages, 6803 KiB  
Article
Procaryotic Diversity and Hydrogenotrophic Methanogenesis in an Alkaline Spring (La Crouen, New Caledonia)
by Marianne Quéméneur, Nan Mei, Christophe Monnin, Anne Postec, Laura Wils, Manon Bartoli, Sophie Guasco, Bernard Pelletier and Gael Erauso
Microorganisms 2021, 9(7), 1360; https://doi.org/10.3390/microorganisms9071360 - 23 Jun 2021
Cited by 6 | Viewed by 3410
Abstract
(1) Background: The geothermal spring of La Crouen (New Caledonia) discharges warm (42 °C) alkaline water (pH~9) enriched in dissolved nitrogen with traces of methane, but its microbial diversity has not yet been studied. (2) Methods: Cultivation-dependent and -independent methods (e.g., Illumina sequencing [...] Read more.
(1) Background: The geothermal spring of La Crouen (New Caledonia) discharges warm (42 °C) alkaline water (pH~9) enriched in dissolved nitrogen with traces of methane, but its microbial diversity has not yet been studied. (2) Methods: Cultivation-dependent and -independent methods (e.g., Illumina sequencing and quantitative PCR based on 16S rRNA gene) were used to describe the prokaryotic diversity of this spring. (3) Results: Prokaryotes were mainly represented by Proteobacteria (57% on average), followed by Cyanobacteria, Chlorofexi, and Candidatus Gracilibacteria (GN02/BD1-5) (each > 5%). Both potential aerobes and anaerobes, as well as mesophilic and thermophilic microorganisms, were identified. Some of them had previously been detected in continental hyperalkaline springs found in serpentinizing environments (The Cedars, Samail, Voltri, and Zambales ophiolites). Gammaproteobacteria, Ca. Gracilibacteria and Thermotogae were significantly more abundant in spring water than in sediments. Potential chemolithotrophs mainly included beta- and gammaproteobacterial genera of sulfate-reducers (Ca. Desulfobacillus), methylotrophs (Methyloversatilis), sulfur-oxidizers (Thiofaba, Thiovirga), or hydrogen-oxidizers (Hydrogenophaga). Methanogens (Methanobacteriales and Methanosarcinales) were the dominant Archaea, as found in serpentinization-driven and deep subsurface ecosystems. A novel alkaliphilic hydrogenotrophic methanogen (strain CAN) belonging to the genus Methanobacterium was isolated, suggesting that hydrogenotrophic methanogenesis occurs at La Crouen. Full article
(This article belongs to the Special Issue Diversity of Extremophiles in Hydrothermal Environments)
Show Figures

Figure 1

19 pages, 2641 KiB  
Article
Cultivation and Molecular Studies to Reveal the Microbial Communities of Groundwaters Discharge Located in Hungary
by Marwene Toumi, Gorkhmaz Abbaszade, Yousra Sbaoui, Rózsa Farkas, Éva Ács, Laura Jurecska and Erika Tóth
Water 2021, 13(11), 1533; https://doi.org/10.3390/w13111533 - 29 May 2021
Cited by 5 | Viewed by 5029
Abstract
In the present study 12 water samples of five sampling sites (Tatabánya, Dandár, Szentendre, Szent Flórián and Ciprián groundwaters) known as nutrient-depleted aquatic environments were studied using amplicon sequencing (NGS) and cultivation techniques. Diversity indices and cell counts were determined to assess the [...] Read more.
In the present study 12 water samples of five sampling sites (Tatabánya, Dandár, Szentendre, Szent Flórián and Ciprián groundwaters) known as nutrient-depleted aquatic environments were studied using amplicon sequencing (NGS) and cultivation techniques. Diversity indices and cell counts were determined to assess the species richness in relation to the cell counts within the samples, and the oligocarbophile growth capability of the isolated bacteria was tested in microtiter plates. Altogether, 55 bacterial phyla were identified from the samples by amplicon sequencing. The microbial communities of the different sampling times of the same sites did not differ significantly. Patescibacteria and Proteobacteria were present in all samples. Ciprián sample was dominated by Bacteroidetes, while in Dandár sample a high ratio of Chloroflexi was detected. Rokubacteria and WOR-1 dominated Szent Flórián sample and Tatabánya had a high number of Epsilonbacteraeota. Nine archaeal phyla were also detected; the samples were characterized by the presence of unclassified archaea and Nanoarchaeota, among them Woesearchaeia, as the most dominant. Crenarchaeota and Altiarchaeota were detected in high ratios in Dandár water samples. Among Thaumarchaeota the family Nitrosopumilaceae, and orders of Nitrosotaleales and Nitrososphaerales appeared in Szent Flórián and Tatabánya samples. Key organisms of the different biogeochemical cycles were discovered in these nutrient-depleted environments: methanogenic archaea, methanotrophic bacteria, ammonia oxidizer, nitrate reducers, diazotrophs, sulfate reducers, and sulfur oxidizer. Diversity indices and cell counts of the samples show negative correlation in case of bacteria and positive in case of archaea in Ciprián sample. The high diversity indices in Szentendre samples are connected to low cell counts, most probably due to the vulnerability of the groundwaters to the external environment factors which lead to the infiltration of soil microbes and contaminants to the water. The isolated bacteria were affiliated into four phyla, most of them belonging to Proteobacteria (59%) followed by Actinobacteria (21%), Firmicutes (17%) and Verrucomicrobia (1%). The members of the facultative chemolithotrophic genera of Sphingobium, Sphingomonas, Sphingopyxis were characterizing only Szentendre, Szent Flórián and Tatabánya samples. Only 10% of the isolated species showed an obligate oligocarbophile character. From the samples, a high number of novel bacterial taxa were cultivated. As a conclusion, our results confirmed the predominance of unclassified and unknown taxa in subsurface water, pointing to the importance and necessity of further studies to characterize these microbial populations. Full article
(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)
Show Figures

Figure 1

Back to TopTop