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Mauro Tonolla - One of the best experts on this subject based on the ideXlab platform.
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Iron isotope transformations in the Meromictic Lake Cadagno
Geochimica et Cosmochimica Acta, 2019Co-Authors: Michael J. Ellwood, Mauro Tonolla, Sandro Peduzzi, Francesco Danza, Christel S. Hassler, Sophie A. M. Moisset, Ludovic Pascal, Derek VanceAbstract:Abstract The iron isotope composition of sedimentary deposits is a key tool for tracking changes in the biogeochemical and redox conditions of modern and geologically ancient aquatic systems. The use of iron isotopes to reconstruct oxic, anoxic and redox conditions is based on iron isotope fractionation associated with the iron(II)–iron(III) redox reaction and the formation of various iron oxy, hydroxy and sulfur species. However, the degree of iron isotope fractionation varies within the sedimentary record, and the processes leading to isotope fractionation within aquatic systems also vary. Here we investigate iron isotope fractionation within the water column of Lake Cadagno, Switzerland. Lake Cadagno is a 21 m deep alpine Meromictic Lake that is permanently stratified. It has two chemically distinct water layers: an oxic mixolimnion separated by a narrow chemocline from an anoxic monimolimnion. The chemocline is located across a narrow band between 10 and 13.5 m and is defined by steep chemical gradients in dissolved oxygen, redox potential, nutrients (nitrite + nitrate, ammonia), dissolved and particulate trace metals (iron and manganese) and sulfur species. Iron isotope determination (56Fe/54Fe ratio; expressed as δ56Fe) of both dissolved (δ56Fedissolved) and particulate (δ56Feparticulate) iron reveals a sharp transition within the chemocline with a heavy δ56Fedissolved value (+0.75‰) at 11.5 m and light δ56Fedissolved value (−0.61‰) below at 12 m. The large shift in δ56Fedissolved occurs where anoxygenic phototrophic bacteria become abundant. Modelling of the dissolved iron isotope fractionation within the chemocline produced fractionation factors of −0.60‰ (kinetic model) and −1.52‰ (equilibrium model) assuming a two-step process involving iron oxidation followed by precipitation. Changes in the isotope composition of particulate iron with depth are subtler to that of dissolved iron, with slightly lighter values (−0.18‰) above the chemocline and slightly heavier values (+0.13‰) below. The production of reduced iron(II) within and below the chemocline is likely coupled to dissimilatory iron(III) reduction and dissolution reactions associated with sinking iron(III) oxy and hydroxy species. These processes lead to a peak in dissolved iron concentrations at 12.5 m. The decline in dissolved iron concentration below this depth and its change in isotope composition is consistent with the formation of iron sulphide species, e.g. mackinawite, under mildly euxinic conditions. Overall our results indicate that variations in δ56Fedissolved likely involve a combination of biotic and abiotic processes with biological mixing enhancing the rate at which iron(II) is transferred across the chemocline. The observed isotope transformation of dissolved iron across the chemocline of Lake Cadagno may make it a reasonable analogue to past shallow-water systems with mild euxinia.
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Bacterial diversity in the water column of Meromictic Lake Cadagno and evidence for seasonal dynamics.
PloS one, 2018Co-Authors: Francesco Danza, Nicola Storelli, Samuele Roman, Samuele Lüdin, Damiana Ravasi, Matthieu Bueche, Mauro TonollaAbstract:The Meromictic Lake Cadagno is characterized by a compact chemocline with high concentrations of anoxygenic phototrophic purple and green sulfur bacteria. However, a complete picture of the bacterial diversity, and in particular of effects of seasonality and compartmentalization is missing. To characterize bacterial communities and elucidate relationships between them and their surrounding environment high-throughput 16S rRNA gene pyrosequencing was conducted. Proteobacteria, Chlorobi, Verrucomicrobia, and Actinobacteria were the dominant groups in Lake Cadagno water column. Moreover, bacterial interaction within the chemocline and between oxic and anoxic Lake compartments were investigated through fluorescence in situ hybridization (FISH) and flow cytometry (FCM). The different populations of purple sulfur bacteria (PSB) and green sulfur bacteria (GSB) in the chemocline indicate seasonal dynamics of phototrophic sulfur bacteria composition. Interestingly, an exceptional bloom of a cyanobacteria population in the oxic-anoxic transition zone affected the common spatial distribution of phototrophic sulfur bacteria with consequence on chemocline location and water column stability. Our study suggests that both bacterial interactions between different Lake compartments and within the chemocline can be a dynamic process influencing the stratification structure of Lake Cadagno water column.
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Complete genome sequence of “Thiodictyon syntrophicum” sp. nov. strain Cad16^T, a photolithoautotrophic purple sulfur bacterium isolated from the alpine Meromictic Lake Cadagno
Standards in Genomic Sciences, 2018Co-Authors: Samuel M Luedin, Francesco Danza, Nicola Storelli, Joel F Pothier, Nielsulrik Frigaard, Matthias Wittwer, Mauro TonollaAbstract:“ Thiodictyon syntrophicum” sp. nov. strain Cad16^T is a photoautotrophic purple sulfur bacterium belonging to the family of Chromatiaceae in the class of Gammaproteobacteria . The type strain Cad16^T was isolated from the chemocline of the alpine Meromictic Lake Cadagno in Switzerland. Strain Cad16^T represents a key species within this sulfur-driven bacterial ecosystem with respect to carbon fixation. The 7.74-Mbp genome of strain Cad16^T has been sequenced and annotated. It encodes 6237 predicted protein sequences and 59 RNA sequences. Phylogenetic comparison based on 16S rRNA revealed that Thiodictyon elegans strain DSM 232^T the most closely related species. Genes involved in sulfur oxidation, central carbon metabolism and transmembrane transport were found. Noteworthy, clusters of genes encoding the photosynthetic machinery and pigment biosynthesis are found on the 0.48 Mb plasmid pTs485. We provide a detailed insight into the Cad16^T genome and analyze it in the context of the microbial ecosystem of Lake Cadagno.
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Dynamic cellular complexity of anoxygenic phototrophic sulfur bacteria in the chemocline of Meromictic Lake Cadagno.
PloS one, 2017Co-Authors: Francesco Danza, Nicola Storelli, Samuele Roman, Samuele Lüdin, Mauro TonollaAbstract:The Meromictic Lake Cadagno is characterized by a compact chemocline with high concentrations of anoxygenic phototrophic purple sulfur bacteria (PSB) and green sulfur bacteria (GSB). The co-occurrence of phylogenetically distant bacterial groups such as PSB and GSB in the same ecological niche, makes the chemocline of Lake Cadagno an ideal system for studying the conditions and consequences of coexistence of photosynthetic bacteria populations. In this study, we applied flow cytometry (FCM) as a fast tool to identify metabolic changes due to the production and consumption of inclusion bodies such as sulfur globules (SGBs), and follow population dynamics of closely related anoxygenic photosynthetic sulfur bacteria in their natural environment. Large-celled PSB Chromatium okenii and GSB Chlorobium populations were reliably separated and identified due to differences in auto-fluorescence and cell size. Moreover, we showed that these dominant taxa share the same ecological niche over seasonal periods. Taking advantage of FCM detection of dynamic cellular complexity variation during phases of photosynthetic activity, we identified an unexpected alternation in PSB versus GSB metabolic activity, indicating dynamic interspecific interactions between these two populations.
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combining sedimentological trace metal mn mo and molecular evidence for reconstructing past water column redox conditions the example of Meromictic Lake cadagno swiss alps
Geochimica et Cosmochimica Acta, 2013Co-Authors: Stefanie B Wirth, Raffaele Peduzzi, Sandro Peduzzi, Damiana Ravasi, Adrian Gilli, Helge Niemann, Tais W Dahl, Nadja Sax, Yvonne Hamann, Mauro TonollaAbstract:Here, we present sedimentological, trace metal, and molecular evidence for tracking bottom water redox-state conditions during the past 12,500 years in nowadays sulfidic and Meromictic Lake Cadagno (Switzerland). A 10.5 m long sediment core from the Lake covering the Holocene period was investigated for concentration variations of the trace metals Mn and Mo (XRF core scanning and ICP-MS measurements), and for the presence of anoxygenic phototrophic sulfur bacteria (carotenoid pigment analysis and 16S rDNA real time PCR). Our trace metal analysis documents an oxic-intermediate-sulfidic redox-transition period beginning shortly after the Lake formation similar to 12.5 kyr ago. The oxic period is characterized by low sedimentary Mn and Mo concentrations, as well as by the absence of any remnants of anoxygenic phototrophic sulfur bacteria. Enhanced accumulation/preservation of Mn (up to 5.6 wt%) in the sediments indicates an intermediate, Mn-enriched oxygenation state with fluctuating redox conditions during a similar to 2300-year long transition interval between similar to 12.1 and 9.8 kyr BP. We propose that the high Mn concentrations are the result of enhanced Mn2+ leaching from the sediments during reducing conditions and subsequent rapid precipitation of Mn-(oxyhydr) oxide minerals during episodic and short-term water-column mixing events mainly due to flood-induced underflows. At 9800 +/- 130 cal yr BP, a rapid transition to fully sulfidic conditions is indicated by the marked enrichment of Mo in the sediments (up to 490 ppm), accompanied by an abrupt drop in Mn concentrations and the increase of molecular biomarkers that indicate the presence of anoxygenic photosynthetic bacteria in the water column. Persistently high Mo concentrations >80 ppm provide evidence that sulfidic conditions prevailed thereafter until modern times, without any lasting hypolimnetic ventilation and reoxygenation. Hence, Lake Cadagno with its persistently stable chemocline offers a framework to study in great temporal detail over similar to 12 kyr the development of phototrophic sulfur bacteria communities and redox processes in a sulfidic environment, possibly depicting analogous conditions in an ancient ocean. Our study underscores the value of combining sedimentological, geochemical, and microbiological approaches to characterize paleo-environmental and -redox conditions in lacustrine and marine settings.
Manabu Fukui - One of the best experts on this subject based on the ideXlab platform.
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Desulfoplanes formicivorans gen. nov., sp nov., a novel sulfate-reducing bacterium isolated from a blackish Meromictic Lake, and emended description of the family Desulfomicrobiaceae
International Journal of Systematic and Evolutionary Microbiology, 2015Co-Authors: Miho Watanabe, Hisaya Kojima, Manabu FukuiAbstract:A novel sulfate-reducing bacterium, designated strain Pf12BT, was isolated from sediment of Meromictic Lake Harutori in Japan. Cells were vibroid (1.0 × 3.0–4.0 μm), motile and Gram-stain-negative. For growth, the optimum pH was 7.0–7.5 and the optimum temperature was 42–45 °C. Strain Pf12BT used sulfate, thiosulfate and sulfite as electron acceptors. The G+C content of the genomic DNA was 55.4 mol%. Major cellular fatty acids were C16 : 0 and C18 : 0. The strain was desulfoviridin-positive. Phylogenetic analysis based on the 16S rRNA gene revealed that the novel strain belonged to the order Desulfovibrionales in the class Deltaproteobacteria. The closest relative was Desulfomicrobium baculatum DSM 4028T with which it shared 91 % 16S rRNA gene sequence similarity. On the basis of phylogenetic and phenotypic characterization, a novel species of a new genus belonging to the family Desulfomicrobiaceae is proposed, Desulfoplanes formicivorans gen. nov., sp. nov. The type strain of Desulfoplanes formicivorans is Pf12BT ( = NBRC 110391T = DSM 28890T).
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Vertical distribution of major sulfate-reducing bacteria in a shallow eutrophic Meromictic Lake
Systematic and Applied Microbiology, 2014Co-Authors: Kyoko Kubo, Hisaya Kojima, Manabu FukuiAbstract:Abstract The vertical distribution of sulfate-reducing bacteria was investigated in a shallow, eutrophic, Meromictic Lake, Lake Harutori, located in a residential area of Kushiro, Japan. A steep chemocline, characterized by gradients of oxygen, sulfide and salinity, was found at a depth of 3.5–4.0 m. The sulfide concentration at the bottom of the Lake was high (up to a concentration of 10.7 mM). Clone libraries were constructed using the aprA gene, which encodes adenosine-5′-phosphosulfate reductase subunit A, in order to monitor sulfate-reducing bacteria. In the aprA clone libraries, the most abundant sequences were those from the Desulfosarcina–Desulfococcus (DSS) group. A primer set for a DSS group-specific 16S rRNA gene was used to construct another clone library, analysis of which revealed that the uncultured group of sulfate-reducing bacteria, SEEP SRB-1, accounted for nearly half of the obtained sequences. Quantification of the major bacterial groups by catalyzed reporter deposition-fluorescence in situ hybridization demonstrated that the DSS group accounted for 3.2–4.8% of the total bacterial community below the chemocline. The results suggested that the DSS group was one of the major groups of sulfate-reducing bacteria and that these presumably metabolically versatile bacteria might play an important role in sulfur cycling in Lake Harutori.
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potential sulfur metabolisms and associated bacteria within anoxic surface sediment from saline Meromictic Lake kaiike japan
FEMS Microbiology Ecology, 2005Co-Authors: Yoshikazu Koizumi, Hisaya Kojima, Manabu FukuiAbstract:The effects of light and of added electron donors and sulfur compounds on sulfur metabolisms in the microbial mat dilutions from the saline Meromictic Lake Kaiike were investigated. Sulfide concentrations in the mat dilution without any electron donor gradually increased by 0.6–1 mM in the dark. Additions of lactate, acetate, H2/CO2, propionate and iso-butylate stimulated sulfide production, whereas benzoate did not, indicating the limitation of sulfate reduction by available electron donor concentrations. More sulfide was produced, without a decrease of sulfate, in an elemental sulfur-amended dilution than in a non-amended control. In contrast, the addition of a high concentration of sulfide slowed down sulfide production. After enrichment under various conditions, microbial communities in the dilutions were characterized by a denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene and sequencing. As a result, microorganisms affiliated with mesophilic sulfate-reducing bacteria group within the Deltaproteobacteria and the Epsilonproteobacteria were mainly enriched by the addition of electrons used in this study, suggesting that these microorganisms might play an important role in sulfur metabolisms within the surficial sediment of Lake Kaiike.
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dominant microbial composition and its vertical distribution in saline Meromictic Lake kaiike japan as revealed by quantitative oligonucleotide probe membrane hybridization
Applied and Environmental Microbiology, 2004Co-Authors: Yoshikazu Koizumi, Hisaya Kojima, Manabu FukuiAbstract:Vertical distributions of dominant bacterial populations in saline Meromictic Lake Kaiike were investigated throughout the water column and sediment by quantitative oligonucleotide probe membrane hybridization. Three oligonucleotide probes specific for the small-subunit (SSU) rRNA of three groups of Chlorobiaceae were newly designed. In addition, three general domain (Bacteria, Archaea, and Eukarya)-specific probes, two δ-Proteobacteria-specific probes, a Chlorobiaceae-specific probe, and a Chloroflexi-specific probe were used after optimization of their washing conditions. The abundance of the sum of SSU rRNAs hybridizing with probes specific for three groups of Chlorobiaceae relative to total SSU rRNA peaked in the chemocline, accounting for up to 68%. The abundance of the δ-proteobacterial SSU rRNA relative to total SSU rRNA rapidly increased just below the chemocline up to 29% in anoxic water and peaked at the 2- to 3-cm sediment depth at ca. 34%. The abundance of SSU rRNAs hybridizing with the probe specific for the phylum Chloroflexi relative to total SSU rRNA was highest (31 to 54%) in the top of the sediment but then steeply declined with depth and became stable at 11 to 19%, indicating the robust coexistence of sulfate-reducing bacteria and Chloroflexi in the top of the sediment. Any SSU rRNA of Chloroflexi in the water column was under the detection limit. The summation of the signals of group-specific probes used in this study accounted for up to 89% of total SSU rRNA, suggesting that the DGGE-oligonucleotide probe hybridization approach, in contrast to conventional culture-dependent approaches, was very effective in covering dominant populations.
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vertical and temporal shifts in microbial communities in the water column and sediment of saline Meromictic Lake kaiike japan as determined by a 16s rdna based analysis and related to physicochemical gradients
Environmental Microbiology, 2004Co-Authors: Yoshikazu Koizumi, Kazumasa Oguri, Hiroshi Kitazato, Hisaya Kojima, Manabu FukuiAbstract:Summary The vertical and temporal changes in microbial communities were investigated throughout the water column and sediment of the saline Meromictic Lake Kaiike by PCR-denaturing gradient gel electrophoresis (DGGE) of 16S rDNA. Marked depth-related changes in microbial communities were observed at the chemocline and the sediment–water interface. However, no major temporal changes in the microbial community below the chemocline were observed during the sampling period, suggesting that the ecosystem in the anoxic zone of Lake Kaiike was nearly stable. Although the sequence of the most conspicuous DGGE band throughout the anoxic water and in the top of the microbial mat was most similar to that of an anoxic, photosynthetic, green sulphur bacterium, Pelodyction luteolum DSM273 (97% similarity), it represented a new phylotype. A comparison of DGGE banding patterns of the water column and sediment samples demonstrated that specific bacteria accumulated on the bottom from the anoxic water layers, and that indigenous microbial populations were present in the sediment. The measurements of bicarbonate assimilation rates showed significant phototrophic assimilation in the chemocline and lithoautotrophic assimilation throughout the anoxic water, but were not clearly linked with net sulphide turnover rates, indicating that sulphur and carbon metabolisms were not directly correlated.
Samuel M Luedin - One of the best experts on this subject based on the ideXlab platform.
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complete genome sequence of thiodictyon syntrophicum sp nov strain cad16t a photolithoautotrophic purple sulfur bacterium isolated from the alpine Meromictic Lake cadagno
Standards in Genomic Sciences, 2018Co-Authors: Francesco Danza, Nicola Storelli, Samuel M Luedin, Joel F Pothier, Nielsulrik Frigaard, Matthias WittwerAbstract:“Thiodictyon syntrophicum” sp. nov. strain Cad16T is a photoautotrophic purple sulfur bacterium belonging to the family of Chromatiaceae in the class of Gammaproteobacteria. The type strain Cad16T was isolated from the chemocline of the alpine Meromictic Lake Cadagno in Switzerland. Strain Cad16T represents a key species within this sulfur-driven bacterial ecosystem with respect to carbon fixation. The 7.74-Mbp genome of strain Cad16T has been sequenced and annotated. It encodes 6237 predicted protein sequences and 59 RNA sequences. Phylogenetic comparison based on 16S rRNA revealed that Thiodictyon elegans strain DSM 232T the most closely related species. Genes involved in sulfur oxidation, central carbon metabolism and transmembrane transport were found. Noteworthy, clusters of genes encoding the photosynthetic machinery and pigment biosynthesis are found on the 0.48 Mb plasmid pTs485. We provide a detailed insight into the Cad16T genome and analyze it in the context of the microbial ecosystem of Lake Cadagno.
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Complete genome sequence of “Thiodictyon syntrophicum” sp. nov. strain Cad16^T, a photolithoautotrophic purple sulfur bacterium isolated from the alpine Meromictic Lake Cadagno
Standards in Genomic Sciences, 2018Co-Authors: Samuel M Luedin, Francesco Danza, Nicola Storelli, Joel F Pothier, Nielsulrik Frigaard, Matthias Wittwer, Mauro TonollaAbstract:“ Thiodictyon syntrophicum” sp. nov. strain Cad16^T is a photoautotrophic purple sulfur bacterium belonging to the family of Chromatiaceae in the class of Gammaproteobacteria . The type strain Cad16^T was isolated from the chemocline of the alpine Meromictic Lake Cadagno in Switzerland. Strain Cad16^T represents a key species within this sulfur-driven bacterial ecosystem with respect to carbon fixation. The 7.74-Mbp genome of strain Cad16^T has been sequenced and annotated. It encodes 6237 predicted protein sequences and 59 RNA sequences. Phylogenetic comparison based on 16S rRNA revealed that Thiodictyon elegans strain DSM 232^T the most closely related species. Genes involved in sulfur oxidation, central carbon metabolism and transmembrane transport were found. Noteworthy, clusters of genes encoding the photosynthetic machinery and pigment biosynthesis are found on the 0.48 Mb plasmid pTs485. We provide a detailed insight into the Cad16^T genome and analyze it in the context of the microbial ecosystem of Lake Cadagno.
Francesco Danza - One of the best experts on this subject based on the ideXlab platform.
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Iron isotope transformations in the Meromictic Lake Cadagno
Geochimica et Cosmochimica Acta, 2019Co-Authors: Michael J. Ellwood, Mauro Tonolla, Sandro Peduzzi, Francesco Danza, Christel S. Hassler, Sophie A. M. Moisset, Ludovic Pascal, Derek VanceAbstract:Abstract The iron isotope composition of sedimentary deposits is a key tool for tracking changes in the biogeochemical and redox conditions of modern and geologically ancient aquatic systems. The use of iron isotopes to reconstruct oxic, anoxic and redox conditions is based on iron isotope fractionation associated with the iron(II)–iron(III) redox reaction and the formation of various iron oxy, hydroxy and sulfur species. However, the degree of iron isotope fractionation varies within the sedimentary record, and the processes leading to isotope fractionation within aquatic systems also vary. Here we investigate iron isotope fractionation within the water column of Lake Cadagno, Switzerland. Lake Cadagno is a 21 m deep alpine Meromictic Lake that is permanently stratified. It has two chemically distinct water layers: an oxic mixolimnion separated by a narrow chemocline from an anoxic monimolimnion. The chemocline is located across a narrow band between 10 and 13.5 m and is defined by steep chemical gradients in dissolved oxygen, redox potential, nutrients (nitrite + nitrate, ammonia), dissolved and particulate trace metals (iron and manganese) and sulfur species. Iron isotope determination (56Fe/54Fe ratio; expressed as δ56Fe) of both dissolved (δ56Fedissolved) and particulate (δ56Feparticulate) iron reveals a sharp transition within the chemocline with a heavy δ56Fedissolved value (+0.75‰) at 11.5 m and light δ56Fedissolved value (−0.61‰) below at 12 m. The large shift in δ56Fedissolved occurs where anoxygenic phototrophic bacteria become abundant. Modelling of the dissolved iron isotope fractionation within the chemocline produced fractionation factors of −0.60‰ (kinetic model) and −1.52‰ (equilibrium model) assuming a two-step process involving iron oxidation followed by precipitation. Changes in the isotope composition of particulate iron with depth are subtler to that of dissolved iron, with slightly lighter values (−0.18‰) above the chemocline and slightly heavier values (+0.13‰) below. The production of reduced iron(II) within and below the chemocline is likely coupled to dissimilatory iron(III) reduction and dissolution reactions associated with sinking iron(III) oxy and hydroxy species. These processes lead to a peak in dissolved iron concentrations at 12.5 m. The decline in dissolved iron concentration below this depth and its change in isotope composition is consistent with the formation of iron sulphide species, e.g. mackinawite, under mildly euxinic conditions. Overall our results indicate that variations in δ56Fedissolved likely involve a combination of biotic and abiotic processes with biological mixing enhancing the rate at which iron(II) is transferred across the chemocline. The observed isotope transformation of dissolved iron across the chemocline of Lake Cadagno may make it a reasonable analogue to past shallow-water systems with mild euxinia.
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Bacterial diversity in the water column of Meromictic Lake Cadagno and evidence for seasonal dynamics.
PloS one, 2018Co-Authors: Francesco Danza, Nicola Storelli, Samuele Roman, Samuele Lüdin, Damiana Ravasi, Matthieu Bueche, Mauro TonollaAbstract:The Meromictic Lake Cadagno is characterized by a compact chemocline with high concentrations of anoxygenic phototrophic purple and green sulfur bacteria. However, a complete picture of the bacterial diversity, and in particular of effects of seasonality and compartmentalization is missing. To characterize bacterial communities and elucidate relationships between them and their surrounding environment high-throughput 16S rRNA gene pyrosequencing was conducted. Proteobacteria, Chlorobi, Verrucomicrobia, and Actinobacteria were the dominant groups in Lake Cadagno water column. Moreover, bacterial interaction within the chemocline and between oxic and anoxic Lake compartments were investigated through fluorescence in situ hybridization (FISH) and flow cytometry (FCM). The different populations of purple sulfur bacteria (PSB) and green sulfur bacteria (GSB) in the chemocline indicate seasonal dynamics of phototrophic sulfur bacteria composition. Interestingly, an exceptional bloom of a cyanobacteria population in the oxic-anoxic transition zone affected the common spatial distribution of phototrophic sulfur bacteria with consequence on chemocline location and water column stability. Our study suggests that both bacterial interactions between different Lake compartments and within the chemocline can be a dynamic process influencing the stratification structure of Lake Cadagno water column.
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complete genome sequence of thiodictyon syntrophicum sp nov strain cad16t a photolithoautotrophic purple sulfur bacterium isolated from the alpine Meromictic Lake cadagno
Standards in Genomic Sciences, 2018Co-Authors: Francesco Danza, Nicola Storelli, Samuel M Luedin, Joel F Pothier, Nielsulrik Frigaard, Matthias WittwerAbstract:“Thiodictyon syntrophicum” sp. nov. strain Cad16T is a photoautotrophic purple sulfur bacterium belonging to the family of Chromatiaceae in the class of Gammaproteobacteria. The type strain Cad16T was isolated from the chemocline of the alpine Meromictic Lake Cadagno in Switzerland. Strain Cad16T represents a key species within this sulfur-driven bacterial ecosystem with respect to carbon fixation. The 7.74-Mbp genome of strain Cad16T has been sequenced and annotated. It encodes 6237 predicted protein sequences and 59 RNA sequences. Phylogenetic comparison based on 16S rRNA revealed that Thiodictyon elegans strain DSM 232T the most closely related species. Genes involved in sulfur oxidation, central carbon metabolism and transmembrane transport were found. Noteworthy, clusters of genes encoding the photosynthetic machinery and pigment biosynthesis are found on the 0.48 Mb plasmid pTs485. We provide a detailed insight into the Cad16T genome and analyze it in the context of the microbial ecosystem of Lake Cadagno.
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Complete genome sequence of “Thiodictyon syntrophicum” sp. nov. strain Cad16^T, a photolithoautotrophic purple sulfur bacterium isolated from the alpine Meromictic Lake Cadagno
Standards in Genomic Sciences, 2018Co-Authors: Samuel M Luedin, Francesco Danza, Nicola Storelli, Joel F Pothier, Nielsulrik Frigaard, Matthias Wittwer, Mauro TonollaAbstract:“ Thiodictyon syntrophicum” sp. nov. strain Cad16^T is a photoautotrophic purple sulfur bacterium belonging to the family of Chromatiaceae in the class of Gammaproteobacteria . The type strain Cad16^T was isolated from the chemocline of the alpine Meromictic Lake Cadagno in Switzerland. Strain Cad16^T represents a key species within this sulfur-driven bacterial ecosystem with respect to carbon fixation. The 7.74-Mbp genome of strain Cad16^T has been sequenced and annotated. It encodes 6237 predicted protein sequences and 59 RNA sequences. Phylogenetic comparison based on 16S rRNA revealed that Thiodictyon elegans strain DSM 232^T the most closely related species. Genes involved in sulfur oxidation, central carbon metabolism and transmembrane transport were found. Noteworthy, clusters of genes encoding the photosynthetic machinery and pigment biosynthesis are found on the 0.48 Mb plasmid pTs485. We provide a detailed insight into the Cad16^T genome and analyze it in the context of the microbial ecosystem of Lake Cadagno.
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Flow cytometry as a tool to investigate the anoxygenic phototrophic sulfur bacteria coexistence in the chemocline of Meromictic Lake Cadagno
2018Co-Authors: Francesco DanzaAbstract:The Meromictic Lake Cadagno is characterized by a compact chemocline with high concentration of anoxygenic phototrophic purple sulfur bacteria (PSB) and green sulfur bacteria (GSB). The co-occurrence of PSB and GSB in the same ecological niche makes the chemocline of Lake Cadagno an ideal system for studying the conditions and consequences of coexistence of photosynthetic bacteria population. In this study, flow cytometry (FCM) was applied as a fast tool to identify metabolic changes due to the production and consumption of inclusion bodies and to follow population dynamics of closely related anoxygenic photosynthetic sulfur bacteria in their natural environment. Through this technique the large-celled PSB Chromatium okenii and GSB Chlorobium populations were reliably separated and identified due to difference in auto-fluorescence and cell size. Moreover, we showed that these dominant taxa share the same ecological niche. Two mechanisms for this coexistence were proposed: population activity alternation and bioconvection.
Dittmar Hahn - One of the best experts on this subject based on the ideXlab platform.
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phototropic sulfur and sulfate reducing bacteria in the chemocline of Meromictic Lake cadagno switzerland
Journal of Limnology, 2004Co-Authors: Mauro Tonolla, Antonella Demarta, Raffaele Peduzzi, Sandro Peduzzi, Dittmar HahnAbstract:Lake Cadagno, a crenogenic Meromictic Lake located in the catchment area of a dolomite vein rich in gypsum in the Piora Valley in the southern Alps of Switzerland, is characterized by a compact chemocline with high concentrations of sulfate, steep gradients of oxygen, sulfide and light and a turbidity maximum that correlates to large numbers of bacteria (up to 107 cells ml-1). The most abundant taxa in the chemocline are large- and small-celled purple sulfur bacteria, which account for up to 35% of all bacteria, and sulfate- reducing bacteria that represent up to 23% of all bacteria. Depending on the season, as much as 45% of all bacteria in the chemocline are associated in aggregates consisting of different populations of small-celled purple sulfur bacteria of the genus Lamprocystis (up to 35% of all bacteria) and sulfate-reducing bacteria of the family Desulfobulbaceae (up to 12% of all bacteria) that are almost completely represented by bacteria closely related to Desulfocapsa thiozymogenes. Their association in aggregates is restricted to small-celled purple sulfur bacteria of the genus Lamprocystis, but not obligate since non-associated cells of bacteria related to D. thiozymogenes are frequently found, especially under limited light conditions in winter and early summer. Aggregate formation and concomitant growth enhancement of isolates of both partners of this association suggests synergistic interactions that might resemble a sulfide-based source-sink relationship between the sulfate-reducing bacterium that is able to sustain growth by a disproportionation of inorganic sulfur compounds (sulfur, thiosulfate, sulfite), with the purple sulfur bacteria acting as a biotic scavenger. The availability of these isolates opens up the door for future studies considering other facets of potential interactions in aggregates since both types of organisms are metabolically highly versatile and interactions may not be limited to sulfur compounds only.
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isolation and characterization of aggregate forming sulfate reducing and purple sulfur bacteria from the chemocline of Meromictic Lake cadagno switzerland
FEMS Microbiology Ecology, 2003Co-Authors: Sandro Peduzzi, Mauro Tonolla, Dittmar HahnAbstract:Abstract In situ hybridization with specific oligonucleotide probes was used to monitor enrichment cultures of yet uncultured populations of sulfate-reducing and small-celled purple sulfur bacteria found to associate into aggregates in the chemocline of Meromictic Lake Cadagno, Switzerland, and to select potential isolates. Enrichment and isolation conditions resembled those of their nearest cultured relatives, the sulfate-reducing bacterium Desulfocapsa thiozymogenes and small-celled purple sulfur bacteria belonging to the genus Lamprocystis, respectively. Based on comparative 16S rRNA analysis and physiological characterization, isolate Cad626 was found to resemble D. thiozymogenes although it differed from the type strain by its ability to grow on lactate and pyruvate. Like D. thiozymogenes, isolate Cad626 was able to disproportionate inorganic sulfur compounds (sulfur, thiosulfate, sulfite) and to grow, although growth on sulfur required a sulfide scavenger (FeOOH). Isolate Cad16 represented small-celled purple sulfur bacteria that belonged to a previously detected, but uncultured population designated F and was related to Lamprocystis purpurea as evidenced by comparative 16S rRNA analysis and the presence of bacteriochlorophyll a and the carotenoid okenone. Mixed cultures of isolates Cad626 and Cad16 resulted in their association in aggregates similar to those observed in the chemocline of Lake Cadagno. Concomitant growth enhancement of both isolates in mixed culture suggested synergistic interactions that presumably resemble a source-sink relationship for sulfide between the sulfate-reducing bacterium growing by sulfur disproportionation and the purple sulfur bacteria acting as biotic scavenger.
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Spatio-temporal distribution of phototrophic sulfur bacteria in the chemocline of Meromictic Lake Cadagno (Switzerland).
FEMS microbiology ecology, 2003Co-Authors: Mauro Tonolla, Dittmar Hahn, Sandro Peduzzi, Raffaele PeduzziAbstract:In situ hybridization was used to study the spatio-temporal distribution of phototrophic sulfur bacteria in the permanent chemocline of Meromictic Lake Cadagno, Switzerland. At all four sampling times during the year the numerically most important phototrophic sulfur bacteria in the chemocline were small-celled purple sulfur bacteria of two yet uncultured populations designated D and F. Other small-celled purple sulfur bacteria (Amoebobacter purpureus and Lamprocystis roseopersicina) were found in numbers about one order of magnitude lower. These numbers were similar to those of large-celled purple sulfur bacteria (Chromatium okenii) and green sulfur bacteria that almost entirely consisted of Chlorobium phaeobacteroides. In March and June when low light intensities reached the chemocline, cell densities of all populations, with the exception of L. roseopersicina, were about one order of magnitude lower than in August and October when light intensities were much higher. Most populations were evenly distributed throughout the whole chemocline during March and June, while in August and October a microstratification of populations was detected suggesting specific eco-physiological adaptations of different populations of phototrophic sulfur bacteria to the steep physico-chemical gradients in the chemocline of Lake Cadagno.
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In situ analysis of sulfate-reducing bacteria related to Desulfocapsa thiozymogenes in the chemocline of Meromictic Lake Cadagno (Switzerland).
Applied and environmental microbiology, 2000Co-Authors: Mauro Tonolla, Antonella Demarta, Dittmar Hahn, Sandro Peduzzi, Raffaele PeduzziAbstract:Comparative sequence analysis of a 16S rRNA gene clone library from the chemocline of the Meromictic Lake Cadagno (Switzerland) retrieved two clusters of sequences resembling sulfate-reducing bacteria within the family Desulfovibrionaceae. In situ hybridization showed that, similar to sulfate-reducing bacteria of the family Desulfobacteriaceae, bacteria of one cluster with similarity values to the closest cultured relatives of between 92.6 and 93.1% resembled free cells or cells loosely attached to other cells or debris. Bacteria of the second cluster closely related to Desulfocapsa thiozymogenes DSM7269 with similarity values between 97.9 and 98.4% were generally associated with aggregates of different small-celled phototrophic sulfur bacteria, suggesting a potential interaction between the two groups of bacteria.
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In situ analysis of phototrophic sulfur bacteria in the chemocline of Meromictic Lake Cadagno (Switzerland).
Applied and environmental microbiology, 1999Co-Authors: Mauro Tonolla, Antonella Demarta, Raffaele Peduzzi, Dittmar HahnAbstract:Comparative sequence analysis of a 16S rRNA gene clone library from the chemocline of the Meromictic Lake Cadagno (Switzerland) revealed the presence of a diverse number of phototrophic sulfur bacteria. Sequences resembled those of rRNA of type strains Chromatium okenii DSM169 and Amoebobacter purpureus DSM4197, as well as those of four bacteria forming a tight cluster with A. purpureus DSM4197 and Lamprocystis roseopersicina DSM229. In situ hybridization with fluorescent (Cy3 labeled) oligonucleotide probes indicated that all large-celled phototrophic sulfur bacteria in the chemocline of Lake Cadagno were represented by C. okenii DSM169, while small-celled phototrophic sulfur bacteria consisted of four major populations with different distribution profiles in the chemocline indicating different ecophysiological adaptations.