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Bo Barker Jorgensen - One of the best experts on this subject based on the ideXlab platform.
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phosphate geochemistry mineralization processes and Thioploca distribution in shelf sediments off central chile
Marine Geology, 2010Co-Authors: Lars Holmkvist, Bo Barker Jorgensen, Esther T Arning, Kathrin Kusterheins, Verona Vandieken, Jorn Peckmann, Matthias ZabelAbstract:Abstract Sediments underlying the major costal upwelling systems of the world oceans are hot-spots of modern formation of hydroxyapatites, often associated with benthic communities of large, nitrate-accumulating sulfur bacteria. We studied the association between phosphate release, organic phosphorus mineralization, and occurrence of dense communities of the filamentous sulfur bacteria, Thioploca spp., on the continental shelf off central Chile during the austral summer when high phytoplankton productivity and anoxic bottom water prevailed. Freshly deposited phytodetritus stimulated extremely high sulfate reduction rates, which supported a large Thioploca community of up to 100 g biomass per m 2 . Effective bacterial sulfide uptake kept the sulfide concentration low, which enabled the accumulation of free iron, thus demonstrating intensive iron reduction concurrent with sulfate reduction. Phosphate released to the pore water reached 100–300 μM peak concentrations within the uppermost 0–5 cm and phosphate was lost to the overlying anoxic water column. The large phosphate release was not directly related to the presence of Thioploca but was rather the result of a high deposition and mineralization rate of fresh organic detritus. Although the pore water was super–saturated with respect to hydroxyapatite, this mineral was only a minor P-component in the sediment. Most solid-phase phosphate was bound to iron.
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filamentous bacteria inhabiting the sheaths of marine Thioploca spp on the chilean continental shelf
FEMS Microbiology Ecology, 2009Co-Authors: Andreas Teske, Bo Barker Jorgensen, Victor A GallardoAbstract:A new component of the benthic Thioploca mat microbial ecosystem on the Chilean continental shelf was detected by epifluorescence microscopy: filamentous, bacterial endobionts of 4–5-μm filament diameter and length sometimes exceeding 1 mm. These filaments were identified as growing within Thioploca sheaths located between the sediment surface and c . 5 cm depth. Their location coincided with maximal biomass and biovolume of Thioploca filaments in surficial sediments, and with maximal abundance and activity of sulfate-reducing bacterial populations near the sediment/water interface. FISH and environmental characteristics support the working hypothesis that these endobiont populations are members of the filamentous, sulfate-reducing bacterial genus Desulfonema . Found at several sampling stations over a decade-long interval (1994–2006), these populations appear to be a stable component of the Chilean Thioploca mat ecosystem.
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physiology and behaviour of marine Thioploca
The ISME Journal, 2009Co-Authors: Signe Hogslund, Bo Barker Jorgensen, Victor A Gallardo, Jeppe Lund Nielsen, Niels Peter Revsbech, Gijs J Kuenen, Jack Van De Vossenberg, Lars Holmkvist, Esther T ArningAbstract:Among prokaryotes, the large vacuolated marine sulphur bacteria are unique in their ability to store, transport and metabolize significant quantities of sulphur, nitrogen, phosphorus and carbon compounds. In this study, unresolved questions of metabolism, storage management and behaviour were addressed in laboratory experiments with Thioploca species collected on the continental shelf off Chile. The Thioploca cells had an aerobic metabolism with a potential oxygen uptake rate of 1760 micromol O2 per dm(3) biovolume per h, equivalent to 4.4 nmol O2 per min per mg protein. When high ambient sulphide concentrations (approximately 200 microM) were present, a sulphide uptake of 6220+/-2230 micromol H2S per dm(3) per h, (mean+/-s.e.m., n=4) was measured. This sulphide uptake rate was six times higher than the oxidation rate of elemental sulphur by oxygen or nitrate, thus indicating a rapid sulphur accumulation by Thioploca. Thioploca reduce nitrate to ammonium and we found that dinitrogen was not produced, neither through denitrification nor through anammox activity. Unexpectedly, polyphosphate storage was not detectable by microautoradiography in physiological assays or by staining and microscopy. Carbon dioxide fixation increased when nitrate and nitrite were externally available and when organic carbon was added to incubations. Sulphide addition did not increase carbon dioxide fixation, indicating that Thioploca use excess of sulphide to rapidly accumulate sulphur rather than to accelerate growth. This is interpreted as an adaptation to infrequent high sulphate reduction rates in the seabed. The physiology and behaviour of Thioploca are summarized and the adaptations to an environment, dominated by infrequent oxygen availability and periods of high sulphide abundance, are discussed.
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biogeochemistry of sulfur and iron in Thioploca colonized surface sediments in the upwelling area off central chile
Geochimica et Cosmochimica Acta, 2008Co-Authors: Jakob Zopfi, Michael E Bottcher, Bo Barker JorgensenAbstract:Abstract The biogeochemistry of sedimentary sulfur was investigated on the continental shelf off central Chile at water depths between 24 and 88 m under partial influence of an oxygen minimum zone. Dissolved and solid iron and sulfur species, including the sulfur intermediates sulfite, thiosulfate, and elemental sulfur, were analyzed at high resolution in the top 20 cm. All stations were characterized by high rates of sulfate reduction, but only the sediments within the Bay of Concepcion contained dissolved sulfide. Due to advection and/or in-situ reoxidation of sulfide, dissolved sulfate was close to bottom water values. Whereas the concentrations of sulfite and thiosulfate were mostly in the submicromolar range, elemental sulfur was by far the dominant sulfur intermediate. Although the large nitrate- and sulfur-storing bacteria Thioploca were abundant, the major part of S0 was located extracellularly. The distribution of sulfur species and dissolved iron suggests the reaction of sulfide with FeOOH as an important pathway for sulfide oxidation and sulfur intermediate formation. This is in agreement with the sulfur isotope composition of co-existing elemental sulfur and iron monosulfides. In the Bay of Concepcion, sulfur isotope data suggest that pyrite formation proceeds via the reaction of FeS with polysulfides or H2S. At the shelf stations, on the other hand, pyrite was significantly depleted in 34S relative to its potential precursors FeS and S0. Isotope mass balance considerations suggest further that pyritization at depth includes light sulfide, potentially originating from bacterial sulfur disproportionation. The δ34S-values of pyrite down to −38‰ vs. V-CDT are among the lightest found in organic-rich marine sediments. Seasonal variations in the sulfur isotope composition of dissolved sulfate indicated a dynamic non-steady-state sulfur cycle in the surface sediments. The 18O content of porewater sulfate increased with depth at all sites compared to the bottom water composition due to intracellular isotope exchange reactions during microbial sulfur transformations.
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ecology of Thioploca spp nitrate and sulfur storage in relation to chemical microgradients and influence of Thioploca spp on the sedimentary nitrogen cycle
Applied and Environmental Microbiology, 2001Co-Authors: Jakob Zopfi, Thomas Kjaer, Lars Peter Nielsen, Bo Barker JorgensenAbstract:Microsensors, including a recently developed NO3− biosensor, were applied to measure O2 and NO3− profiles in marine sediments from the upwelling area off central Chile and to investigate the influence of Thioploca spp. on the sedimentary nitrogen metabolism. The studies were performed in undisturbed sediment cores incubated in a small laboratory flume to simulate the environmental conditions of low O2, high NO3−, and bottom water current. On addition of NO3− and NO2−, Thioploca spp. exhibited positive chemotaxis and stretched out of the sediment into the flume water. In a core densely populated with Thioploca, the penetration depth of NO3− was only 0.5 mm and a sharp maximum of NO3− uptake was observed 0.5 mm above the sediment surface. In sediments with only few Thioploca spp., NO3− was detectable down to a depth of 2 mm and the maximum consumption rates were observed within the sediment. No chemotaxis toward nitrous oxide (N2O) was observed, which is consistent with the observation that Thioploca does not denitrify but reduces intracellular NO3− to NH4+. Measurements of the intracellular NO3− and S0 pools in Thioploca filaments from various depths in the sediment gave insights into possible differences in the migration behavior between the different species. Living filaments containing significant amounts of intracellular NO3− were found to a depth of at least 13 cm, providing final proof for the vertical shuttling of Thioploca spp. and nitrate transport into the sediment.
Manabu Fukui - One of the best experts on this subject based on the ideXlab platform.
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ecophysiology of Thioploca ingrica as revealed by the complete genome sequence supplemented with proteomic evidence
The ISME Journal, 2015Co-Authors: Hisaya Kojima, Fumiko Nemoto, Yoshitoshi Ogura, Nozomi Yamamoto, Tomoaki Togashi, Hiroshi Mori, Tomohiro Watanabe, Ken Kurokawa, Tetsuya Hayashi, Manabu FukuiAbstract:Large sulfur-oxidizing bacteria, which accumulate a high concentration of nitrate, are important constituents of aquatic sediment ecosystems. No representative of this group has been isolated in pure culture, and only fragmented draft genome sequences are available for these microorganisms. In this study, we successfully reconstituted the genome of Thioploca ingrica from metagenomic sequences, thereby generating the first complete genome sequence from this group. The Thioploca samples for the metagenomic analysis were obtained from a freshwater lake in Japan. A PCR-free paired-end library was constructed from the DNA extracted from the samples and was sequenced on the Illumina MiSeq platform. By closing gaps within and between the scaffolds, we obtained a circular chromosome and a plasmid-like element. The reconstituted chromosome was 4.8 Mbp in length with a 41.2% GC content. A sulfur oxidation pathway identical to that suggested for the closest relatives of Thioploca was deduced from the reconstituted genome. A full set of genes required for respiratory nitrate reduction to dinitrogen gas was also identified. We further performed a proteomic analysis of the Thioploca sample and detected many enzymes/proteins involved in sulfur oxidation, nitrate respiration and inorganic carbon fixation as major components of the protein extracts from the sample, suggesting that these metabolic activities are strongly associated with the physiology of T. ingrica in lake sediment.
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Diversity of Freshwater Thioploca Species and Their Specific Association with Filamentous Bacteria of the Phylum Chloroflexi
Microbial Ecology, 2011Co-Authors: Fumiko Nemoto, Hisaya Kojima, Manabu FukuiAbstract:Phylogenetic diversity among filamentous sulfur-oxidizing bacteria of the genus Thioploca inhabiting freshwater/brackish environments was analyzed in detail. The 16S rRNA gene sequence of Thioploca found in a freshwater lake in Japan, Lake Okotanpe, was identical to that of Thioploca from Lake Ogawara, a brackish lake. The samples of the two lakes could be differentiated by the sequences of their 23S rRNA genes and 16S–23S rRNA internal transcribed spacer (ITS) regions. The 23S rRNA-based phylogenetic relationships between Thioploca samples from four lakes (Lake Okotanpe, Lake Ogawara, Lake Biwa, and Lake Constance) were similar to those based on the 16S rRNA gene sequences. In addition, multiple types of the ITS sequences were obtained from Thioploca inhabiting Lake Okotanpe and Lake Constance. Variations within respective Thioploca populations were also observed in the analysis of the soxB gene, involved in sulfur oxidation. As major members of the sheath-associated microbial community, bacteria of the phylum Chloroflexi were consistently detected in the samples from different lakes. Fluorescence in situ hybridization revealed that they were filamentous and abundantly distributed within the sheaths of Thioploca .
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carbon source utilization and accumulation of respiration related substances by freshwater Thioploca species
FEMS Microbiology Ecology, 2007Co-Authors: Hisaya Kojima, Takuo Nakajima, Manabu FukuiAbstract:Carbon source utilization of Thioploca species from freshwater and brackish lakes in Japan was investigated. Microautoradiography demonstrated that freshwater and brackish Thioploca samples assimilate acetate. In addition, vertical nitrate transportation by freshwater Thioploca was examined by measuring substances accumulated in Thioploca filaments. The filaments of Thioploca sp. from Lake Biwa, a Japanese mesotrophic lake, contained nitrate at concentrations higher than ambient by two to three orders of magnitude. They also accumulated high concentrations of sulfate and abundant elemental sulfur. The results suggest that the Thioploca-specific strategy for sulfur oxidation, migration with accumulated nitrate, is effective even in freshwater habitats of lower sulfide supply.
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community structure of bacteria associated with sheaths of freshwater and brackish Thioploca species
Microbial Ecology, 2006Co-Authors: Hisaya Kojima, Manabu Fukui, Yoshikazu KoizumiAbstract:Bacterial communities associated with sheaths of Thioploca spp. from two freshwater lakes (Lake Biwa, Japan, and Lake Constance, Germany) and one brackish lake (Lake Ogawara, Japan) were analyzed with denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. The comparison between the DGGE band patterns of bulk sediment and Thioploca filaments of Lake Biwa suggested the presence of specific bacterial communities associated with Thioploca sheaths. As members of sheath-associated communities, bacteria belonging to Bacteroidetes were detected from the samples of both freshwater lakes. A DGGE band from Thioploca of Lake Biwa, belonging to candidate division OP8, was quite closely related to another DGGE band detected from that of Lake Constance. In contrast to the case of freshwater lakes, no bacterium of Bacteroidetes or OP8 was detected from Thioploca of Lake Ogawara. However, two DGGE bands from Lake Ogawara, belonging to Chloroflexi, were quite closely related to a DGGE band from Lake Constance. Two DGGE bands obtained from Lake Biwa were closely related to phylogenetically distant dissimilatory Fe(III)-reducing bacteria. Cloning analyses for a dissimilatory sulfite reductase gene were performed on the same samples used for DGGE analysis. The results of the analyses suggest that sheaths of freshwater/brackish Thioploca have little ecological significance for the majority of sulfate reducers.
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morphological and phylogenetic characterizations of freshwater Thioploca species from lake biwa japan and lake constance germany
Applied and Environmental Microbiology, 2003Co-Authors: Hisaya Kojima, Andreas Teske, Manabu FukuiAbstract:Filamentous, gliding, sulfide-oxidizing bacteria of the genus Thioploca were found on sediments in profundal areas of Lake Biwa, a Japanese freshwater mesotrophic lake, and were characterized morphologically and phylogenetically. The Lake Biwa Thioploca resembled morphologically Thioploca ingrica, a brackish water species from a Danish fjord. The diameters of individual trichomes were 3 to 5.6 μm; the diameters of complete Thioploca filaments ranged from 18 to 75 μm. The cell lengths ranged from 1.2 to 3.8 μm. In transmission electron microscope specimens stained with uranyl acetate, dense intracellular particles were found, which did not show any positive signals for phosphorus and sulfur in an X-ray analysis. The 16S rRNA gene of the Thioploca from Lake Biwa was amplified by using newly designed Thioploca-specific primers (706-Thioploca, Biwa160F, and Biwa829R) in combination with general bacterial primers in order to avoid nonspecific amplification of contaminating bacterial DNA. Denaturing gradient gel electrophoresis (DGGE) analysis of the three overlapping PCR products resulted in single DGGE bands, indicating that a single 16S rRNA gene had been amplified. With the same method, the Thioploca from Lake Constance was examined. The 16S rRNA sequence was verified by performing fluorescence in situ hybridization targeted at specific motifs of the Lake Biwa Thioploca. Positive signals were obtained with the bacterial probe EUB-338, the γ-proteobacterial probe GAM42a, and probe Biwa829 targeting the Lake Biwa Thioploca. Based on the nearly complete 16S rRNA sequence and on morphological similarities, the Thioploca from Lake Biwa and the Thioploca from Lake Constance are closely related to T. ingrica and to each other.
Henrik Fossing - One of the best experts on this subject based on the ideXlab platform.
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vertical migration in the sediment dwelling sulfur bacteria Thioploca spp in overcoming diffusion limitations
Applied and Environmental Microbiology, 1996Co-Authors: Markus Huettel, Stefan Forster, S Kloser, Henrik FossingAbstract:In order to investigate the environmental requirements of the filamentous sulfur bacteria Thioploca spp., we tested the chemotactic responses of these sedimentary microorganisms to changes in oxygen, nitrate, and sulfide concentrations. A sediment core with a Thioploca mat, retrieved from the oxygen-minimum zone on the Chilean shelf, was incubated in a recirculating flume. The addition of 25 (mu)mol of nitrate per liter to the seawater flow induced the ascent of the Thioploca trichomes (length, up to 70 mm) in their mostly vertically oriented gelatinous sheaths. The upper ends of the filaments penetrated the sediment surface and protruded 1 to 3 mm into the flowing water before they bent downstream. By penetrating the diffusive boundary layer, Thioploca spp. facilitate efficient nitrate uptake in exposed trichome sections that are up to 30 mm long. The cumulative length of exposed filaments per square centimeter of sediment surface was up to 92 cm, with a total exposed trichome surface area of 1 cm(sup2). The positive reaction to nitrate overruled a negative response to oxygen, indicating that nitrate is the principal electron acceptor used by Thioploca spp. in the anoxic environment; 10-fold increases in nitrate fluxes after massive emergence of filaments strengthened this hypothesis. A positive chemotactic response to sulfide concentrations of less than 100 (mu)mol liter(sup-1) counteracted the attraction to nitrate and, along with phobic reactions to oxygen and higher sulfide concentrations, controlled the vertical movement of the trichomes. We suggest that the success of Thioploca spp. on the Chilean shelf is based on the ability of these organisms to shuttle between the nitrate-rich boundary layer and the sulfidic sediment strata.
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community structure of filamentous sheath building sulfur bacteria Thioploca spp off the coast of chile
Applied and Environmental Microbiology, 1996Co-Authors: Heide N Schulz, Bo Barker Jorgensen, Henrik Fossing, Niels B. RamsingAbstract:The filamentous sulfur bacteria Thioploca spp. produce dense bacterial mats in the shelf area off the coast of Chile and Peru. The mat consists of common sheaths, shared by many filaments, that reach 5 to 10 cm down into the sediment. The structure of the Thioploca communities off the Bay of Concepcion was investigated with respect to biomass, species distribution, and three-dimensional orientation of the sheaths. Thioploca sheaths and filaments were found across the whole shelf area within the oxygen minimum zone. The maximum wet weight of sheaths, 800 g m(sup-2), was found at a depth of 90 m. The bacterial filaments within the sheaths contributed about 10% of this weight. The highest density of filaments was found within the uppermost 1 cm of the mat. On the basis of diameter classes, it was possible to distinguish populations containing only Thioploca spp. from mixed populations containing Beggiatoa spp. Three distinct size classes of Thioploca spp. were found, two of which have been described previously as Thioploca araucae and Thioploca chileae. Many Thioploca filaments did not possess a visible sheath, and about 20% of the sheaths contained more than one Thioploca species. The three-dimensional sheath structure showed that Thioploca filaments can move from the surface and deep into the sediment.
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Phylogeny of Thioploca and Related Filamentous Sulfide-Oxidizing Bacteria
Systematic and Applied Microbiology, 1995Co-Authors: Andreas P Teske, Niels B. Ramsing, Jan Küver, Henrik FossingAbstract:Summary The phylogenetic relationships of three Thioploca species, T. araucae , T. chileae and T. ingrica , as well as Beggiatoa alba , Beggiatoa sp. str 1401-13, and Thiothrix nivea were determined by 16S rRNA sequence analysis. Fluorescent in situ hybridization with Thioploca -specific oligonucleotide probes was used to substantiate the sequences of T. araucae and T. chileae . All three Thioploca species form a monophyletic group. They are affiliated with Beggiatoa alba and Beggiatoa sp. str 1401-13. Thioploca and Beggiatoa constitute a new phylogenetic lineage within the gamma-subdivision of the proteobacteria, showing similar genetic diversity as other major groups of gamma- or beta-subdivision sulfur oxidizers. Thiothrix nivea is a member of the gamma proteobacteria, but does not form a monophyletic lineage with Beggiatoa and Thioploca .
Victor A Gallardo - One of the best experts on this subject based on the ideXlab platform.
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filamentous bacteria inhabiting the sheaths of marine Thioploca spp on the chilean continental shelf
FEMS Microbiology Ecology, 2009Co-Authors: Andreas Teske, Bo Barker Jorgensen, Victor A GallardoAbstract:A new component of the benthic Thioploca mat microbial ecosystem on the Chilean continental shelf was detected by epifluorescence microscopy: filamentous, bacterial endobionts of 4–5-μm filament diameter and length sometimes exceeding 1 mm. These filaments were identified as growing within Thioploca sheaths located between the sediment surface and c . 5 cm depth. Their location coincided with maximal biomass and biovolume of Thioploca filaments in surficial sediments, and with maximal abundance and activity of sulfate-reducing bacterial populations near the sediment/water interface. FISH and environmental characteristics support the working hypothesis that these endobiont populations are members of the filamentous, sulfate-reducing bacterial genus Desulfonema . Found at several sampling stations over a decade-long interval (1994–2006), these populations appear to be a stable component of the Chilean Thioploca mat ecosystem.
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physiology and behaviour of marine Thioploca
The ISME Journal, 2009Co-Authors: Signe Hogslund, Bo Barker Jorgensen, Victor A Gallardo, Jeppe Lund Nielsen, Niels Peter Revsbech, Gijs J Kuenen, Jack Van De Vossenberg, Lars Holmkvist, Esther T ArningAbstract:Among prokaryotes, the large vacuolated marine sulphur bacteria are unique in their ability to store, transport and metabolize significant quantities of sulphur, nitrogen, phosphorus and carbon compounds. In this study, unresolved questions of metabolism, storage management and behaviour were addressed in laboratory experiments with Thioploca species collected on the continental shelf off Chile. The Thioploca cells had an aerobic metabolism with a potential oxygen uptake rate of 1760 micromol O2 per dm(3) biovolume per h, equivalent to 4.4 nmol O2 per min per mg protein. When high ambient sulphide concentrations (approximately 200 microM) were present, a sulphide uptake of 6220+/-2230 micromol H2S per dm(3) per h, (mean+/-s.e.m., n=4) was measured. This sulphide uptake rate was six times higher than the oxidation rate of elemental sulphur by oxygen or nitrate, thus indicating a rapid sulphur accumulation by Thioploca. Thioploca reduce nitrate to ammonium and we found that dinitrogen was not produced, neither through denitrification nor through anammox activity. Unexpectedly, polyphosphate storage was not detectable by microautoradiography in physiological assays or by staining and microscopy. Carbon dioxide fixation increased when nitrate and nitrite were externally available and when organic carbon was added to incubations. Sulphide addition did not increase carbon dioxide fixation, indicating that Thioploca use excess of sulphide to rapidly accumulate sulphur rather than to accelerate growth. This is interpreted as an adaptation to infrequent high sulphate reduction rates in the seabed. The physiology and behaviour of Thioploca are summarized and the adaptations to an environment, dominated by infrequent oxygen availability and periods of high sulphide abundance, are discussed.
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population study of the filamentous sulfur bacteria Thioploca spp off the bay of concepcion chile
Marine Ecology Progress Series, 2000Co-Authors: Heide N Schulz, Victor A Gallardo, Bettina Strotmann, Bo Barker JorgensenAbstract:A population of filamentous sulfur bacteria Thioploca spp. living in the Bay of Concep- ci6n, Chile, and the adjoining shelf area was sampled for 14 mo at 4 to 6 wk intervals to investigate the influence of seasonal variations in upwelhg intensity and oxygen concentrations on the popula- tion dynamics. The Thioploca population was described by its biomass, total number and diameter of sheaths, number of trichomes and species per sheath, and abundance and depth distribution of dif- ferent morphological forms, e.g. trichome diameters and ratios of cell-length to diameter. Throughout the summer of 1996, oxygen concentrations in the bottom water were near zero, nitrate was 10 to 20 pM and the biomass was high, up to 160 g m-' wet weight without sheaths. During winter, the bio- mass declined due to higher oxygen concentrations under reduced upwelling intensity. The depth distribution of Thioploca spp. changed strongly with seasonal variations, but the population structure remained mainly unchanged. During the 'El Nifio' event in 1998, with high oxygen and low primary production, the biomass was very low. In the Bay of Concepcion 2 populations of filamentous sulfur bacteria were observed, filaments with short cells in sheaths, populating the upper 7 cm of the sedi- ment, and filaments without sheaths living at the sediment surface.
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nitrogen carbon and sulfur metabolism in natural Thioploca samples
Applied and Environmental Microbiology, 1999Co-Authors: S Otte, Victor A Gallardo, Andreas Teske, Heide N Schulz, Jakob Zopfi, Lars Peter Nielsen, J G Kuenen, Hans W Paerl, Bettina Strotmann, Bo Barker JorgensenAbstract:Filamentous sulfur bacteria of the genus Thioploca occur as dense mats on the continental shelf off the coast of Chile and Peru. Since little is known about their nitrogen, sulfur, and carbon metabolism, this study was undertaken to investigate their (eco)physiology. Thioploca is able to store internally high concentrations of sulfur globules and nitrate. It has been previously hypothesized that these large vacuolated bacteria can oxidize sulfide by reducing their internally stored nitrate. We examined this nitrate reduction by incubation experiments of washed Thioploca sheaths with trichomes in combination with 15N compounds and mass spectrometry and found that these Thioploca samples produce ammonium at a rate of 1 nmol min-1 mg of protein-1. Controls showed no significant activity. Sulfate was shown to be the end product of sulfide oxidation and was observed at a rate of 2 to 3 nmol min-1 mg of protein-1. The ammonium and sulfate production rates were not influenced by the addition of sulfide, suggesting that sulfide is first oxidized to elemental sulfur, and in a second independent step elemental sulfur is oxidized to sulfate. The average sulfide oxidation rate measured was 5 nmol min-1 mg of protein-1 and could be increased to 10.7 nmol min-1 mg of protein-1 after the trichomes were starved for 45 h. Incorporation of 14CO2 was at a rate of 0.4 to 0.8 nmol min-1 mg of protein-1, which is half the rate calculated from sulfide oxidation. [2-14C]acetate incorporation was 0.4 nmol min-1 mg of protein-1, which is equal to the CO2 fixation rate, and no 14CO2 production was detected. These results suggest that Thioploca species are facultative chemolithoautotrophs capable of mixotrophic growth. Microautoradiography confirmed that Thioploca cells assimilated the majority of the radiocarbon from [2-14C]acetate, with only a minor contribution by epibiontic bacteria present in the samples.
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Thioploca spp filamentous sulfur bacteria with nitrate vacuoles
FEMS Microbiology Ecology, 1999Co-Authors: Bo Barker Jorgensen, Victor A GallardoAbstract:Thioploca spp. are multicellular, filamentous, colorless sulfur bacteria inhabiting freshwater and marine sediments. They have elemental sulfur inclusions similar to the phylogenetically closely related Beggiatoa, but in contrast to these they live in bundles surrounded by a common sheath. Vast communities of large Thioploca species live along the Pacific coast of South America and in other upwelling areas of high organic matter sedimentation with bottom waters poor in oxygen and rich in nitrate. Each cell of these Thioplocas harbors a large liquid vacuole which is used as a storage for nitrate with a concentration of up to 500 mM. The nitrate is used as an electron acceptor for sulfide oxidation and the bacteria may grow autotrophically or mixotrophically using acetate or other organic molecules as carbon source. The filaments stretch up into the overlying seawater, from which they take up nitrate, and then glide down 5–15 cm deep into the sediment through their sheaths to oxidize sulfide formed by intensive sulfate reduction. New major occurrences have been found in recent years, both in lakes and in the ocean, and have stimulated the interest in these fascinating bacteria.
Heide N Schulz - One of the best experts on this subject based on the ideXlab platform.
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population study of the filamentous sulfur bacteria Thioploca spp off the bay of concepcion chile
Marine Ecology Progress Series, 2000Co-Authors: Heide N Schulz, Victor A Gallardo, Bettina Strotmann, Bo Barker JorgensenAbstract:A population of filamentous sulfur bacteria Thioploca spp. living in the Bay of Concep- ci6n, Chile, and the adjoining shelf area was sampled for 14 mo at 4 to 6 wk intervals to investigate the influence of seasonal variations in upwelhg intensity and oxygen concentrations on the popula- tion dynamics. The Thioploca population was described by its biomass, total number and diameter of sheaths, number of trichomes and species per sheath, and abundance and depth distribution of dif- ferent morphological forms, e.g. trichome diameters and ratios of cell-length to diameter. Throughout the summer of 1996, oxygen concentrations in the bottom water were near zero, nitrate was 10 to 20 pM and the biomass was high, up to 160 g m-' wet weight without sheaths. During winter, the bio- mass declined due to higher oxygen concentrations under reduced upwelling intensity. The depth distribution of Thioploca spp. changed strongly with seasonal variations, but the population structure remained mainly unchanged. During the 'El Nifio' event in 1998, with high oxygen and low primary production, the biomass was very low. In the Bay of Concepcion 2 populations of filamentous sulfur bacteria were observed, filaments with short cells in sheaths, populating the upper 7 cm of the sedi- ment, and filaments without sheaths living at the sediment surface.
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nitrogen carbon and sulfur metabolism in natural Thioploca samples
Applied and Environmental Microbiology, 1999Co-Authors: S Otte, Victor A Gallardo, Andreas Teske, Heide N Schulz, Jakob Zopfi, Lars Peter Nielsen, J G Kuenen, Hans W Paerl, Bettina Strotmann, Bo Barker JorgensenAbstract:Filamentous sulfur bacteria of the genus Thioploca occur as dense mats on the continental shelf off the coast of Chile and Peru. Since little is known about their nitrogen, sulfur, and carbon metabolism, this study was undertaken to investigate their (eco)physiology. Thioploca is able to store internally high concentrations of sulfur globules and nitrate. It has been previously hypothesized that these large vacuolated bacteria can oxidize sulfide by reducing their internally stored nitrate. We examined this nitrate reduction by incubation experiments of washed Thioploca sheaths with trichomes in combination with 15N compounds and mass spectrometry and found that these Thioploca samples produce ammonium at a rate of 1 nmol min-1 mg of protein-1. Controls showed no significant activity. Sulfate was shown to be the end product of sulfide oxidation and was observed at a rate of 2 to 3 nmol min-1 mg of protein-1. The ammonium and sulfate production rates were not influenced by the addition of sulfide, suggesting that sulfide is first oxidized to elemental sulfur, and in a second independent step elemental sulfur is oxidized to sulfate. The average sulfide oxidation rate measured was 5 nmol min-1 mg of protein-1 and could be increased to 10.7 nmol min-1 mg of protein-1 after the trichomes were starved for 45 h. Incorporation of 14CO2 was at a rate of 0.4 to 0.8 nmol min-1 mg of protein-1, which is half the rate calculated from sulfide oxidation. [2-14C]acetate incorporation was 0.4 nmol min-1 mg of protein-1, which is equal to the CO2 fixation rate, and no 14CO2 production was detected. These results suggest that Thioploca species are facultative chemolithoautotrophs capable of mixotrophic growth. Microautoradiography confirmed that Thioploca cells assimilated the majority of the radiocarbon from [2-14C]acetate, with only a minor contribution by epibiontic bacteria present in the samples.
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community structure of filamentous sheath building sulfur bacteria Thioploca spp off the coast of chile
Applied and Environmental Microbiology, 1996Co-Authors: Heide N Schulz, Bo Barker Jorgensen, Henrik Fossing, Niels B. RamsingAbstract:The filamentous sulfur bacteria Thioploca spp. produce dense bacterial mats in the shelf area off the coast of Chile and Peru. The mat consists of common sheaths, shared by many filaments, that reach 5 to 10 cm down into the sediment. The structure of the Thioploca communities off the Bay of Concepcion was investigated with respect to biomass, species distribution, and three-dimensional orientation of the sheaths. Thioploca sheaths and filaments were found across the whole shelf area within the oxygen minimum zone. The maximum wet weight of sheaths, 800 g m(sup-2), was found at a depth of 90 m. The bacterial filaments within the sheaths contributed about 10% of this weight. The highest density of filaments was found within the uppermost 1 cm of the mat. On the basis of diameter classes, it was possible to distinguish populations containing only Thioploca spp. from mixed populations containing Beggiatoa spp. Three distinct size classes of Thioploca spp. were found, two of which have been described previously as Thioploca araucae and Thioploca chileae. Many Thioploca filaments did not possess a visible sheath, and about 20% of the sheaths contained more than one Thioploca species. The three-dimensional sheath structure showed that Thioploca filaments can move from the surface and deep into the sediment.
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concentration and transport of nitrate by the mat forming sulphur bacterium Thioploca
Nature, 1995Co-Authors: Henrik Fossing, Bo Barker Jorgensen, Victor A Gallardo, Heide N Schulz, Lars Peter Nielsen, Markus Huttel, Donald E Canfield, S Forster, Ronnie N Glud, Jens K GundersenAbstract:MARINE species of Thioploca occur over 3,000 km along the continental shelf off Southern Peru and North and Central Chile1–4. These filamentous bacteria live in bundles surrounded by a common sheath and form thick mats on the sea floor under the oxygen-minimum zone in the upwelling region, at between 40 and 280 m water depth. The metabolism of this marine bacterium5,6 remained a mystery until long after its discovery1,7. We report here that Thioploca cells are able to concentrate nitrate to up to 500 mM in a liquid vacuole that occupies >80% of the cell volume. Gliding filaments transport this nitrate 5–10 cm down into the sediment and reduce it, with concomitant oxidation of hydrogen sulphide, thereby coupling the nitrogen and sulphur cycles in the sediment.