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Hans-dietrich Babenzien - One of the best experts on this subject based on the ideXlab platform.
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Vertical distribution of sulfate-reducing bacteria at the Oxic-anOxic interface in Sediments of the oligotrophic Lake Stechlin
FEMS Microbiology Ecology, 2006Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich BabenzienAbstract:Vertical distribution of sulfate-reducing bacteria (SRB) and sulfate reduction rates were investigated in littoral and profundal Sediments of the oligotrophic Lake Stechlin. SRB counted by the most probable number (MPN) technique showed two peaks, one at the Oxic-anOxic interface, and the second deeper in the reduced Sediment layer. Sulfate reduction rates determined as potential rates in anOxic Sediment slurries showed a similar vertical distribution with the highest values in the anOxic zones. The highest cell numbers observed were 1.3×105 cells cm−3 with lactate as substrate. SRB were also found in Oxic Sediment layers in numbers similar to those detected in anOxic zones. From the highest positive MPN tubes 34 pure cultures were isolated. Physiological characterization including nutritional behaviour, tests for desulfoviridin and spore formation turned out that nearly all isolates belonged to the genera Desulfovibrio, Desulfomicrobium, and Desulfotomaculum. SRB from the Oxic Sediment layers revealed a higher oxygen tolerance and capacity of oxygen respiration than isolates from the anOxic Sediment layers. However, no sulfate reduction was observed in the presence of oxygen, since oxygen was preferentially reduced.
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High genetic and physiological diversity of sulfate-reducing bacteria isolated from an oligotrophic lake Sediment
Archives of Microbiology, 1998Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich Babenzien, Elze B. A. Wieringa, Joerg OvermannAbstract:The community structure of sulfate-reducing bacteria in littoral and profundal Sediments of the oligotrophic Lake Stechlin (Germany) was investigated. A collection of 32 strains was isolated from the highest positive dilutions of most-probable-number series, and their partial 16S rRNA gene sequences and genomic fingerprints based on ERIC (enterobacterial repetitive intergenic consensus)-PCR were analyzed. The strains fell into eight distinct phylogenetic lineages, and the majority (70%) showed a close affiliation to the genus Desulfovibrio. Most of the remaining strains (22%) were related to the gram-positive Sporomusa and Desulfotomaculum groups. A high redundancy of 16S rRNA gene sequences was found within several of the phylogenetic lineages. This low phylogenetic diversity was most pronounced for the subset of strains isolated from Oxic Sediment layers. ERIC-PCR revealed that most of the strains with identical 16S rRNA gene sequences were genetically different. Since strains with identical 16S rRNA gene sequences but different genomic fingerprints also differed considerably with respect to their physiological capabilities, the high diversity detected in the present work is very likely of ecological relevance. Our results indicate that a high diversity of sulfate-reducing bacterial strains can be recovered from the natural environment using the established cultivation media.
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Sulfate-reducing bacteria from the Oxic Sediment layers of the oligotrophic Lake Stechlin
1996Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich BabenzienAbstract:Vertical distribution of sulfate-reducing bacteria (SRB) in littoral Sediments of the oligotrophic Lake Stechlin was investigated. In this lake an Oxic Sediment layer of 5-10 mm thickness was present throughout the year. The numbers of SRB in the Oxic Sediment layers were nearly as high as in the anOxic Sediment layers and reached up to 0.75 · 105 cells/cm3. From the different Sediment layers 13 pure cultures of sulfate-reducing bacteria were isolated from the highest dilution steps in MPN series. The strains from Oxic zones differed from those of the deeper layers by a higher oxygen tolerance, a broader spectrum of substrates oxidized with O2, and by the presence of high catalase activity. Growth in the presence of oxygen was not observed.
Heribert Cypionka - One of the best experts on this subject based on the ideXlab platform.
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Vertical distribution of sulfate-reducing bacteria at the Oxic-anOxic interface in Sediments of the oligotrophic Lake Stechlin
FEMS Microbiology Ecology, 2006Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich BabenzienAbstract:Vertical distribution of sulfate-reducing bacteria (SRB) and sulfate reduction rates were investigated in littoral and profundal Sediments of the oligotrophic Lake Stechlin. SRB counted by the most probable number (MPN) technique showed two peaks, one at the Oxic-anOxic interface, and the second deeper in the reduced Sediment layer. Sulfate reduction rates determined as potential rates in anOxic Sediment slurries showed a similar vertical distribution with the highest values in the anOxic zones. The highest cell numbers observed were 1.3×105 cells cm−3 with lactate as substrate. SRB were also found in Oxic Sediment layers in numbers similar to those detected in anOxic zones. From the highest positive MPN tubes 34 pure cultures were isolated. Physiological characterization including nutritional behaviour, tests for desulfoviridin and spore formation turned out that nearly all isolates belonged to the genera Desulfovibrio, Desulfomicrobium, and Desulfotomaculum. SRB from the Oxic Sediment layers revealed a higher oxygen tolerance and capacity of oxygen respiration than isolates from the anOxic Sediment layers. However, no sulfate reduction was observed in the presence of oxygen, since oxygen was preferentially reduced.
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Detection of abundant sulphate-reducing bacteria in marine Oxic Sediment layers by a combined cultivation and molecular approach.
Environmental Microbiology, 2000Co-Authors: Elze B. A. Wieringa, Jörg Overmann, Heribert CypionkaAbstract:The depth distribution and diversity of sulphate-reducing bacteria (SRB) was analysed in the upper intertidal zone of a sandy marine Sediment of the Dutch island Schiermonnikoog. The upper centimetre of the Sediment included the Oxic-anOxic interface and was cut into five slices. With each slice, most probable number (MPN) dilution series were set up in microtitre plates using five different substrates. In the deeper Sediment layers, up to 1 x 10(8) cm(-3) lactate-utilizing SRB were counted, corresponding to 23% of the total bacterial count. From the highest positive dilutions of the MPN series, 27 strains of SRB were isolated in pure culture. Sequencing of a 580 bp fragment of the 16S rDNA revealed that 21 isolates had identical sequences, also identical with that of the previously described species Desulfomicrobium apsheronum. However, the diversity of the isolates was higher with respect to their physiological properties: a total of 11 different phenotypes could be distinguished. Genomic fingerprinting by enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction (PCR) revealed an even higher diversity of 22 different genotypes. A culture-independent analysis by PCR and denaturing-gradient gel electrophoresis (DGGE) revealed that the partial 16S rDNA sequence of the isolated D. apsheronum strains constituted a significant fraction of the Desulfovibrionaceae. The high subspecies diversity suggests that this abundant aggregate-forming species may have evolved adaptations to different ecological niches in the Oxic Sediment layers.
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High genetic and physiological diversity of sulfate-reducing bacteria isolated from an oligotrophic lake Sediment
Archives of Microbiology, 1998Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich Babenzien, Elze B. A. Wieringa, Joerg OvermannAbstract:The community structure of sulfate-reducing bacteria in littoral and profundal Sediments of the oligotrophic Lake Stechlin (Germany) was investigated. A collection of 32 strains was isolated from the highest positive dilutions of most-probable-number series, and their partial 16S rRNA gene sequences and genomic fingerprints based on ERIC (enterobacterial repetitive intergenic consensus)-PCR were analyzed. The strains fell into eight distinct phylogenetic lineages, and the majority (70%) showed a close affiliation to the genus Desulfovibrio. Most of the remaining strains (22%) were related to the gram-positive Sporomusa and Desulfotomaculum groups. A high redundancy of 16S rRNA gene sequences was found within several of the phylogenetic lineages. This low phylogenetic diversity was most pronounced for the subset of strains isolated from Oxic Sediment layers. ERIC-PCR revealed that most of the strains with identical 16S rRNA gene sequences were genetically different. Since strains with identical 16S rRNA gene sequences but different genomic fingerprints also differed considerably with respect to their physiological capabilities, the high diversity detected in the present work is very likely of ecological relevance. Our results indicate that a high diversity of sulfate-reducing bacterial strains can be recovered from the natural environment using the established cultivation media.
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Sulfate-reducing bacteria from the Oxic Sediment layers of the oligotrophic Lake Stechlin
1996Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich BabenzienAbstract:Vertical distribution of sulfate-reducing bacteria (SRB) in littoral Sediments of the oligotrophic Lake Stechlin was investigated. In this lake an Oxic Sediment layer of 5-10 mm thickness was present throughout the year. The numbers of SRB in the Oxic Sediment layers were nearly as high as in the anOxic Sediment layers and reached up to 0.75 · 105 cells/cm3. From the different Sediment layers 13 pure cultures of sulfate-reducing bacteria were isolated from the highest dilution steps in MPN series. The strains from Oxic zones differed from those of the deeper layers by a higher oxygen tolerance, a broader spectrum of substrates oxidized with O2, and by the presence of high catalase activity. Growth in the presence of oxygen was not observed.
Henrik Sass - One of the best experts on this subject based on the ideXlab platform.
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Vertical distribution of sulfate-reducing bacteria at the Oxic-anOxic interface in Sediments of the oligotrophic Lake Stechlin
FEMS Microbiology Ecology, 2006Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich BabenzienAbstract:Vertical distribution of sulfate-reducing bacteria (SRB) and sulfate reduction rates were investigated in littoral and profundal Sediments of the oligotrophic Lake Stechlin. SRB counted by the most probable number (MPN) technique showed two peaks, one at the Oxic-anOxic interface, and the second deeper in the reduced Sediment layer. Sulfate reduction rates determined as potential rates in anOxic Sediment slurries showed a similar vertical distribution with the highest values in the anOxic zones. The highest cell numbers observed were 1.3×105 cells cm−3 with lactate as substrate. SRB were also found in Oxic Sediment layers in numbers similar to those detected in anOxic zones. From the highest positive MPN tubes 34 pure cultures were isolated. Physiological characterization including nutritional behaviour, tests for desulfoviridin and spore formation turned out that nearly all isolates belonged to the genera Desulfovibrio, Desulfomicrobium, and Desulfotomaculum. SRB from the Oxic Sediment layers revealed a higher oxygen tolerance and capacity of oxygen respiration than isolates from the anOxic Sediment layers. However, no sulfate reduction was observed in the presence of oxygen, since oxygen was preferentially reduced.
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High genetic and physiological diversity of sulfate-reducing bacteria isolated from an oligotrophic lake Sediment
Archives of Microbiology, 1998Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich Babenzien, Elze B. A. Wieringa, Joerg OvermannAbstract:The community structure of sulfate-reducing bacteria in littoral and profundal Sediments of the oligotrophic Lake Stechlin (Germany) was investigated. A collection of 32 strains was isolated from the highest positive dilutions of most-probable-number series, and their partial 16S rRNA gene sequences and genomic fingerprints based on ERIC (enterobacterial repetitive intergenic consensus)-PCR were analyzed. The strains fell into eight distinct phylogenetic lineages, and the majority (70%) showed a close affiliation to the genus Desulfovibrio. Most of the remaining strains (22%) were related to the gram-positive Sporomusa and Desulfotomaculum groups. A high redundancy of 16S rRNA gene sequences was found within several of the phylogenetic lineages. This low phylogenetic diversity was most pronounced for the subset of strains isolated from Oxic Sediment layers. ERIC-PCR revealed that most of the strains with identical 16S rRNA gene sequences were genetically different. Since strains with identical 16S rRNA gene sequences but different genomic fingerprints also differed considerably with respect to their physiological capabilities, the high diversity detected in the present work is very likely of ecological relevance. Our results indicate that a high diversity of sulfate-reducing bacterial strains can be recovered from the natural environment using the established cultivation media.
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Sulfate-reducing bacteria from the Oxic Sediment layers of the oligotrophic Lake Stechlin
1996Co-Authors: Henrik Sass, Heribert Cypionka, Hans-dietrich BabenzienAbstract:Vertical distribution of sulfate-reducing bacteria (SRB) in littoral Sediments of the oligotrophic Lake Stechlin was investigated. In this lake an Oxic Sediment layer of 5-10 mm thickness was present throughout the year. The numbers of SRB in the Oxic Sediment layers were nearly as high as in the anOxic Sediment layers and reached up to 0.75 · 105 cells/cm3. From the different Sediment layers 13 pure cultures of sulfate-reducing bacteria were isolated from the highest dilution steps in MPN series. The strains from Oxic zones differed from those of the deeper layers by a higher oxygen tolerance, a broader spectrum of substrates oxidized with O2, and by the presence of high catalase activity. Growth in the presence of oxygen was not observed.
Thomas Höpner - One of the best experts on this subject based on the ideXlab platform.
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Denitrification in intertidal black anOxic surface Sediments forms rather N_2O and nitrite instead of molecular nitrogen
Senckenbergiana maritima, 2000Co-Authors: Gholamhossein Ebrahimipour, Petra Lindenlaub, Thomas HöpnerAbstract:During the “Black Area Event” of June/July 1996 in the Ostfriesian Wadden Sea, many square kilometers of the intertidal zone in the Ostfriesian Wadden Sea (Southern North Sea, Germany) lost the Oxic Sediment cover and showed a black surface of sulfidic Sediment. This and earlier work on smaller “Black Spots” caused reason to examine the effects on crucial ecological functions such as denitrification in the Sediments. This was done by examining the denitrification potential defined as a measured microbial denitrification activity which develops in a biologically active Sediment sample after a non-limiting addition of nitrate and/or organic electron donors. Four types of Sediment samples were examined: Black surface, black Sediment from below a black surface, Oxic surface Sediment from a reference area and black Sediment from below this Oxic Sediment. The Oxic sample showed the highest activity. In the presence of added electron donors, added nitrate was completely converted to N_2 within about 15 days. Transient N_2O did not or only in traces appear which later were reduced to N_2. In corresponding experiments with samples from the Black Spot (surface and depth) and black Sediments from below the Oxic cover nitrate was also converted to gaseous products. After about 7 days nearly 80% of the nitrate-N appeared as N_2O and after 45 days the ratio between N_2O-N and N_2-N was still between 1:1 and 2:1, representing together 100% of the added N. While a change of the temperature from 20 to 30°C mainly resulted in a faster conversion rate and not so much in a different intermediate and product spectrum, a change to 7°C led to an accumulation of nitrite which only in the Oxic Sediment samples was converted to N_2. The main result is that the transition of the surface Sediment from Oxic to sulfidic means a shift from the denitrification end product N_2 to partially reduced ones such as nitrite and N_2O.
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Denitrification in intertidal black anOxic surface Sediments forms rather N2O and nitrite instead of molecular nitrogen
Senckenbergiana Maritima, 2000Co-Authors: Gholamhossein Ebrahimipour, Petra Lindenlaub, Thomas HöpnerAbstract:During the “Black Area Event” of June/July 1996 in the Ostfriesian Wadden Sea, many square kilometers of the intertidal zone in the Ostfriesian Wadden Sea (Southern North Sea, Germany) lost the Oxic Sediment cover and showed a black surface of sulfidic Sediment. This and earlier work on smaller “Black Spots” caused reason to examine the effects on crucial ecological functions such as denitrification in the Sediments. This was done by examining the denitrification potential defined as a measured microbial denitrification activity which develops in a biologically active Sediment sample after a non-limiting addition of nitrate and/or organic electron donors. Four types of Sediment samples were examined: Black surface, black Sediment from below a black surface, Oxic surface Sediment from a reference area and black Sediment from below this Oxic Sediment. The Oxic sample showed the highest activity. In the presence of added electron donors, added nitrate was completely converted to N2 within about 15 days. Transient N2O did not or only in traces appear which later were reduced to N2. In corresponding experiments with samples from the Black Spot (surface and depth) and black Sediments from below the Oxic cover nitrate was also converted to gaseous products. After about 7 days nearly 80% of the nitrate-N appeared as N2O and after 45 days the ratio between N2O-N and N2-N was still between 1:1 and 2:1, representing together 100% of the added N. While a change of the temperature from 20 to 30°C mainly resulted in a faster conversion rate and not so much in a different intermediate and product spectrum, a change to 7°C led to an accumulation of nitrite which only in the Oxic Sediment samples was converted to N2. The main result is that the transition of the surface Sediment from Oxic to sulfidic means a shift from the denitrification end product N2 to partially reduced ones such as nitrite and N2O.
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“Denitrification” of nitrous oxide in anOxic intertidal Sediments
Senckenbergiana maritima, 2000Co-Authors: Gholamhossein Ebrahimipour, Petra Lindenlaub, Thomas HöpnerAbstract:In closed-bottle experiments to test the denitrification potentials of intertidal Sediments, anOxic (black, sulfidic) samples formed preferentially nitrous oxide when stimulated by addition of nitrate and a mixture of organic electron donors. Since the experiments showed fiat the formed N_2O was slowly further reduced as soon as nitrate was no longer present, N_2O was used as a substrate to be “denitrified” in the presence and absence of the electron donors. The N_2O reduction rate was very similar in four different samples: an Oxic sample from the surface, an anOxic one from below this Oxic Sediment, an anOxic one from the surface of a Black Spot (showing black sulfidic Sediment at the surface) and finally an anOxic sample from the depth below the Black spot. The reduction rates were about 15% of the corresponding nitrate reduction rates. Compared with reductions without electron donors (but in the presence of endogenous organic carbon), the addition of the electron donor mixture stimulated the rates three-to four-fold. The results show that under distinct conditions anOxic Sediments are able to form a sink for N_2O, while under different conditions (e. g. presence of nitrate) the same Sediments are N_2O sources.
Dirk De Beer - One of the best experts on this subject based on the ideXlab platform.
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Chimney construction by Chironomus riparius larvae in response to hypoxia: microbial implications for freshwater Sediments
2009Co-Authors: Peter Stief, Max Planck, Larisa Nazarova, Dirk De BeerAbstract:Many shallow aquatic ecosystems with high nutrient loads experience periods of O2 depletion that evoke behavioral responses by macrobenthic organisms. The Sediment-dwelling midge larva Chironomus riparius reduces its deposit-feeding activity and allocates more time to burrow ven- tilation during periods of hypoxia. We investigated another striking behavioral adaptation of this species, i.e., the elongation of U-shaped Sediment burrows to chimneys that tower above the Sediment surface. Chironomus riparius larvae gradually abandoned burrow construction and took up chimney construction when exposed to hypOxic conditions in laboratory microcosms. Microsensors were used to show that the chimneys were Oxic Sediment compartments that were periodically irrigated by the larvae with oxygenated surface water. O2 uptake rates per unit interface area were significantly higher for chimneys than for the flat Sediment surface. This observation was consistent with the dense colonization of the chimneys by bacteria. Chimneys may facilitate the larval acquisition of both O2 for respiration and microbial biomass for food. Given the mass abundance of C. riparius in many polluted and O2-deficient habitats, the chimneys also may contribute significantly to the patchiness of the benthic microbial community in terms of structure and function. In particular, the presence of chimneys might favor aerobic bacterial populations and their metabolism.
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Nitrate, nitrite, and nitrous oxide transformations in Sediments along a salinity gradient in the Weser Estuary.
Aquatic Microbial Ecology, 2009Co-Authors: Michael Nielsen, Dirk De Beer, Armin Gieseke, Niels Peter RevsbechAbstract:The dynamics of the nitrogen intermediates N 2 O and NO 2 - in estuarine Sediments were studied along a salinity gradient in the eutrophied Weser Estuary (Germany) using microsensors for N 2 O, NO 2 - , NO x - , and O 2 . During dark incubations in the laboratory of Sediment samples from a freshwater site, a brackish water site with fluctuating salinity, and a marine site, the effects of environmental changes in nitrogen availability and salinity on microscale Sediment dynamics were examined. Generally, Sediment levels of intermediates were low: 1 to 25 μM NO 2 - and 0 to 8 μM N 2 O. However, significant variation was found in accumulation patterns and in the potential of the residing microbial community to control Sediment releases of the intermediates. At fresh- and brackish water sites, NO 2 - production was found in the anOxic denitrification zone, and release from the Sediments was effectively prevented by activity of nitrite oxidisers in Oxic surface layers. In contrast, high rates of NO 2 - release occurred in marine Sediment, where NO 2 - production was predominantly associated with incomplete nitrification in Oxic layers. Similarly, stimulated partial nitrification due to NH 4 + addition led to NO 2 - liberation from brackish water Sediment. Production of N 2 O was never observed in Sediment from the brackish water site, which is naturally exposed to a daily regime of water column variations, but transient N 2 O accumulation was observed in the other Sediments. The production of N 2 O could be induced by an abrupt change in either NO 3 - or salinity, and was found in anOxic or micro-Oxic Sediment layers. Because Oxic Sediment layers showed little or no potential for N 2 O consumption (in contrast to NO 2 - ) the accumulation of N 2 O always resulted in release from the Sediment surface. Results demonstrate that changes in environmental parameters such as salinity and NO 3 - can trigger Sediment production and release of NO 2 - and N 2 O, but further suggest that microbial Sediment communities are highly adaptive and can become resistant towards intermediate release when regularly exposed to fluctuating conditions.
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Chimney construction by Chironomus riparius larvae in response to hypoxia: microbial implications for freshwater Sediments
Journal of The North American Benthological Society, 2005Co-Authors: Peter Stief, Larisa Nazarova, Dirk De BeerAbstract:AbstractMany shallow aquatic ecosystems with high nutrient loads experience periods of O2 depletion that evoke behavioral responses by macrobenthic organisms. The Sediment-dwelling midge larva Chironomus riparius reduces its deposit-feeding activity and allocates more time to burrow ventilation during periods of hypoxia. We investigated another striking behavioral adaptation of this species, i.e., the elongation of U-shaped Sediment burrows to chimneys that tower above the Sediment surface. Chironomus riparius larvae gradually abandoned burrow construction and took up chimney construction when exposed to hypOxic conditions in laboratory microcosms. Microsensors were used to show that the chimneys were Oxic Sediment compartments that were periodically irrigated by the larvae with oxygenated surface water. O2 uptake rates per unit interface area were significantly higher for chimneys than for the flat Sediment surface. This observation was consistent with the dense colonization of the chimneys by bacteria. ...
