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Valeria Souza - One of the best experts on this subject based on the ideXlab platform.
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Enrichment experiment changes microbial interactions in an ultra-Oligotrophic Environment
Frontiers in microbiology, 2015Co-Authors: Gabriel Yaxal Ponce-soto, Eneas Aguirre-von-wobeser, Luis E. Eguiarte, James J. Elser, Zarraz M.p. Lee, Valeria SouzaAbstract:The increase of nutrients in water bodies, in particular nitrogen (N) and phosphorus (P) due to the recent expansion of agricultural and other human activities is accelerating Environmental degradation of these water bodies, elevating the risk of eutrophication and reducing biodiversity. To evaluate the ecological effects of the influx of nutrients in an Oligotrophic and stoichiometrically imbalanced Environment, we performed a replicated in situ mesocosm experiment. We analyzed the effects of a N- and P-enrichment on the bacterial interspecific interactions in an experiment conducted in the Cuatro Cienegas Basin (CCB) in Mexico. This is a desert ecosystem comprised of several aquatic systems with a large number of microbial endemic species. The abundance of key nutrients in this basin exhibits strong stoichiometric imbalance (high N:P ratios), suggesting that species diversity is maintained mostly by competition for resources. We focused on the biofilm formation and antibiotic resistance of 960 strains of cultivated bacteria in two habitats, water and sediment, before and after three weeks of fertilization. The water habitat was dominated by Pseudomonas, while Halomonas dominated the sediment. Strong antibiotic resistance was found among the isolates at time zero in the nutrient-poor bacterial communities, but resistance declined in the bacteria isolated in the nutrient-rich Environments, suggesting that in the nutrient-poor original Environment, negative inter-specific interactions were important, while in the nutrient-rich Environments, competitive interactions are not so important. In water, a significant increase in the percentage of biofilm-forming strains was observed for all treatments involving nutrient addition.
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Two-role model of an interaction network of free-living γ-proteobacteria from an Oligotrophic Environment.
Environmental microbiology, 2013Co-Authors: Eneas Aguirre-von-wobeser, Gabriel Yaxal Ponce-soto, Luis E. Eguiarte, Gloria Soberón-chávez, Mirna Vázquez-rosas-landa, Valeria SouzaAbstract:Antagonistic interactions are frequently observed among bacteria in the Environment and result in complex networks, which could promote co‐existence, and therefore promote biodiversity. We analysed interactions of aquatic bacteria isolated by their ability to grow in Pseudomonas isolation agar from Churince, Cuatro Cienegas, Mexico. In the resulting network, highly antagonistic and highly sensitive strains could be distinguished, forming a largely hierarchical structure. Most of the highly antagonistic strains belonged to the genus Pseudomonas. The network was sender‐determined, which means that the antagonist strains had a larger influence on its structure than the sensitive ones. Very few interactions were necessary to connect all strains, implying that the network was ‘small world’. The network was highly nested, having a core of highly interacting strains, with which the less antagonistic or highly sensitive interact. A probabilistic model was built, which captured most features of the network. Biological interpretation of the model implied a state in which many different antagonistic mechanisms were present, and most strains were resistant to them. Our work shows that strains of Pseudomonas from the water column at Cuatro Cienegas have the potential to interact antagonistically with many closely related strains and that these interactions are usually not reciprocal.
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Genomics of Bacteria from an Ancient Marine Origin: Clues to Survival in an Oligotrophic Environment
Earth and Environmental Sciences, 2011Co-Authors: Luis David Alcaraz, Valeria Souza, Varinia López-ramírez, Alejandra Moreno-letelier, Luis Herrera-estrella, Gabriela Olmedo-ÁlvarezAbstract:Luis David Alcaraz1, Varinia Lopez-Ramirez2, Alejandra Moreno-Letelier3, Luis Herrera-Estrella4, Valeria Souza5 and Gabriela Olmedo-Alvarez2 1Department of Genomics and Health, Center for Advanced Research in Public Health, Valencia, 2Departamento de Ingenieria Genetica, Cinvestav Unidad Irapuato, 3Division of Biology, Imperial College London, Silwood Park Campus, Ascot, 4Langebio, Cinvestav, Mexico 5Departamento de Ecologia Evolutiva, Instituto de Ecologia, Universidad Nacional Autonoma de Mexico 1Spain 2,4.5Mexico 3UK
Ruben Sommaruga - One of the best experts on this subject based on the ideXlab platform.
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Bacterial Communities Associated With Spherical Nostoc Macrocolonies.
Frontiers in Microbiology, 2019Co-Authors: Pablo Aguilar, Cristina Dorador, Irma Vila, Ruben SommarugaAbstract:Species of the genus Nostoc (Cyanobacteria) can form large colonies of up to several centimetres in diameter that may represent a unique habitat for bacteria in freshwaters. Bacteria inside the colony are segregated from the surrounding water and largely dependent on the metabolism of this primary producer. However, the existence of a specific bacterial community associated with free-living representatives of Nostoc from lakes and streams is unknown. Here, we studied large Nostoc spp. colonies (ca. 2-10 cm in diameter) from two adjacent, high altitude aquatic Environments and assessed the diversity and community composition of the bacterial community associated with the inner gelatinous matrix. Further, we compared this community with that of the lake’s littoral zone where the colonies live or with the outer layer of the colony in samples collected from a stream. Alpha bacterial diversity in the inner gelatinous matrix of the colonies from both sites was lower than in the littoral zone or than in the outer layer. Significant differences in community composition were found between the inner and the outer layer, as well as between the inner gelatinous matrix and the littoral zone. Further, these differences were supported by the putative metabolic processes of the bacterial communities. Our results indicate the existence of a specific bacterial community inside macrocolonies of Nostoc spp. and also imply that the inner Environment exerts a strong selection. Finally, these large colonies represent not only a unique habitat, but probably also a hotspot of bacterial activity in an otherwise Oligotrophic Environment.
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Bacterial Communities Associated With Spherical Nostoc Macrocolonies
Frontiers Media S.A., 2019Co-Authors: Pablo Aguilar, Cristina Dorador, Irma Vila, Ruben SommarugaAbstract:Species of the genus Nostoc (Cyanobacteria) can form large colonies of up to several centimeters in diameter that may represent a unique habitat for bacteria in freshwaters. Bacteria inside the colony are probably segregated from the surrounding water and largely dependent on the metabolism of this primary producer. However, the existence of a specific bacterial community associated with free-living representatives of Nostoc from lakes and streams is unknown. Here, we studied large Nostoc spp. colonies (ca. 2–10 cm in diameter) from two adjacent, high altitude aquatic Environments and assessed the diversity, and community composition of the bacterial community associated with the inner gelatinous matrix (GM). Further, we compared this community with that of the lake’s littoral zone where the colonies live or with the outer layer (OL) of the colony in samples collected from a stream. Alpha bacterial diversity in the inner GM of the colonies from both sites was lower than in the littoral zone or than in the OL. Significant differences in community composition were found between the inner and the OL, as well as between the inner GM, and the littoral zone. Further, these differences were supported by the putative metabolic processes of the bacterial communities. Our results indicate the existence of a specific bacterial community inside macrocolonies of Nostoc spp. and also imply that the inner Environment exerts a strong selection. Finally, these large colonies represent not only a unique habitat, but probably also a hotspot of bacterial activity in an otherwise Oligotrophic Environment
Pablo Aguilar - One of the best experts on this subject based on the ideXlab platform.
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Bacterial Communities Associated With Spherical Nostoc Macrocolonies.
Frontiers in Microbiology, 2019Co-Authors: Pablo Aguilar, Cristina Dorador, Irma Vila, Ruben SommarugaAbstract:Species of the genus Nostoc (Cyanobacteria) can form large colonies of up to several centimetres in diameter that may represent a unique habitat for bacteria in freshwaters. Bacteria inside the colony are segregated from the surrounding water and largely dependent on the metabolism of this primary producer. However, the existence of a specific bacterial community associated with free-living representatives of Nostoc from lakes and streams is unknown. Here, we studied large Nostoc spp. colonies (ca. 2-10 cm in diameter) from two adjacent, high altitude aquatic Environments and assessed the diversity and community composition of the bacterial community associated with the inner gelatinous matrix. Further, we compared this community with that of the lake’s littoral zone where the colonies live or with the outer layer of the colony in samples collected from a stream. Alpha bacterial diversity in the inner gelatinous matrix of the colonies from both sites was lower than in the littoral zone or than in the outer layer. Significant differences in community composition were found between the inner and the outer layer, as well as between the inner gelatinous matrix and the littoral zone. Further, these differences were supported by the putative metabolic processes of the bacterial communities. Our results indicate the existence of a specific bacterial community inside macrocolonies of Nostoc spp. and also imply that the inner Environment exerts a strong selection. Finally, these large colonies represent not only a unique habitat, but probably also a hotspot of bacterial activity in an otherwise Oligotrophic Environment.
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Bacterial Communities Associated With Spherical Nostoc Macrocolonies
Frontiers Media S.A., 2019Co-Authors: Pablo Aguilar, Cristina Dorador, Irma Vila, Ruben SommarugaAbstract:Species of the genus Nostoc (Cyanobacteria) can form large colonies of up to several centimeters in diameter that may represent a unique habitat for bacteria in freshwaters. Bacteria inside the colony are probably segregated from the surrounding water and largely dependent on the metabolism of this primary producer. However, the existence of a specific bacterial community associated with free-living representatives of Nostoc from lakes and streams is unknown. Here, we studied large Nostoc spp. colonies (ca. 2–10 cm in diameter) from two adjacent, high altitude aquatic Environments and assessed the diversity, and community composition of the bacterial community associated with the inner gelatinous matrix (GM). Further, we compared this community with that of the lake’s littoral zone where the colonies live or with the outer layer (OL) of the colony in samples collected from a stream. Alpha bacterial diversity in the inner GM of the colonies from both sites was lower than in the littoral zone or than in the OL. Significant differences in community composition were found between the inner and the OL, as well as between the inner GM, and the littoral zone. Further, these differences were supported by the putative metabolic processes of the bacterial communities. Our results indicate the existence of a specific bacterial community inside macrocolonies of Nostoc spp. and also imply that the inner Environment exerts a strong selection. Finally, these large colonies represent not only a unique habitat, but probably also a hotspot of bacterial activity in an otherwise Oligotrophic Environment
Michel Leveau - One of the best experts on this subject based on the ideXlab platform.
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Transfers between a eutrophic ecosystem, the river Rhône, and an Oligotrophic ecosystem, the north-western Mediterranean Sea
Hydrobiologia, 1990Co-Authors: François Lochet, Michel LeveauAbstract:Transfer processes from a eutrophic ecosystem, the river Rhone, to an Oligotrophic Environment, the north-west Mediterranean Sea, were studied during the winter period, when inputs of dissolved and particulate matter are at their highest.
Michel Fontugne - One of the best experts on this subject based on the ideXlab platform.
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abrupt climate change sea surface salinity and paleoproductivity in the western mediterranean sea gulf of lion during the last 28 kyr
Palaeogeography Palaeoclimatology Palaeoecology, 2009Co-Authors: T Melki, Nejib Kallel, Frans Jorissen, F Guichard, Bernard Dennielou, Serge Berne, Laurent Labeyrie, Michel FontugneAbstract:Abstract The planktonic foraminiferal record of core MD99-2346 (Gulf of Lion) shows a decrease of sea surface temperature (SST) at the time of Heinrich event H2 (24–23.5 cal kyr BP), Younger Dryas and during the early to middle Holocene. These events were associated with a decrease of surface water salinity. The salinity lowering events were similar and synchronous to those recorded in the North Atlantic Ocean during H1, H2 and the Younger Dryas. They can be explained by a decrease in the salinity of the Atlantic surface water entering the Mediterranean through the Strait of Gibraltar. This result indicates that the Mediterranean Sea remained a concentration basin and that its freshwater budget was not significantly different from the modern conditions at the time of these low salinity events. Higher abundances of the benthic foraminifer Cibicidoides pachydermus at the time of Heinrich events (H2 and H1) may result from a seasonal, and more pulsed supply of labile organic matter. A high abundance of intermediate and deep infaunal taxa (Globobulimina spp.) during the warm Bolling/Allerod period is interpreted as a result of an increased lateral advection of organic matter to the deeper Environments of the Gulf of Lion. Surface water productivity, as reflected by the organic flux to the benthic ecosystem, reaches a maximum during the cold Younger Dryas period. It is possible that cold conditions at the time of the Younger Dryas have allowed an enhanced vertical mixing and deep-water cascading in the Gulf of Lion. This may have resulted in an increase of primary and export production. This putative intensification of deep-water cascading would have occurred after the sustained rise of the global sea-level from 16 to 12.5 cal kyr BP. The deglacial sea-level rise may also have played an important role in favouring the downslope movement of dense shelf water enriched in organic matter originating from the early Rhone delta complex. The conditions during the Holocene were characterized by a low surface productivity and Oligotrophic Environment similar to the modern situation.
