Les arrels de certes plantes seleccionen els microorganismes que les colonitzen

Els aiguamolls són ambients de gran biodiversitat, vàlua ambiental i importància hídrica que juguen un paper rellevant en l'ecosistema. La vegetació d'aquests ambients són plantes aquàtiques a les arrels de les quals viuen microorganismes que, per exemple, poden regular el seu desenvolupament i modificar la circulació de nutrients en els sediments del voltant. Un estudi realitzat per investigadors de la UAB i de la Universitat de Girona en col·laboració amb la Estació Biològica de Doñana posa de manifest que les arrels de certes espècies tenen un efecte seleccionador sobre les comunitats de microorganismes.Wetlands are environments of high biodiversity, environmental value and water importance that play a relevant role in the ecosystem. The vegetation in these environments consists of aquatic plants in whose roots microorganisms live which, for example, can regulate their development and modify the circulation of nutrients in the surrounding sediments. A study conducted by researchers of the UAB and the University of Girona in cooperation with the Doñana Biological Station shows that the roots of certain species have a selecting effect on the communities of microorganisms.Los humedales son ambientes de gran biodiversidad, valía ambiental e importancia hídrica que juegan un papel relevante en el ecosistema. La vegetación de estos ambientes son plantas acuáticas en cuyas raíces viven microorganismos que, por ejemplo, pueden regular su desarrollo y modificar la circulación de nutrientes en los sedimentos de los alrededores. Un estudio realizado por investigadores de la UAB y de la Universitat de Girona en colaboración con la Estación Biológica de Doñana pone de manifiesto que las raíces de ciertas especies tienen un efecto seleccionador sobre las comunidades de microorganismos

Resolent els misteris de la Terra : els grans dipòsits sedimentaris de ferro tindrien el seu origen en el plàncton dels oceans primitius

La cubeta de Kabuno, al nord del llac Kivu, en ple centre d'Àfrica (República Democràtica del Congo), permet viatjar en el temps i fer una ullada a com eren els oceans primitius i com l'activitat d'uns microorganismes va generar, ara fa milions d'anys, els enormes dipòsits de ferro existents a la Terra. Gairebé un terç del bacterioplàncton d'aquesta cubeta lacustre oxida ferro utilitzant la llum en un tipus de fotosíntesi sense oxigen que es creu que era la predominant a la terra primitiva durant bilions d'anys.La cubeta de Kabuno, al norte del lago Kivu, en pleno centro de África (República Democrática del Congo), permite viajar en el tiempo y echar un vistazo a cómo eran los océanos primitivos y cómo la actividad de unos microorganismos generó, hace millones de años, los enormes depósitos de hierro existentes en la Tierra. Casi un tercio del bacterioplancton de esta cubeta lacustre oxida hierro utilizando la luz en un tipo de fotosíntesis sin oxígeno que se cree que era la predominante en la tierra primitiva durante billones de años.Kabuno bay, located in the north of Lake Kivu, in the heart of Africa (Democratic Republic of the Congo) offers a glimpse into the early oceans, showing how a tiny group of microbes developed the biggest iron deposits on Earth. Nearly one third of the microbes present in this freshwater basin grow by performing a different kind of photosynthesis by iron oxidation. It is believed that this kind of photosynthesis was the predominant on the early Earth over billions of years

Photoferrotrophy: Remains of an ancient photosynthesis in modern environments

© 2017 Camacho, Walter, Picazo and Zopfi. Photoferrotrophy, the process by which inorganic carbon is fixed into organic matter using light as an energy source and reduced iron [Fe(II)] as an electron donor, has been proposed as one of the oldest photoautotrophic metabolisms on Earth. Under the iron-rich (ferruginous) but sulfide poor conditions dominating the Archean ocean, this type of metabolism could have accounted for most of the primary production in the photic zone. Here we review the current knowledge of biogeochemical, microbial and phylogenetic aspects of photoferrotrophy, and evaluate the ecological significance of this process in ancient and modern environments. From the ferruginous conditions that prevailed during most of the Archean, the ancient ocean evolved toward euxinic (anoxic and sulfide rich) conditions and, finally, much after the advent of oxygenic photosynthesis, to a predominantly oxic environment. Under these new conditions photoferrotrophs lost importance as primary producers, and now photoferrotrophy remains as a vestige of a formerly relevant photosynthetic process. Apart from the geological record and other biogeochemical markers, modern environments resembling the redox conditions of these ancient oceans can offer insights into the past significance of photoferrotrophy and help to explain how this metabolism operated as an important source of organic carbon for the early biosphere. Iron-rich meromictic (permanently stratified) lakes can be considered as modern analogs of the ancient Archean ocean, as they present anoxic ferruginous water columns where light can still be available at the chemocline, thus offering suitable niches for photoferrotrophs. A few bacterial strains of purple bacteria as well as of green sulfur bacteria have been shown to possess photoferrotrophic capacities, and hence, could thrive in these modern Archean ocean analogs. Studies addressing the occurrence and the biogeochemical significance of photoferrotrophy in ferruginous environments have been conducted so far in lakes Matano, Pavin, La Cruz, and the Kabuno Bay of Lake Kivu. To date, only in the latter two lakes a biogeochemical role of photoferrotrophs has been confirmed. In this review we critically summarize the current knowledge on iron-driven photosynthesis, as a remains of ancient Earth biogeochemistry

Ancient Microbes from Halite Fluid Inclusions: Optimized Surface Sterilization and DNA Extraction

Fluid inclusions in evaporite minerals (halite, gypsum, etc.) potentially preserve genetic records of microbial diversity and changing environmental conditions of Earth's hydrosphere for nearly one billion years. Here we describe a robust protocol for surface sterilization and retrieval of DNA from fluid inclusions in halite that, unlike previously published methods, guarantees removal of potentially contaminating surface-bound DNA. The protocol involves microscopic visualization of cell structures, deliberate surface contamination followed by surface sterilization with acid and bleach washes, and DNA extraction using Amicon centrifugal filters. Methods were verified on halite crystals of four different ages from Saline Valley, California (modern, 36 ka, 64 ka, and 150 ka), with retrieval of algal and archaeal DNA, and characterization of the algal community using ITS1 sequences. The protocol we developed opens up new avenues for study of ancient microbial ecosystems in fluid inclusions, understanding microbial evolution across geological time, and investigating the antiquity of life on earth and other parts of the solar system

Geochemical Characterization of Two Ferruginous Meromictic Lakes in the Upper Midwest, USA

To elucidate the role of (bio)geochemical processes that fueled iron and carbon cycling in early Earth oceans, modern environments with similar geochemical conditions are needed. As the range of chemical, physical, and biological attributes of the Precambrian oceans must have varied in time and space, lakes of different compositions are useful to ask and answer different questions. Tropical Lake Matano (Indonesia), the largest known ferruginous lake, and Lake Pavin (France), a meromictic crater lake, are the two best studied Precambrian ocean analogs. Here we present seasonal geochemical data from two glacially formed temperate ferruginous lakes: Brownie Lake (MN) and Canyon Lake (MI) in the Upper Midwest, USA. The results of seasonal monitoring over multiple years indicate that (1) each lake is meromictic with a dense, anoxic monimolimnion, which is separated from the less dense, oxic mixolimnion by a sharp chemocline; (2) below this chemocline are ferruginous waters, with maximum dissolved iron concentrations \u3e1 mM; (3) meromixis in Brownie Lake is largely anthropogenic, whereas in Canyon Lake it is natural; (4) the shallow chemocline of Brownie Lake and high phosphorus reservoir make it an ideal analog to study anoxygenic photosynthesis, elemental ratios, and mineralogy; and (5) a deep penetrating suboxic zone in Canyon Lake may support future studies of suboxic microbial activity or mineral transformation

Les arrels de certes plantes seleccionen els microorganismes que les colonitzen

Els aiguamolls són ambients de gran biodiversitat, vàlua ambiental i importància hídrica que juguen un paper rellevant en l'ecosistema. La vegetació d'aquests ambients són plantes aquàtiques a les arrels de les quals viuen microorganismes que, per exemple, poden regular el seu desenvolupament i modificar la circulació de nutrients en els sediments del voltant. Un estudi realitzat per investigadors de la UAB i de la Universitat de Girona en col·laboració amb la Estació Biològica de Doñana posa de manifest que les arrels de certes espècies tenen un efecte seleccionador sobre les comunitats de microorganismes.Wetlands are environments of high biodiversity, environmental value and water importance that play a relevant role in the ecosystem. The vegetation in these environments consists of aquatic plants in whose roots microorganisms live which, for example, can regulate their development and modify the circulation of nutrients in the surrounding sediments. A study conducted by researchers of the UAB and the University of Girona in cooperation with the Doñana Biological Station shows that the roots of certain species have a selecting effect on the communities of microorganisms.Los humedales son ambientes de gran biodiversidad, valía ambiental e importancia hídrica que juegan un papel relevante en el ecosistema. La vegetación de estos ambientes son plantas acuáticas en cuyas raíces viven microorganismos que, por ejemplo, pueden regular su desarrollo y modificar la circulación de nutrientes en los sedimentos de los alrededores. Un estudio realizado por investigadores de la UAB y de la Universitat de Girona en colaboración con la Estación Biológica de Doñana pone de manifiesto que las raíces de ciertas especies tienen un efecto seleccionador sobre las comunidades de microorganismos

High archaeal richness in the water column of a freshwater sulfurous karstic lake along an interannual study.

12 páginas, 2 tablas, 5 figures.We surveyed the archaeal assemblage in a stratified sulfurous lake (Lake Vilar, Banyoles, Spain) over 5 consecutive years to detect potential seasonal and interannual trends in the free-living planktonic Archaea composition. The combination of different primer pairs and nested PCR steps revealed an unexpectedly rich archaeal community. Overall, 140 samples were analyzed, yielding 169 different 16S rRNA gene sequences spread over 14 Crenarchaeota (109 sequences) and six Euryarchaeota phylogenetic clusters. Most of the Crenarchaeota (98% of the total crenarchaeotal sequences) affiliated within the Miscellaneous Crenarchaeota Group (MCG) and were related to both marine and freshwater phylotypes. Euryarchaeota mainly grouped within the Deep Hydrothermal Vent Euryarchaeota (DHVE) cluster (80% of the euryarchaeotal sequences) and the remaining 20% distributed into three less abundant taxa, most of them composed of soil and sediment clones. The largest fraction of phylotypes from the two archaeal kingdoms (79% of the Crenarchaeota and 54% of the Euryarchaeota) was retrieved from the anoxic hypolimnion, indicating that these cold and sulfide-rich waters constitute an unexplored source of archaeal richness. The taxon rank-frequency distribution showed two abundant taxa (MCG and DHVE) that persisted in the water column through seasons, plus several rare ones that were only detected occasionally. Differences in richness distribution and seasonality were observed, but no clear correlations were obtained when multivariate statistical analyses were carried out.This study was funded through projects VIARC (Ref. REN 2003-08333-GLO) and CRENYC (Ref. CGL2006-12058-BOS) to C.M.B. and E.O.C. from the Spanish Ministerio de Educación y Ciencia (MEC). M.L. is recipient of a PhD student fellowship (BES-2004-5127) from the Spanish MEC.Peer reviewe

Diversity, dynamics and activity of mesophilic Archaea in stratified feshwater lakes. Implications in biogeochemical cycles

Aquesta tesi doctoral va estudiar la diversitat (riquesa i abundància), la distribució i la dinàmica de les comunitats planctòniques d'Archaea presents a diferents llacs estratificats temperats d'aigua dolça per aportar evidencies sobre la seva distribució i la seva possible activitat en aquests ecosistemes en relació als cicles biogeoquímics presents en els mateixos. Es varen estudiar dos estanyols d'origen càrstic (l'Estanyol del Vilar durant cinc anys consecutius (2001-2005) i l'Estanyol de Can Coromina) i un llac d'origen volcànic (Llac Kivu) analitzant, per una banda, la seva comunitat planctònica d'Archaea mitjançant una aproximació molecular i, per una altra, la seva possible activitat en aquests ambients (p.e., la nitrificació i la fixació de carboni). Per contextualitzar els resultats, es va realitzar un anàlisi in silico dels patrons de distribució global dels Archaea mesòfils mitjançant un anàlisi a nivell de llinatge combinant seqüències del gen 16S rRNA amb diferents eines estadístiques i d'ecologia general.The present PhD thesis analysed the diversity (richness and evenness), distribution and dynamics of planktonic Archaea in several temperate stratified freshwater lakes to shed some light on their distribution and potential activity in these ecosystems in relation to prevalent biogeochemical cycles. In this sense, two karstic lagoons (Lake Vilar during five consecutive years (2001-2005) and Coromina lagoon) and a volcanic lake (Lake Kivu) were studied analysing, in the one hand, their archaeal planktonic community throughout a molecular approach and, in the other hand, their potential acitivity in these environments (e.g., nitrification and carbon fixation). In order to contextualize the obtained results, an in silico phylogenetic lineage-based analysis on the global distribution of lacustrine Archaea was conducted using 16S rRNA gene sequences in combination with statistical and general ecology tools