Optical properties of dissolved organic matter relate to different dept-specific patterns of archaeal and bacterial community structure in the North Atlantic Ocean

ArticleProkaryotic abundance, activity and community composition were studied in the euphotic, intermediate and deep waters off the Galician coast (NW Iberian margin) in relation to the optical characterization of dissolved organic matter (DOM). Microbial (archaeal and bacterial) community structure was vertically stratified. Among the Archaea, Euryarchaeota, especially Thermoplasmata, was dominant in the intermediate waters and decreased with depth, whereas marine Thaumarchaeota, especially Marine Group I, was the most abundant archaeal phylum in the deeper layers. The bacterial community was dominated by Proteobacteria through the whole water column. However, Cyanobacteria and Bacteroidetes ocurrence was considerable in the upper layer and SAR202 was dominant in deep waters. Microbial composition and abundande were not shaped by the quantity of dissolved organic carbon, but instead they revealed a strong connection with the DOM quality. Archaeal communities were mainly related to the fluorescence of DOM (which indicates respiration of labile DOM and generation of refractory subproducts), while bacterial communities were mainly linked to the aromaticity/age of the DOM produced along the water column. Taken together, our results indicate that the microbial community composition is associated with the DOM composition of the water masses, suggesting that distinct microbial taxa have the potential to use and/or produce specific DOM compounds.Versión del edito

Sample dilution and bacterial community composition influence empirical leucine-to-carbon conversion factors in surface waters of the world's oceans

Research articleThe transformation of leucine incorporation into prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world’s oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e. removal of grazers; F treatment) or filtration combined with dilution (i.e. relieving also resource competition; FD treatment). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu-1 and were significantly lower in the filtered and diluted (FD) than in the filtered (F) treatments. Also, changes in bacterial community composition during the incubations, as assessed by Automated Ribosomal Intergenic Spacer Analysis (ARISA), were stronger in the FD than in the F treatments, as compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCFs determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyll a concentration, picocyanobacterial abundance (mostly Prochlorococcus) and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCFs variability in the F treatment, supporting the view that both Prochlorococcus and HNA prokaryotes incorporate leucine in substantial amounts although resulting into relatively low carbon production rates in the oligotrophic ocean.En prensa3,829

Biogeography of planktonic bacterial communities across the whole Mediterranean Sea

Bacterial population distribution in the Mediterranean Sea has been mainly studied by considering small geographical areas or specific phylogenetic groups. The present study is a molecular microbiology investigation aimed to identify the environmental factors driving total bacterioplankton community composition of seawater samples collected along a transect covering the whole Mediterranean Sea. We performed automated ribosomal intergenic sequence analysis (ARISA) and microscope evaluation of prokaryotic abundance of seawater sampled across both vertical profiles and longitudinal transects in the whole basin. Prokaryotic abundance decreased with depth at all the stations and presented similar values in epi-, meso- and bathypelagic layers across the whole Mediterranean Sea. However, peculiar bacterial assemblages were selected along a longitudinal transect in the epipelagic layers of the eastern and western sub-basins. Vertical differences of the bacterial communities were observed only when considering the epi- and bathypelagic waters, while the study of the structure of bacterial communities at a finer scale across the water column displayed higher variability at the intermediate layers. Nonetheless, different physico-chemical factors were significantly related to the distribution of bacterial populations, both according to geographic position and down the water column in the whole Mediterranean Sea. These results demonstrated that bacterial assemblages are putatively correlated to different water masses of the complex hydrographical systems of the eastern and western Mediterranean sub-basins

4to. Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad. Memoria académica

Este volumen acoge la memoria académica de la Cuarta edición del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad, CITIS 2017, desarrollado entre el 29 de noviembre y el 1 de diciembre de 2017 y organizado por la Universidad Politécnica Salesiana (UPS) en su sede de Guayaquil. El Congreso ofreció un espacio para la presentación, difusión e intercambio de importantes investigaciones nacionales e internacionales ante la comunidad universitaria que se dio cita en el encuentro. El uso de herramientas tecnológicas para la gestión de los trabajos de investigación como la plataforma Open Conference Systems y la web de presentación del Congreso http://citis.blog.ups.edu.ec/, hicieron de CITIS 2017 un verdadero referente entre los congresos que se desarrollaron en el país. La preocupación de nuestra Universidad, de presentar espacios que ayuden a generar nuevos y mejores cambios en la dimensión humana y social de nuestro entorno, hace que se persiga en cada edición del evento la presentación de trabajos con calidad creciente en cuanto a su producción científica. Quienes estuvimos al frente de la organización, dejamos plasmado en estas memorias académicas el intenso y prolífico trabajo de los días de realización del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad al alcance de todos y todas

Dominio Bacteria: Listado de géneros y especies de bacterias marinas en Galicia

Capítulo de libroEl conocimiento de la diversidad bacteriana en aguas marinas en Galicia es incipiente y se basa actualmente en el uso de técnicas de análisis molecular (secuenciación de un fragmento del gen ARNr 16S en aguas de ría, de plataforma, aguas oceánicas costeras, en playas y en sedimentos intermareales. La lista publicada incluye fundamentalmente géneros, debido a la imposibilidad de identificar con fiabilidad a nivel de especie basándose en esta técnica a partir de muestras oceánicasEn prens

Vertical stratificaction of bacterial communities driven by multiple environmental factors in the dark waters off the Galician coast (NW Spain)

scientific articleThe processesmediatedbymicrobialplanktoniccommunitiesoccuralongtheentirewatercolumn,yet the microbialactivityandcompositionhavebeenstudiedmainlyinsurfacewaters.Thisresearchex- amined theverticalvariationinbacterialabundance,activityandcommunitycompositionandstructure from surfacedownto5000mdepthfollowingalongitudinaltransectofftheGaliciancoast(NWIberian margin, from43°N, 9°W to43°N, 15°W). Communityactivityandcompositionchangedwithdepth.The leucine incorporationratesdecreasedfromtheeuphoticlayertothebathypelagicwatersbythreeorders of magnitude,whereasprokaryoticabundancedecreasedonlybyoneorderofmagnitude.Therelative abundance ofSAR11and Alteromonas, determined bycatalyzedreporteddeposition fluorescenceinsitu hybridization(CARD-FISH),decreasedwithdepth.Meanwhile,thecontributionofSAR202andSAR324 wassignificantly higherinthedeeperlayers(i.e.NEADW,NorthEastAtlanticDeepWaterandLDW, LowerDeepWater)thanintheeuphoticzone.Bacterialcommunitystructure,assessedbyAutomated Ribosomal IntergenicSpacerAnalysis(ARISA),wasdepth-specific. Adistancebasedlinearmodel (DistLM) revealedthatthevariabilityfoundinbacterialcommunitystructurewasmainlyexplainedby temperaturenitrate,phosphate,dissolvedorganicmatter(DOM) fluorescence, prokaryoticabundance, leucine incorporationandtoalesserextentsalinity,oxygen,CDOMabsorbanceanddissolvedorganic carbon concentration.Ourresultsdisplayedabacterialcommunitystructureshapednotonlybydepth- relatedphysicochemicalfeaturesbutalsobyDOMquality,indicatingthatdifferentprokaryotictaxahave the potentialtometabolizeparticularDOMsources.Postprint2,421

VERTICAL AND SEASONAL PATTERNS CONTROL BACTERIOPLANKTON COMMUNITIES AT TWO HORIZONTALLY COHERENT COASTAL UPWELLING SITES OFF GALICIA (NW SPAIN)

Analysis of seasonal patterns of marine bacterial community structure along horizontal and vertical spatial scales can help to predict long-term responses to climate change. Several recent studies have shown predictable seasonal reoccurrence of bacterial assemblages. However, only a few have assessed temporal variability over both horizontal and vertical spatial scales. Here we simultaneously studied the bacterial community structure at two different locations and depths in shelf waters of a coastal upwelling system during an annual cycle. The most noticeable biogeographic patterns observed were seasonality, horizontal homogeneity and spatial synchrony in bacterial diversity and community structure related with regional upwelling-downwelling dynamics. Water column mixing eventually disrupted bacterial community structure vertical heterogeneity. Our results are consistent with previous temporal studies of marine bacterioplankton in other temperate regions, and also suggest a marked influence of regional factors on the bacterial communities inhabiting this coastal upwelling system. Bacterial-mediated carbon fluxes in this productive region appear to be mainly controlled by community structure dynamics in surface waters, and local environmental factors at the base of the euphotic zone

Respiratory support in patients with severe COVID-19 in the International Severe Acute Respiratory and Emerging Infection (ISARIC) COVID-19 study: a prospective, multinational, observational study

Background: Up to 30% of hospitalised patients with COVID-19 require advanced respiratory support, including high-flow nasal cannulas (HFNC), non-invasive mechanical ventilation (NIV), or invasive mechanical ventilation (IMV). We aimed to describe the clinical characteristics, outcomes and risk factors for failing non-invasive respiratory support in patients treated with severe COVID-19 during the first two years of the pandemic in high-income countries (HICs) and low middle-income countries (LMICs). Methods: This is a multinational, multicentre, prospective cohort study embedded in the ISARIC-WHO COVID-19 Clinical Characterisation Protocol. Patients with laboratory-confirmed SARS-CoV-2 infection who required hospital admission were recruited prospectively. Patients treated with HFNC, NIV, or IMV within the first 24 h of hospital admission were included in this study. Descriptive statistics, random forest, and logistic regression analyses were used to describe clinical characteristics and compare clinical outcomes among patients treated with the different types of advanced respiratory support. Results: A total of 66,565 patients were included in this study. Overall, 82.6% of patients were treated in HIC, and 40.6% were admitted to the hospital during the first pandemic wave. During the first 24 h after hospital admission, patients in HICs were more frequently treated with HFNC (48.0%), followed by NIV (38.6%) and IMV (13.4%). In contrast, patients admitted in lower- and middle-income countries (LMICs) were less frequently treated with HFNC (16.1%) and the majority received IMV (59.1%). The failure rate of non-invasive respiratory support (i.e. HFNC or NIV) was 15.5%, of which 71.2% were from HIC and 28.8% from LMIC. The variables most strongly associated with non-invasive ventilation failure, defined as progression to IMV, were high leukocyte counts at hospital admission (OR [95%CI]; 5.86 [4.83-7.10]), treatment in an LMIC (OR [95%CI]; 2.04 [1.97-2.11]), and tachypnoea at hospital admission (OR [95%CI]; 1.16 [1.14-1.18]). Patients who failed HFNC/NIV had a higher 28-day fatality ratio (OR [95%CI]; 1.27 [1.25-1.30]). Conclusions: In the present international cohort, the most frequently used advanced respiratory support was the HFNC. However, IMV was used more often in LMIC. Higher leucocyte count, tachypnoea, and treatment in LMIC were risk factors for HFNC/NIV failure. HFNC/NIV failure was related to worse clinical outcomes, such as 28-day mortality. Trial registration This is a prospective observational study; therefore, no health care interventions were applied to participants, and trial registration is not applicable