Variabilidad de vibrios planctónicos y epifíticos en un ambiente costero afectado por proliferaciones de Ostreopsis

Vibrios include several pathogenic bacteria that occur in aquatic environments. The presence of Vibrio has been assessed in many ecosystems by culture-based techniques. However, little is known on the contribution of Vibrios in the sea, especially in areas subject to harmful algal blooms. A preliminary study in Sant Andreu de Llavaneres beach (NW Mediterranean) showed the presence of some Vibrio species during a recurrent bloom of the harmful benthic dinoflagellate Ostreopsis cf. ovata. In order to establish the importance of Vibrios in a coastal area of the NW Mediterranean and to study the association with the dinoflagellate, we conducted a sampling monitoring for one year to quantify the concentration of Vibrios both in the water (free-living and attached to particles) and in the epiphytic community of macroalgae. The aims were 1) to evaluate the relative abundance of Vibrio in the epiphytic and in the planktonic bacterial community, 2) to assess the percentage of free-living and attached Vibrios in the planktonic community, and 3) to determine whether the presence of Vibrios is associated with the blooms of the toxic dinoflagellate Ostreopsis or with other environmental parameters. For this purpose, a CARD-FISH molecular probe was applied for the specific detection of bacteria belonging to the genus Vibrio. Cells were quantified and the abundance of both particles and bacteria attached to particles were assessed. The maximum Vibrio concentration (1.3x104 cells ml–1 and 1.4x106 cells g–1 FW, for planktonic and epiphytic samples, respectively) was detected in September. Free-living Vibrios contributed 0.38±0.24% to the total free-living planktonic community and 1.12±0.28% to the epiphytic bacterial community. However, their contribution was particularly high in the planktonic community attached to particles (17.37±20.49%). Although in the planktonic community Vibrio was found preferentially free-living (82.63±20.01%), particles are a niche for Vibrios, since in particles Vibrios may represent up to 72% of the total attached bacterial community. Abundance of planktonic Vibrio was correlated with Ostreopsis concentration and it is likely that they play a role in the wound infections suffered by beach users during the bloom.El género Vibrio incluye a varias bacterias patogénicas que se encuentran en ecosistemas acuáticos. La presencia de Vibrio se ha estimado en muchos ecosistemas mediante técnicas basadas en cultivos. Sin embargo, se conoce poco sobre la contribución de Vibrios en el mar, especialmente en áreas afectadas por proliferaciones algales nocivas. Un estudio preliminar en la playa de Sant Andreu de Llavaneres (Mediterráneo NO) mostró la presencia de algunas especies de Vibrio durante una proliferación recurrente del dinoflagelado béntico nocivo Ostreopsis cf. ovata. Para poder establecer la relevancia de los Vibrios en un área costera del Mediterráneo NO y estudiar su asociación con el dinoflagelado, realizamos un muestreo de monitoreo durante un año para cuantificar la concentración de Vibrios tanto en el agua (de vida libre y adheridos a partículas) y en la comunidad epifítica de macroalgas con los objetivos de 1) evaluar la abundancia relativa de Vibrio en la comunidad bacteriana tanto planctónica como epifítica, 2) estimar el porcentaje de Vibrios de vida libre y adheridos a partículas en la comunidad bacteriana planctónica y 3) determinar si la presencia de Vibrios está relacionada con las proliferaciones del dinoflagelado Ostreopsis o con otros parámetros ambientales. Para este propósito, se aplicó una sonda molecular de CARD-FISH para la detección específica de bacterias pertenecientes al género Vibrio. Se cuantificaron las células y también la abundancia de partículas y de las bacterias adheridas a estas partículas. La máxima concentración de Vibrio (1.3x104 cels ml–1 y 1.4x106 cels g–1 PF, para muestras planctónicas y epifíticas, respectivamente) fue detectada en Septiembre. Los Vibrios de vida libre contribuyeron un 0.38±0.24% al total de la comunidad bacteriana de vida libre y un 1.12±0.28% a la comunidad bacteriana epifítica. Sin embargo, su contribución fue especialmente elevada en la comunidad bacteriana adherida a partículas (17.37±20.49%). Aunque en la comunidad planctónica Vibrio se encontraba preferentemente no adheridos a partículas (82.63±20.01%), las partículas constituyen un nicho para Vibrios, ya que pueden llegar a representar hasta un 72% de la comunidad bacteriana adherida a partículas. La abundancia de Vibrio en el plancton se correlacionó con la concentración de Ostreopsis, y es posible que éstos jueguen un papel en las infecciones de heridas que sufren los bañistas durante las proliferaciones algales

Prokaryotic capability to use organic substrates across the global tropical and subtropical ocean

Prokaryotes play a fundamental role in decomposing organic matter in the ocean, but little is known about how microbial metabolic capabilities vary at the global ocean scale and what are the drivers causing this variation. We aimed at obtaining the first global exploration of the functional capabilities of prokaryotes in the ocean, with emphasis on the under-sampled meso- and bathypelagic layers. We explored the potential utilization of 95 carbon sources with Biolog GN2 plates® in 441 prokaryotic communities sampled from surface to bathypelagic waters (down to 4,000 m) at 111 stations distributed across the tropical and subtropical Atlantic, Indian, and Pacific oceans. The resulting metabolic profiles were compared with biological and physico-chemical properties such as fluorescent dissolved organic matter (DOM) or temperature. The relative use of the individual substrates was remarkably consistent across oceanic regions and layers, and only the Equatorial Pacific Ocean showed a different metabolic structure. When grouping substrates by categories, we observed some vertical variations, such as an increased relative utilization of polymers in bathypelagic layers or a higher relative use of P-compounds or amino acids in the surface ocean. The increased relative use of polymers with depth, together with the increases in humic DOM, suggest that deep ocean communities have the capability to process complex DOM. Overall, the main identified driver of the metabolic structure of ocean prokaryotic communities was temperature. Our results represent the first global depiction of the potential use of a variety of carbon sources by prokaryotic communities across the tropical and the subtropical ocean and show that acetic acid clearly emerges as one of the most widely potentially used carbon sources in the ocean

Eutrophication and acidification: Do they induce changes in the dissolvedorganic matter dynamics in the coastal Mediterranean Sea?

Original research paperTwo mesocosms experiments were conducted in winter 2010 and summer 2011 to examine how increased pCO2and/or nutrient concentrations potentially perturbate dissolved organic matter dynamics in natural microbialassemblages. Thefluorescence signals of protein- and humic-like compounds were used as a proxy for labileand non-labile material, respectively, while the evolution of bacterial populations, chlorophylla(Chla) anddissolved organic carbon (DOC) concentrations were used as a proxy for biological activity. For both seasons,the presence of elevated pCO2did not cause any significant change in the DOC dynamics (p-valueb0.05). Theconditions that showed the greatest changes in prokaryote abundances and Chlacontent were those amendedwith nutrients, regardless of the change in pH. The temporal evolution offluorophores and optical indices re-vealed that the degree of humification of the organic molecules and their molecular weight changed significantlyin the nutrient-amended treatment. The generation of protein-like compounds was paired to increases in theprokaryote abundance, being higher in the nutrient-amended tanks than in the control. Different patterns inthe magnitude and direction of the generation of humic-like molecules suggested that these changes dependedon initial microbial populations and the availability of extra nutrient inputs. Based on our results, it is expected that in the future projected coastal scenarios the eutrophication processes will favor the transformations of labile and recalcitrant carbon regardless of changes in pCO2.MINECO, European Union, Generalitat de Catalunya, CSICVersión del editor3,25

Spatial variability of marine bacterial and archaeal communities along the particulate matter continuum.

International audienc

Abundance table for bathypelagic prokaryotes from Malaspina 2010 Expedition

Abundance table containing the number of reads for the Operational Taxonomic Units (OTUs) of particle-attached (PA) and free-living (FL) prokaryotes detected in 30 globally distributed stations from the Malaspina 2010 Expedition. Corresponds to 16SrDNA amplicons Illumina-based sequencing. Table is rarefied to 10,617 reads/sample. Columns are the samples; Rows are the OTUs. Taxonomy is attached after the last sample

Data from: Particle-association lifestyle is a phylogenetically conserved trait in bathypelagic prokaryotes

The free-living (FL) and particle-attached (PA) marine microbial communities have repeatedly been proved to differ in their diversity and composition in the photic ocean and also recently in the bathypelagic ocean at a global scale. However, although high taxonomic ranks have been proved to exhibit preferences for a PA or FL mode of life, it remains poorly understood whether two clear lifestyles do exist and how these are distributed across the prokaryotic phylogeny. We studied the FL and PA prokaryotes in 30 stations distributed worldwide within the bathypelagic oceanic realm using high throughput sequencing of their 16S rDNA. A high proportion of the bathypelagic prokaryotes were mostly found either attached to particles or freely in the surrounding water but rarely in both types of environments. In particular, this trait was deeply conserved through their phylogeny suggesting that the deep-ocean particles and the surrounding water constitute two highly distinct niches and that transitions from one to the other have been rare at an evolutionary time-scale. As a consequence, PA and FL communities had clear alpha- and beta-diversity differences that exceeded the global-scale geographical variation. Our study organizes the bathypelagic prokaryotic diversity into a reasonable number of ecologically coherent taxa regarding their association to particles, a first step for understanding which are the microbes responsible for the processing of the dissolved and particulate pools of organic matter that have a very different biogeochemical role in the deep ocean. -

Alignment used for phylogeny construction

Alignment used for the phylogenetic reconstruction

Phylogeny of the OTUs representative sequences

Phylogeny reconstruction of the OTUs. Newick format. Constructed with RAxML by the evolutionary placement of short sequences within an initial phylogeny of close full length sequences from SILVA database (See details in M&M)

Auxiliary data for the samples

Auxiliary data containing information on the station, size-fraction, date of sampling, ocean, depth and coordinates