Suchergebnisse

14 pages, 9 figures, 2 tables ; We studied the seasonal variation of biotic and abiotic processes and the physico-chemical forcing factors involved in the production and consumption of dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) at a coastal sampling station in the northwestern Mediterranean. Monthly samplings of surface seawater for an 18-month period revealed that algal-associated DMSP and dimethylsulfoxide (DMSO) did not follow total phytoplankton biomass (measured as chlorophyll a [Chl a]). DMSP concentrations peaked 1 or 2 months later than the late winter Chl a bloom, following phytoplankton succession, whereas particulate DMSO was maximal in summer. Both Chl a–normalized concentrations (DMSP : Chl a and DMSO: Chl a) exhibited a clear seasonality with maxima in summer, which was indicative of concurrent phytoplankton succession and physiological acclimation toward higher dimethylated sulfur–producing taxa in summer. DMS concentrations also showed clear maxima in mid-summer and minima in winter, which is anticorrelated with Chl a. Gross DMS production rates were higher in summer, coinciding with higher DMSP-to-DMS conversion yields and exceeded microbial DMS consumption in this season. Heterotrophic bacteria and DMSP-assimilating phytoplankton only accounted for a portion (annual average 52%) of total DMSP transformations, suggesting that phytoplankton DMSP-lyases, either in stressed cells or upon grazing by herbivores, must play a more important role in DMS production than is generally believed. Calculated photolysis and measured microbial consumption alternated in dominance as DMS sinks over the year, with ventilation to the atmosphere generally being a minor loss process. Under higher solar radiation (from March to September), calculated photolysis followed variations of colored dissolved organic matter, a known DMS photosensitizer. ; This work was supported by the Spanish Ministry of Education and Science through a PhD studentship to M.V.-C., and through the projects MicroDiFF and MODIVUS (contracts REN2001-2120/MAR and CTM2005-04795/MAR to J.M.Gasol), by the Catalan government through grant 2005SGR00021 (to R.S.), and by the EU's 5th Framework Program through project BASICS (contract EVK3-CT-2002-00078 to J.M.G.). Additional support for R.P.K. was provided by a grant from the US National Science Foundation (OPP-0083078). This is a contribution to the objectives of the international program SOLAS and the Network of Excellence EUR-OCEANS of the EU's 6th Framework Program. ; Peer reviewed

Dissolved black carbon (DBC) plays a role in the oceanic carbon cycle. DBC originates from the heating and incomplete combustion of organic matter, including fossil fuels, a shared origin with polycyclic aromatic hydrocarbons (PAH). DBC is quantified using the benzene polycarboxylic acids produced by oxidation of the organic extract, a fraction of which derive from PAHs and other semivolatile aromatic-like compounds (SALCs). However, the current view of the DBC cycle does not take into account the inputs and sinks known for PAHs, such as diffusive air–water exchange and degradation. A meta-analysis of oceanic PAHs, SALCs, and DBC concentrations shows that SALCs account for 16% of DBC (ranging from 5% to 31%). Such a large contribution of semivolatile aromatic hydrocarbons to DBC is consistent with the large atmospheric input of SALCs (estimated as 400 Tg C y–1). Furthermore, photodegradation at the surface ocean and microbial degradation in the water column of semivolatile DBC can be important sinks, consistent with the ubiquitous occurrence of the degradation genes of the metabolic routes for aromatic hydrocarbons. Future work should focus on the characterization of semivolatile DBC and its degradation in order to constrain its contribution to refractory organic matter and the anthropogenic perturbation of the carbon cycle. ; This work was supported by the ANTOM project funded by the Spanish Research Agency from the Ministry of Science (PGC2018-096612-B-I00). N.T. and G.C. acknowledge FPI Ph.D. fellowships from the Spanish Research Agency. The research group of Global Change and Genomic Biogeochemistry receives support from the Catalan Government (2017SGR800). This research is part of POLARCSIC activities. IDAEA-CSIC is a Centre of Excellence Severo Ochoa (Spanish Ministry of Science and Innovation, Project CEX2018-000794-S). ; Peer reviewed

Scavenging of gas- and aerosol-phase organic pollutants by rain is an efficient wet deposition mechanism of organic pollutants. However, whereas snow has been identified as a key amplification mechanism of fugacities in cold environments, rain has received less attention in terms of amplification of organic pollutants. In this work, we provide new measurements of concentrations of perfluoroalkyl substances (PFAS), organophosphate esters (OPEs), and polycyclic aromatic hydrocarbons (PAHs) in rain from Antarctica, showing high scavenging ratios. Furthermore, a meta-analysis of previously published concentrations in air and rain was performed, with 46 works covering different climatic regions and a wide range of chemical classes, including PFAS, OPEs, PAHs, polychlorinated biphenyls and organochlorine compounds, polybromodiphenyl ethers, and dioxins. The rain–aerosol (KRP) and rain–gas (KRG) partition constants averaged 105.5 and 104.1, respectively, but showed large variability. The high field-derived values of KRG are consistent with adsorption onto the raindrops as a scavenging mechanism, in addition to gas–water absorption. The amplification of fugacities by rain deposition was up to 3 orders of magnitude for all chemical classes and was comparable to that due to snow. The amplification of concentrations and fugacities by rain underscores its relevance, explaining the occurrence of organic pollutants in environments across different climatic regions. ; We thank the staff of the Marine Technology Unit (UTM-CSIC) for their logistical support during the sampling campaign at Livingston Island, M. Pizarro for technical assistance, and The State Meteorological Agency (AEMET) for the meteorological assistance. This work was supported by Spanish Ministry of science to G.C. and A.M.-V. through predoctoral fellowships and projects SENTINEL (CTM2015-70535-P) and ANTOM (PGC2018-096612-B-l00). This research is part of POLARCSIC activities. The research group of Global Change and Genomic Biogeochemistry receives support from the Catalan Government (2017SGR800). Special thanks to TERNUA for sponsoring technical eco-friendly clothing and gear equipment for Antarctic campaigns. ; Peer reviewed

The composition of bacteria inhabiting the sea-surface microlayer (SML) is poorly characterized globally and yet undescribed for the Southern Ocean, despite their relevance for the biogeochemistry of the surface ocean. We report the abundances and diversity of bacteria inhabiting the SML and the subsurface waters (SSL) determined from a unique sample set from a polar coastal ecosystem (Livingston Island, Antarctica). From early to late austral summer (January–March 2018), we consistently found a higher abundance of bacteria in the SML than in the SSL. The SML was enriched in some Gammaproteobacteria genus such as Pseudoalteromonas, Pseudomonas, and Colwellia, known to degrade a wide range of semivolatile, hydrophobic, and surfactant-like organic pollutants. Hydrocarbons and other synthetic chemicals including surfactants, such as perfluoroalkyl substances (PFAS), reach remote marine environments by atmospheric transport and deposition and by oceanic currents, and are known to accumulate in the SML. Relative abundances of specific SML-enriched bacterial groups were significantly correlated to concentrations of PFASs, taken as a proxy of hydrophobic anthropogenic pollutants present in the SML and its stability. Our observations provide evidence for an important pollutant-bacteria interaction in the marine SML. Given that pollutant emissions have increased during the Anthropocene, our results point to the need to assess chemical pollution as a factor modulating marine microbiomes in the contemporaneous and future oceans. ; This work was supported by the Spanish Ministry of Science to GC and AM-V through predoctoral fellowships, and through projects SENTINEL (CTM2015-70535-P) and ISOMICS (CTM2015-65691-R). This research was part of POLARCSIC activities. The research group of Global Change and Genomic Biogeochemistry receives support from the Catalan Government (2017SGR800). ; Peer reviewed

7 páginas, 7 figuras ; To date different electrode materials have been used to improve the performance and reduce the costs of microbial fuel cells (MFCs). Particularly, there is a need to avoid the use of expensive Pt-based cathode materials. Here, we explored the use of vertically aligned carbon nanotubes (CNTs) deposited by plasma-enhanced chemical vapor deposition as cathode material in single chamber MFCs. In order to improve cell performance and lower the oxygen reduction reaction resistance at the cathode side, MnO2 catalyst was electrochemically deposited on the CNTs. Results show an increase in the output voltage and power density by two orders of magnitude when compared to plain stainless-steel electrodes, with a maximum power density of 24 mW m-2. Furthermore, the influence of medium solution in the electrolyte was also examined. Results demonstrate that microbial communities developed as biofilm in the anode were limited by substrate metabolic liability. The presence of a labile organic source (acetate) promoted an increase of one order of magnitude in cell performance. Overall, this study shows the potential of aligned CNTs to increase yield of MFCs. ; This work was supported by projects 2009SGR00185 of AGAUR of Generalitat de Catalunya and CTQ2009-14674-CO2-01 and MAT2010-20468 from MICINN of Spanish Government. The authors thank Centres Cientı´fics i Tecnolo` gics de la Universitat de Barcelona (CCiTUB) for measurement facilities and EDAR Sant Feliu de Llobregat for providing wastewater samples. ; Peer reviewed

11 páginas, 3 tablas, 5 figuras ; Root functional diversity of submerged vegetation exerts a major effect on nitrogen (N) cycling in lake sediments. This fact, however, is neglected in current N-balance models because the links between the engineering role of plants and in situ microbial N cycling are poorly understood. We hypothesized that macrophyte species with high root oxygen loss (ROL) capacity promote the highest denitrification because of a higher abundance of ammonia oxidizers and tighter coupling between nitrifiers and denitrifier communities. We sampled five small ultraoligotrophic shallow lakes with abundant macrophyte cover including sediments dominated either by Isoetes spp. (high ROL), mixed communities of natopotamids (low ROL), and unvegetated sandy sediments. At each site, we quantified denitrification (DNT) rates and proxies for the abundance of denitrifiers (nirS and nirK genes), and both ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) and the diversity of nirS-harboring bacteria. Vegetated sediments showed significantly higher abundances of N-cycling genes than bare sediments. Plant communities dominated by Isoetes generated sediments with higher redox and NO2 3 concentrations and significantly higher DNT rates than natopotamidsdominated landscapes. Accordingly, increasing DNT rates were observed along the gradient from low ROL plants-bare sediments-high ROL plants. Significantly higher abundance of the archaeal amoA gene was recorded in sediments colonized by high ROL plants unveiling a key biogeochemical role for AOA in coupling macrophyte landscape and ecosystem denitrification. ; MVC was supported by a Juan de la Cierva fellowship from the Spanish Office for Research (MINECO) and a Beatriu de Pin os from the Catalan Government. This research was granted by projects DARKNESS CGL2012-32747 (MINECO) to EOC and AQUAREST (OAPN 212/2010) to EG. EC, EOC and EG are members of the Environmental Changes Ecology Group (GECA), an Excellence Research Group (SGRDGR), of the Generalitat de Catalunya (Ref. 2014 SGR 1249. 2014–2017). ; Peer reviewed

Organic pollutants (OPs) are critically toxic, bioaccumulative and globally widespread. Moreover, several OPs negatively influence aquatic wildlife. Although bacteria are major drivers of the ocean carbon cycle and the turnover of vital elements, there is limited knowledge of OP effects on heterotrophic bacterioplankton. We therefore investigated growth and gene expression responses of the Baltic Sea model bacterium Rheinheimera sp. BAL341 to environmentally relevant concentrations of distinct classes of OPs in 2-h incubation experiments. During exponential growth, exposure to a mix of polycyclic aromatic hydrocarbons, alkanes and organophosphate esters (denoted MIX) resulted in a significant decrease (between 9% and 18%) in bacterial abundance and production compared with controls. In contrast, combined exposure to perfluorooctanesulfonic acids and perfluorooctanoic acids (denoted PFAS) had no significant effect on growth. Nevertheless, MIX and PFAS exposures both induced significant shifts in gene expression profiles compared with controls in exponential growth. This involved several functional metabolism categories (e.g. stress response and fatty acids metabolism), some of which were pollutant-specific (e.g. phosphate acquisition and alkane-1 monooxygenase genes). In stationary phase, only two genes in the MIX treatment were significantly differentially expressed. The substantial direct influence of OPs on metabolism during bacterial growth suggests that widespread OPs could severely alter biogeochemical processes governed by bacterioplankton. © 2019 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology. ; Funding text #1 Received 8 April, 2019; revised 15 May, 2019; accepted 15 May, 2019. *For correspondence. E-mail jarone.pinhassi@lnu.se; Tel. +46725949448 Microbial Biotechnology (2019) 12(5), 892–906 doi:10.1111/1751-7915.13441 Funding Information. This research was supported by the BONUS BLUEPRINT project, which has received funding from BONUS, the joint Baltic Sea research and development programme (Art 185), and the Swedish research council FORMAS. Funding was also provided through the Swedish governmental strong research programme EcoChange (FORMAS). Work by ECG and MVC was supported by a Fundación BBVA award to MVC (14_CMA_020) and by the Spanish MEIC through the project ISOMICS (CTM2015-65691-R). Funding text #2 We thank Josef Lautin for excellent technical assistance in the laboratory and Prof. Jordi Dachs for advice on organic pollutants. The authors would like to acknowledge the support from Science for Life Laboratory, the National Genomics Infrastructure, NGI, and Uppmax for providing assistance in massive parallel sequencing and computational infrastructure. The computations were performed on resources provided by SNIC through Uppsala Multidisciplinary Center for Advanced Computational Funding text #3 Science (UPPMAX) under project b2011200. The research was supported by the BONUS BLUEPRINT project, which has received funding from BONUS, the joint Baltic Sea research and development programme (Art 185), and the Swedish research council FORMAS. Funding was also provided through the Swedish governmental strong research programme EcoChange (FORMAS). Work by ECG and MVC was supported by a Fundación BBVA award to MVC (14_CMA_020) and by the Spanish MEIC through the project ISOMICS (CTM2015-65691-R). ; Peer reviewed

AbstractAlthough microbial degradation is a key sink of polycyclic aromatic hydrocarbons (PAH) in surface seawaters, there is a dearth of field-based evidences of regional divergences in biodegradation and the effects of PAHs on site-specific microbial communities. We compared the magnitude of PAH degradation and its impacts in short-term incubations of coastal Mediterranean and the Maritime Antarctica microbiomes with environmentally relevant concentrations of PAHs. Mediterranean bacteria readily degraded the less hydrophobic PAHs, with rates averaging 4.72 ± 0.5 ng L h−1. Metatranscriptomic responses showed significant enrichments of genes associated to horizontal gene transfer, stress response, and PAH degradation, mainly harbored by Alphaproteobacteria. Community composition changed and increased relative abundances of Bacteroidota and Flavobacteriales. In Antarctic waters, there was no degradation of PAH, and minimal metatranscriptome responses were observed. These results provide evidence for factors such as geographic region, community composition, and pre-exposure history to predict PAH biodegradation in seawater.

Thousands of semi-volatile hydrophobic organic pollutants (OPs) reach open oceans through atmospheric deposition, causing a chronic and ubiquitous pollution by anthropogenic dissolved organic carbon (ADOC). Hydrophobic ADOC accumulates in cellular lipids, inducing harmful effects on marine biota, and can be partially prone to microbial degradation. Unfortunately, their possible effects on microorganisms, key drivers of global biogeochemical cycles, remain unknown. We challenged coastal microbial communities from Ny-Ålesund (Arctic) and Livingston Island (Antarctica) with ADOC concentrations within the range of oceanic concentrations in 24 h. ADOC addition elicited clear transcriptional responses in multiple microbial heterotrophic metabolisms in ubiquitous groups such as Flavobacteriia, Gammaproteobacteria and SAR11. Importantly, a suite of cellular adaptations and detoxifying mechanisms, including remodelling of membrane lipids and transporters, was detected. ADOC exposure also changed the composition of microbial communities, through stimulation of rare biosphere taxa. Many of these taxa belong to recognized OPs degraders. This work shows that ADOC at environmentally relevant concentrations substantially influences marine microbial communities. Given that emissions of organic pollutants are growing during the Anthropocene, the results shown here suggest an increasing influence of ADOC on the structure of microbial communities and the biogeochemical cycles regulated by marine microbes. © 2019 Society for Applied Microbiology and John Wiley & Sons Ltd. ; This work was supported by BBVA Foundation for Researchers and Cultural Creative Workers award to MVC (14_CMA_020) and by the Spanish Ministerio de Economía y Competitividad (Ministry of Economy and Competitiveness, MEIC) through projects ISOMICS (CTM2015‐65691‐R), REMARCA (CTM2012‐34673) and SENTINEL (CTM2015‐70535‐P). ECG was supported by Agència de Gestió d'Ajuts Universtaris i Recerca, Generalitat de Catalunya (FI AGAUR) Scholarship, Generalitat de Catalunya Fellowship Program (Catalan Government, Generalitat de Catalunya). We thank MC. Fernández‐Pinos, M. Pizarro and G. Caballero for assistance with experimental settings, I. Forn, Dr. R. Massana and Dr. JM Gasol for support with CARD‐FISH and flow cytometry counts. Dr. C. Galbán‐Malagón (U. Andres‐Bello) for providing POP concentrations in polar seawater. The research group of Global Change and Genomic Biogeochemistry is supported by the Catalan Government (2017SGR800). ; Peer reviewed

The anthropogenic perturbation of the phosphorus (P) marine biogeochemical cycle due to synthetic organophosphorus compounds remains unexplored. The objective of this work was to investigate the microbial degradation of organophosphate triesters (OPEs), widely used as plasticizers and flame retardants, in seawater and their effects on the physiology and composition of microbial communities. Experiments were performed in July 2014 using surface seawater from the Blanes Bay Microbial Observatory (NW Mediterranean) to which OPEs were added at environmentally relevant concentrations. The concentrations of OPEs in the dissolved-phase generally decreased after 24 hours of incubation at in situ conditions. The fitted first order reaction constants were significantly different than zero for the trihaloalkyl phosphate, tris(2-chloroethyl) phosphate and trialyl phosphate tricresyl phosphate. In general, OPEs triggered an increase of the percentage of actively respiring bacteria, total bacterial activity, and the number of low-nucleic acid bacteria, and a decrease in the percentage of membrane-compromised bacteria. Members of some bacterial groups, in particular Flavobacteria, increased their specific activity, indicating that seawater contains bacteria with the potential to degrade OPEs. In aged seawater that was presumably depleted of labile dissolved organic carbon and inorganic P, alkaline phosphatase activities significantly decreased when OPEs were added, indicating a relief on P stress, consistent with the role of OPEs as potential P sources. © 2019, The Author(s). ; This work was supported by Fundación BBVA award to MVC and by the Spanish MEIC through projects ISOMICS (CTM2015-65691-R) and REMEI (CTM2015-70340-R). MS was supported by grant EcoRARE (CTM2014-60467-JIN), funded by the Spanish Government and the European Regional Development Fund (ERDF) and a Viera y Clavijo contract funded by the ACIISI and the ULPGC. The research group of Global Change and Genomic Biogeochemistry is supported by the Catalan Goverment (2017SGR800). We thank J Castro-Jimenez for support on the OPE analyses. MVC is indebted to J Pinhassi for support. ; Peer reviewed

Thousands of man-made synthetic chemicals are released to oceans and compose the anthropogenic dissolved organic carbon (ADOC). Little is known about the effects of this chronic pollution on marine microbiome activities. In this study, we measured the pollution level at three sites in the Northeast Subarctic Pacific Ocean (NESAP) and investigated how mixtures of three model families of ADOC at different environmentally relevant concentrations affected naturally occurring marine bacterioplankton communities' structure and metabolic functioning. The offshore northernmost site (North) had the lowest concentrations of hydrocarbons, as well as organophosphate ester plasticizers, contrasting with the two other continental shelf sites, the southern coastal site (South) being the most contaminated. At North, ADOC stimulated bacterial growth and promoted an increase in the contribution of some Gammaproteobacteria groups (e.g. Alteromonadales) to the 16 rRNA pool. These groups are described as fast responders after oil spills. In contrast, minor changes in South microbiome activities were observed. Gene expression profiles at Central showed the coexistence of ADOC degradation and stress-response strategies to cope with ADOC toxicities. These results show that marine microbial communities at three distinct domains in NESAP are influenced by background concentrations of ADOC, expanding previous assessments for polar and temperate waters. ; This publication is dedicated to the memory of our missed friend, mentor and colleague, Prof. Ronald P. Kiene. The authors thank the Capitan and crew of the R/V Oceanus. This work was funded by the Spanish MEIC through projects ISOMICS (CTM2015-65691-R) and SENTINEL (CTM2015-70535-P). The authors sincerely thank J.M. Gasol for support with flow cytometry counts and I. Forn for microscopy counts. The research group of Global Change and Genomic Biogeochemistry is supported by the Catalan Government (2017SGR800). IDAEA-CSIC is a Centre of Excellence Severo Ochoa (Spanish Ministry of Science and Innovation, Project CEX2018-000794-S). ; Peer reviewed