Bioplastic degradation and assimilation processes by a novel bacterium isolated from the marine plastisphere.

Biosourced and biodegradable plastics offer a promising solution to reduce environmental impacts of plastics for specific applications. Here, we report a novel bacterium named Alteromonas plasticoclasticus MED1 isolated from the marine plastisphere that forms biofilms on foils of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Experiments of degradation halo, plastic matrix weight loss, bacterial oxygen consumption and heterotrophic biosynthetic activity showed that the bacterial isolate MED1 is able to degrade PHBV and to use it as carbon and energy source.

Open science resources from the Tara Pacific expedition across coral reef and surface ocean ecosystems.

The Tara Pacific expedition (2016-2018) sampled coral ecosystems around 32 islands in the Pacific Ocean and the ocean surface waters at 249 locations, resulting in the collection of nearly 58 000 samples. The expedition was designed to systematically study warm-water coral reefs and included the collection of corals, fish, plankton, and seawater samples for advanced biogeochemical, molecular, and imaging analysis. Here we provide a complete description of the sampling methodology, and we explain how to explore and access the different datasets generated by the expedition.

Sponge organic matter recycling: Reduced detritus production under extreme environmental conditions.

Sponges are a key component of coral reef ecosystems and play an important role in carbon and nutrient cycles. Many sponges are known to consume dissolved organic carbon and transform this into detritus, which moves through detrital food chains and eventually to higher trophic levels via what is known as the sponge loop. Despite the importance of this loop, little is known about how these cycles will be impacted by future environmental conditions.

Development of a Frugal, In Situ Sensor Implementing a Ratiometric Method for Continuous Monitoring of Turbidity in Natural Waters.

Turbidity is a commonly used indicator of water quality in continental and marine waters and is mostly caused by suspended and colloidal particles such as organic and inorganic particles. Many methods are available for the measurement of turbidity, ranging from the Secchi disk to infrared light-based benchtop or in situ turbidimeters as well as acoustic methods. The operational methodologies of the large majority of turbidity instruments involve the physics of light scattering and absorption by suspended particles when light is passed through a sample.

Microbial Diversity and Activity During the Biodegradation in Seawater of Various Substitutes to Conventional Plastic Cotton Swab Sticks.

The European Parliament recently approved a new law banning single-use plastic items for 2021 such as plastic plates, cutlery, straws, cotton swabs, and balloon sticks. Transition to a bioeconomy involves the substitution of these banned products with biodegradable materials. Several materials such as polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), poly(butylene succinate) (PBS), polyhydroxybutyrate-valerate (PHBV), Bioplast, and Mater-Bi could be good candidates to substitute cotton swabs, but their biodegradability needs to be tested under marine conditions.

Mismatched dynamics of dissolved organic carbon and chromophoric dissolved organic matter in the coastal NW Mediterranean Sea.

Coastal marine ecosystems are strongly influenced by different occasional events, such as intense winds, mixing, rain and river discharges. These events can directly or indirectly cause changes in dissolved organic matter (DOM) quality through a cascade of different biotic and abiotic processes. Changes in DOM quality are often associated with changes in DOM optical properties.

Submarine karstic springs as a source of nutrients and bioactive trace metals for the oligotrophic Northwest Mediterranean Sea.

Groundwater springs in karstified carbonate aquifers are known to transport carbon, nutrients and trace elements to the coastal ocean. The biogeochemical significance of submarine karstic springs and their impact on coastal primary production are often difficult to quantify. We investigated several karstic springs, including the first-order Port-Miou spring, in an urbanized watershed that is also severely impacted by sewage effluent (Calanques of Marseille-Cassis, France).

Microbial Ecotoxicology of Marine Plastic Debris: A Review on Colonization and Biodegradation by the "Plastisphere".

Over the last decades, it has become clear that plastic pollution presents a global societal and environmental challenge given its increasing presence in the oceans. A growing literature has focused on the microbial life growing on the surfaces of these pollutants called the "plastisphere," but the general concepts of microbial ecotoxicology have only rarely been integrated. Microbial ecotoxicology deals with (i) the impact of pollutants on microbial communities and inversely (ii) how much microbes can influence their biodegradation.

Nanoplanktonic diatoms are globally overlooked but play a role in spring blooms and carbon export.

Diatoms are one of the major primary producers in the ocean, responsible annually for ~20% of photosynthetically fixed CO on Earth. In oceanic models, they are typically represented as large (>20 µm) microphytoplankton. However, many diatoms belong to the nanophytoplankton (2-20 µm) and a few species even overlap with the picoplanktonic size-class (<2 µm).

Multicontamination phenomena occur more often than expected in Mediterranean coastal watercourses: Study case of the Têt River (France).

Contaminants found in watercourses are not only the result of anthropogenic activities but also depend on river's seasonal hydrodynamics. This is particularly true in Mediterranean climate regions where long dry periods are interrupted by strong rainfalls. Storm events remobilize particles from soils and sediments and, as a consequence, the load of particulate matter in rivers can be quite considerable, severely affecting water quality.

Impact of an intense water column mixing (0-1500 m) on prokaryotic diversity and activities during an open-ocean convection event in the NW Mediterranean Sea.

Open-ocean convection is a fundamental process for thermohaline circulation and biogeochemical cycles that causes spectacular mixing of the water column. Here, we tested how much the depth-stratified prokaryotic communities were influenced by such an event, and also by the following re-stratification. The deep convection event (0-1500 m) that occurred in winter 2010-2011 in the NW Mediterranean Sea resulted in a homogenization of the prokaryotic communities over the entire convective cell, resulting in the predominance of typical surface Bacteria, such as Oceanospirillale and Flavobacteriales.

Influence of PAHs among other coastal environmental variables on total and PAH-degrading bacterial communities.

We evaluated the relative impact of anthropogenic polycyclic aromatic hydrocarbons (PAHs) among biogeochemical variables on total, metabolically active, and PAH bacterial communities in summer and winter in surface microlayer (SML) and subsurface seawaters (SSW) across short transects along the NW Mediterranean coast from three harbors, one wastewater effluent, and one nearshore observatory reference site. At both seasons, significant correlations were found between dissolved total PAH concentrations and PAH-degrading bacteria that formed a gradient from the shore to nearshore waters. Accumulation of PAH degraders was particularly high in the SML, where PAHs accumulated.

Top-Down Control of Diesel-Degrading Prokaryotic Communities.

Biostimulation through the addition of inorganic nutrients has been the most widely practiced bioremediation strategy in oil-polluted marine waters. However, little attention has so far been paid to the microbial food web and the impact of top-down control that directly or indirectly influences the success of the bioremediation. We designed a mesocosm experiment using pre-filtered (<50 μm) surface seawater from the Bay of Banyuls-sur-Mer (North-Western Mediterranean Sea) and examined the top-down effect exerted by heterotrophic nanoflagellates (HNF) and virus-like particles (VLP) on prokaryotic abundance, activity and diversity in the presence or absence of diesel fuel.

'Rare biosphere' bacteria as key phenanthrene degraders in coastal seawaters.

By coupling DNA-SIP and pyrosequencing approaches, we identified Cycloclasticus sp. as a keystone degrader of polycyclic aromatic hydrocarbons (PAH) despite being a member of the 'rare biosphere' in NW Mediterranean seawaters. We discovered novel PAH-degrading bacteria (Oceanibaculum sp.

Diversity of total and active free-living vs. particle-attached bacteria in the euphotic zone of the NW Mediterranean Sea.

The structure of the total and metabolically active communities of attached and free-living bacteria were analysed in the euphotic zone in the NW Mediterranean Sea with the use of DNA- and RNA-derived capillary electrophoresis single-strand conformation polymorphism fingerprinting. More than half (between 52% and 69%) of the DNA-derived operational taxonomic units (OTUs) were common in both attached and free-living fractions in the euphotic layer, suggesting an exchange or co-occurrence between them. However, analysis targeting 16S rRNA showed that only some of them were found in the dominant active bacterial pool.

Ultraviolet radiation in the rhône river lenses of low salinity and in marine waters of the northwestern mediterranean sea: attenuation and effects on bacterial activities and net community production.

The high content in nutrients of freshwater outflows induces highly productive and buoyant plumes spreading over marine waters (MW). As a consequence, the growth of organisms developing in these low-salinity waters (LSW) might be potentially affected by UV-R (280-400 nm). This study investigated the penetration of UV-R and its impact on net community production (NCP) and bacterial protein (B(PROT)S) and DNA (B(DNA)S) synthesis in mesotrophic-LSW formed from the Rhône River and in oligotrophic MW of the Northwestern Mediterranean Sea (Gulf of Lions) in May 2006.

Export of dissolved organic matter in relation to land use along a European climatic gradient.

The terrestrial export of dissolved organic matter (DOM) is associated with climate, vegetation and land use, and thus is under the influence of climatic variability and human interference with terrestrial ecosystems, their soils and hydrological cycles. We present a data-set including catchments from four areas covering the major climate and land use gradients within Europe: a forested boreal zone (Finland), a temperate agricultural area (Denmark), a wet and temperate mountain region in Wales, and a warm Mediterranean catchment draining into the Gulf of Lyon. In all study areas, DOC (dissolved organic carbon) was a major fraction of DOM, with much lower proportions of DON (dissolved organic nitrogen) and DOP (dissolved organic phosphorus).