The global accumulation of plastic debris in marine ecosystems is continually increasing. Understanding the interaction between these debris and the bacterial biofilm on their surface is essential, particularly with regard to potential human pathogenic bacteria (PHPB). In this meta-analysis, we re-evaluated 16S rRNA metabarcoding data from 35 plastisphere-related studies, published up to late 2022. We compared the bacteriomes of plastics and other marine substrates, identifying PHPB associated with each type of substrate. PHPB were enriched in the plastisphere compared to the surrounding water but did not appear more abundant nor richer in than in other marine solid substrates. Nevertheless, we described a distinctive PHPB signature associated with plastics, including Vibrionaceae bacteria (5 % of the whole plastisphere) and biomarkers such as Staphylococcus haemolyticus. The contribution of other marine substrates to plastic PHPB was quantified and we found that shell and wood substrates were potential sources of PHPB for plastics. Our results suggest that both plastics and other marine solid substrates could serve as reservoirs for PHPB. However, plastics convey specific PHPB communities, and due to their ubiquity and persistence in marine ecosystems, plastic debris poses a higher risk as fomites compared to other substrates.

International audience | Tillandsia genus belongs to the Bromeliaceae family plants and some species display active or passive biomonitoring capacities in their natural habitat as it has been described mostly in the American continent. However, Tillandsia aeranthos (Loisiel.) Desf. and Tillandsia bergeri Mez have never been studied for their metal air pollution biomonitor potential. A recent study conducted in our laboratory brought to light the maximum capacity of elements bioconcentration into these two species leaves. The aim of the present study is to determine if T. aeranthos and T. bergeri acclimated to Southern/European region are good biomonitors for airborne elements pollution. Twelve elements were chosen to evaluate the biomonitoring potential (As, Ba, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Ti and Zn). After sampling, the content of the twelve elements in leaves was measured by Inductively Coupled Plasma-Optical Emission Spectrometry and Inductively Coupled Plasma-Mass Spectrometry. Data sets were treated according to sampling sites by box plots over time and Principal Component Analysis. The results showed differences between the two species, with T. bergeri possessing a higher capacity in accumulating elements than T. aeranthos. Fe, Zn and Co showed a higher contribution in the accumulation process in the two Tillandsia species leading to the hypothesis of a good affinity of the two species with these elements. Values obtained for five elements (As, Cr, Ni, Pb and Zn) were compared with values recorded by a monitoring station close to sampling sites showing the efficiency of these two Tillandsia species as biomonitors. High Co accumulation rates obtained in both Tillandsia species were particularly intriguing but could not be rationalized as this metal is not currently monitored by air pollution station in this region. T. aeranthos and T. bergeri proved their efficiency for the biomonitoring of elements air pollution, especially for Co, Fe and Zn.

International audience

International audience | The reuse of treated wastewater (TWW) for irrigation is widely applied to alleviate pressure on freshwater resources. However, TWW contains antibiotics that once in soils, can exert selective pressure, promoting the emergence and spread of antimicrobial resistance (AMR) in the environment. Current environmental risk assessments for antibiotic residues rely on indicators such as Predicted No Effect Concentrations (PNECs), usually determined in liquid media. These PNECs aim to predict antibiotic concentrations that may promote resistance in the environment. Given the complexity of soil matrices, few studies have established PNEC values for soil, which likely differ significantly from aquatic environments.To address this gap, we developed a simplified experimental model using soil microcosms irrigated with TWW and the antibiotic sulfamethoxazole (SMX) to estimate threshold concentrations favouring resistance transfer or/and emergence within the soil microbiome. We identified SMX concentrations between 0.01 and 0.1 mg/kgdry soil that likely increased the abundance of sulfonamide resistance genes in soil. A time window of 1 to 7 days post-exposure showed a temporary rise in sul1 and intl1 gene abundance (over 1 log/soil 16S rDNA), the appearance of SMX transformation products, and an increase in some Rhodocyclaceae. After 1.5 months of incubation and complete SMX transformation, the relative abundance of sul1 and intl1 remained about 0.5 log higher than in SMX-free controls and soils with SMX levels below 0.1 mg/kg dry soil. A persistent transformation product, 4-N-glucuronide-SMX, was also observed.Here, the estimated PNEC for SMX in soil, between 0.01 and 0.1 mg/kg, exceeds typical SMX concentrations found in soils exposed to TWW. This may suggest low impact on resistance selection for this compound in the context of TWW exposure. However further studies on other soils, water, and antibiotics need to be conducted to expand our knowledge on soil PNECs.

International audience | <div><p>Aquaculture is crucial in meeting global seafood demand; however, intensification often leads to bacterial diseases that threaten productivity. Dicentrarchus labrax, a key species in European aquaculture, is highly vulnerable to vibriosis, primarily caused by Vibrio harveyi. This study investigates genetic profiles associated with vibriosis by analyzing V. harveyi strains from a seabass farm during 2022 vibriosis outbreaks. Sampling from biofilm and water environments yielded 946 bacterial isolates, of which 56 were identified as V. harveyi using MALDI-TOF MS. ERIC-PCR genotyping revealed four distinct profiles. Despite observing variability in the presence of the 80 tested virulence genes, the overall genetic variation among these profiles was not pronounced. Notably, no single genotypic profile was linked to vibriosis. These findings suggest that the presence of virulence genes alone may not predict disease outbreaks, thus highlighting the need for future research on environmental and transcriptional factors to improve disease control in aquaculture systems.</p></div>

International audience | A considerable proportion of marine plastic pollution consists of abandoned, lost, or otherwise discarded fishing gear (ALDFG). Whether still intact or break down into fragments, ALDFG is a widespread, enduring problem, and as such, it represents an ideal case for the use of citizen science. The Fish&amp;Click program proposes a mobile application and website to enable non-specialist observers, such as walkers, divers, or sailors, to record their sightings of ALDFG. The simple interface allows the user to characterize found gear without any expert knowledge, and an analysis of these data can shed light on the magnitude and spatio-temporal composition of the ALDFG phenomenon. This report presents the results and feedback from the first two years of Fish&amp;Click, from May 2020 to June 2022, in the north of the Bay of Biscay, Celtic Sea, and English Channel. In addition to a database cleaning procedure, we defined an ad hoc methodology for analyzing these non-standardized data. Using this, we found that the types and quantities of found gear differ between sea and shore locations and were also different from one region to another. We discuss the pros and cons of this citizen-science program, as well as the potential for improvements that might help to mitigate pollution by ALDFG.