Differentiation of bacterial communities on five common plastics after six days of exposure to Caribbean coastal waters

Plastic pollution in coastal areas, particularly in subtropical and tropical regions, remains a pervasive environmental issue. Marine plastic debris provides an artificial surface that rapidly accumulates a dynamic microbial biofilm upon entering the marine ecosystem. Especially the early stages of colonization are critical in shaping the microbial community. This study investigates the early microbial colonization, in less than a week, on five different plastic polymers in Caribbean coastal waters through 16S rRNA gene amplicon sequencing. We discovered shared bacterial taxa among the various plastic polymers and sampling timepoints, with dominant orders being Flavobacteriales, Rhodobacterales, Rhizobiales, and Pseudomonadales. Statistical analysis confirmed significant differences in community composition between the two sampling points, with polystyrene exhibiting a distinct microbial community on day 6 compared to polyethylene, polypropylene, and nylon. We found the same for polyethylene compared to nylon and polyethylene-terephthalate. Further examination identified 47 genera responsible for these differences, primarily belonging to the phyla Proteobacteria and Bacteroidota. Our data indicate an influence of both environmentally related stochastic processes and plastic-related specific factors during early colonization. Interestingly, we noticed an increase in the relative abundance of hydrocarbon and potentially plastic-degrading bacteria (PDB) from 12.4 to 34.5 % between the first and sixth day, suggesting their vital role in shaping the epiplastic community. Notably, some identified PDB have been reported to degrade the specific polymers studied, thus the monitored increase in relative abundance supports their role in plastic degradation. However, more research is required to fully understand their functioning and potential role in the epiplastic community. Our study provides insights into the prokaryotic colonization of marine plastics in the Caribbean basin, where to date studies have been limited despite high pollution rates

Biodegradable plastics in Mediterranean coastal environments feature contrasting microbial succession

Plastic pollution of the ocean is a top environmental concern. Biodegradable plastics present a potential “solution” in combating the accumulation of plastic pollution, and their production is currently increasing. While these polymers will contribute to the future plastic marine debris budget, very little is known still about the behavior of biodegradable plastics in different natural environments. In this study, we molecularly profiled entire microbial communities on laboratory confirmed biodegradable polybutylene sebacate-co-terephthalate (PBSeT) and polyhydroxybutyrate (PHB) films, and non-biodegradable conventional low-density polyethylene (LDPE) films that were incubated in situ in three different coastal environments in the Mediterranean Sea. Samples from a pelagic, benthic, and eulittoral habitat were taken at five timepoints during an incubation period of 22 months. We assessed the presence of potential biodegrading bacterial and fungal taxa and contrasted them against previously published in situ disintegration data of these polymers. Scanning electron microscopy imaging complemented our molecular data. Putative plastic degraders occurred in all environments, but there was no obvious “core” of shared plastic-specific microbes. While communities varied between polymers, the habitat predominantly selected for the underlying communities. Observed disintegration patterns did not necessarily match community patterns of putative plastic degraders

Plastic photodegradation under simulated marine conditions

Ocean plastic pollution is a problem of increasing magnitude; yet, the amount of plastic at the sea surface is much lower than expected. Solar ultraviolet (UV) radiation can induce photodegradation, but its importance in determining the longevity of floating plastic remains unconstrained. Here, we measured photodegradation rates of different plastic types slightly larger than microplastics (virgin polymers and floating plastic debris) under simulated marine conditions. UV irradiation caused all plastic types to leach dissolved organic carbon, and to a lesser degree carbon dioxide, carbon monoxide, methane, and other hydrocarbon gases. The release of photodegradation products translates to degradation rates of 1.7–2.3 % yr−1 of the tested plastic particles normalized to conditions as found in the subtropical surface ocean. Modelling the accumulation of floating plastic debris, our results show that solar UV radiation could already have degraded 7 to 22 % of all floating plastic that has ever been released to the sea

A stable isotope assay with 13C-labeled polyethylene to investigate plastic mineralization mediated by Rhodococcus ruber

Methods that unambiguously prove microbial plastic degradation and allow for quantification of degradation rates are necessary to constrain the influence of microbial degradation on the marine plastic budget. We developed an assay based on stable isotope tracer techniques to determine microbial plastic mineralization rates in liquid medium on a lab scale. For the experiments, 13C-labeled polyethylene (13C-PE) particles (irradiated with UV-light to mimic exposure of floating plastic to sunlight) were incubated in liquid medium with Rhodococcus ruber as a model organism for proof of principle. The transfer of 13C from 13C-PE into the gaseous and dissolved CO2 pools translated to microbially mediated mineralization rates of up to 1.2 % yr−1 of the added PE. After incubation, we also found highly 13C-enriched membrane fatty acids of R. ruber including compounds involved in cellular stress responses. We demonstrated that isotope tracer techniques are a valuable tool to detect and quantify microbial plastic degradation

Biodegradable plastics in Mediterranean coastal environments feature contrasting microbial succession

Plastic pollution of the ocean is a top environmental concern. Biodegradable plastics present a potential “solution” in combating the accumulation of plastic pollution, and their production is currently increasing. While these polymers will contribute to the future plastic marine debris budget, very little is known still about the behavior of biodegradable plastics in different natural environments. In this study, we molecularly profiled entire microbial communities on laboratory confirmed biodegradable polybutylene sebacate-co-terephthalate (PBSeT) and polyhydroxybutyrate (PHB) films, and non-biodegradable conventional low-density polyethylene (LDPE) films that were incubated in situ in three different coastal environments in the Mediterranean Sea. Samples from a pelagic, benthic, and eulittoral habitat were taken at five timepoints during an incubation period of 22 months. We assessed the presence of potential biodegrading bacterial and fungal taxa and contrasted them against previously published in situ disintegration data of these polymers. Scanning electron microscopy imaging complemented our molecular data. Putative plastic degraders occurred in all environments, but there was no obvious “core” of shared plastic-specific microbes. While communities varied between polymers, the habitat predominantly selected for the underlying communities. Observed disintegration patterns did not necessarily match community patterns of putative plastic degraders

Plastic photodegradation under simulated marine conditions

Ocean plastic pollution is a problem of increasing magnitude; yet, the amount of plastic at the sea surface is much lower than expected. Solar ultraviolet (UV) radiation can induce photodegradation, but its importance in determining the longevity of floating plastic remains unconstrained. Here, we measured photodegradation rates of different plastic types slightly larger than microplastics (virgin polymers and floating plastic debris) under simulated marine conditions. UV irradiation caused all plastic types to leach dissolved organic carbon, and to a lesser degree carbon dioxide, carbon monoxide, methane, and other hydrocarbon gases. The release of photodegradation products translates to degradation rates of 1.7–2.3 % yr−1 of the tested plastic particles normalized to conditions as found in the subtropical surface ocean. Modelling the accumulation of floating plastic debris, our results show that solar UV radiation could already have degraded 7 to 22 % of all floating plastic that has ever been released to the sea

Gender differences in characteristics of physical and sexual victimization in patients with dual diagnosis: a cross-sectional study

Patients with substance use disorders and co-occurring mental health disorders are vulnerable to violent victimization. However, no evidence-based interventions are available to reduce patients' vulnerability. An exploration of the characteristics of physical and sexual violence can provide valuable information to support the development of interventions for these patients. This study aimed to examine gender differences in characteristics of violent victimization in patients with dual diagnosis. In this cross-sectional survey study recent incidents of physical and sexual assault were examined with the Safety Monitor in 243 patients with dual diagnosis. Chi-square tests were used to examine gender differences in the prevalence of physical and sexual victimization. Fisher's exact tests and Fisher-Freeman-Halton exact tests were used to determine whether there were significant differences between victimized men and women with regard to perpetrators, locations, reporting to the police and speaking about the assault with others. There was no significant difference in the prevalence of physical violence in men (35%) and women (47%) with dual diagnosis. There was a significant association between gender of the victim and type of perpetrator (P < .001). Men were most often physically abused by a stranger or an acquaintance, whereas women were most frequently abused by an (ex)partner. Sexual violence was more prevalent in women (29%) compared to men (4%) (P < .001). Patients with dual diagnosis were unlikely to report incidents of physical abuse and sexual assault to the police and to speak about it with caregivers. Characteristics of physical violence are different for men and women with dual diagnosis. Women with dual diagnosis are more often victims of sexual violence compared to men. Interventions aimed at reducing patients' vulnerability for victimization should take gender differences into accoun

Les Tablettes d'Avignon et de Provence : revue hebdomadaire illustrée de propagande régionaliste par Avignon, centre de tourisme

07 mai 19391939/05/07 (N677).Appartient à l’ensemble documentaire : PACA

Microbial Communities on Plastic Polymers in the Mediterranean Sea

Plastic particles in the ocean are typically covered with microbial biofilms, but it remains unclear whether distinct microbial communities colonize different polymer types. In this study, we analyzed microbial communities forming biofilms on floating microplastics in a bay of the island of Elba in the Mediterranean Sea. Raman spectroscopy revealed that the plastic particles mainly comprised polyethylene (PE), polypropylene (PP), and polystyrene (PS) of which polyethylene and polypropylene particles were typically brittle and featured cracks. Fluorescence in situ hybridization and imaging by high-resolution microscopy revealed dense microbial biofilms on the polymer surfaces. Amplicon sequencing of the 16S rRNA gene showed that the bacterial communities on all plastic types consisted mainly of the orders Flavobacteriales, Rhodobacterales, Cytophagales, Rickettsiales, Alteromonadales, Chitinophagales, and Oceanospirillales. We found significant differences in the biofilm community composition on PE compared with PP and PS (on OTU and order level), which shows that different microbial communities colonize specific polymer types. Furthermore, the sequencing data also revealed a higher relative abundance of archaeal sequences on PS in comparison with PE or PP. We furthermore found a high occurrence, up to 17% of all sequences, of different hydrocarbon-degrading bacteria on all investigated plastic types. However, their functioning in the plastic-associated biofilm and potential role in plastic degradation needs further assessment