Project description:The presence of plastic and microplastic within the oceans as well as in marine flora and fauna have caused a multitude of problems which have been topic of numerous investigations for many years. However, their impact on human health remains largely unknown. Such plastic and microplastic particles have been detected in blood and placenta, underlining their ability to enter the human body. Plastics also contain other compounds, such as plasticizers, antioxidants, or dyes, whose impact on human health is currently being studied. Critical enzymes within the metabolism of endogenous molecules, especially of xenobiotics, are the cytochrome P450 monooxygenases (CYPs). Although their importance in maintaining cellular balance has been confirmed, their interactions with plastics and related products are poorly understood. In this study, the possible relationship between different plastic-related compounds and CYP3A4 as one of the most important CYPs was analyzed using hepatic cells overexpressing this enzyme. Beginning with virtual compound screening and molecular docking of more than 1,000 plastic-related compounds, several candidates were identified to interact with CYP3A4. In a second step, RNA-sequencing was used to study in detail the transcriptome-wide gene expression levels affected by the selected compounds. The results showed that three candidate molecules (2,2'-methylene bis(6-tert-butyl-4-methylphenol, 1,1-bis(3,5-di-tert-butyl-2-hydroxyphenyl)ethane, and 2,2'-methylene bis(6-cyclohexyl-4-methylphenol) had an excellent binding affinity to CYP3A4 in silico as well as cytotoxic effects and interactions with several metabolic pathways in vitro. We identified common pathways influenced by all three selected plastic-related compounds. In particular, the suppression of pathways related to mitosis and ‘DNA-templated DNA replication’. Furthermore, several mis-regulated metabolic and inflammation-related pathways were identified, suggesting the induction of hepatotoxicity at different levels. These findings imply that these compounds may cause problems in the liver, which could subsequently affect the entire organism.
Project description:To characterize the taxonomic and functional diversity of biofilms on plastics in marine environments, plastic pellets (PE and PS, ø 3mm) and wooden pellets (as organic control) were incubated at three stations: at the Baltic Sea coast in Heiligendamm (coast), in a dead branch of the river Warnow in Warnemünde (inlet), and in the Warnow estuary (estuary). After two weeks of incubation, all pellets were frozen for subsequent metagenome sequencing and metaproteomic analysis. Biofilm communities in the samples were compared on multiple levels: a) between the two plastic materials, b) between the individual incubation sites, and c) between the plastic materials and the wooden control. Using a semiquantitative approach, we established metaproteome profiles, which reflect the dominant taxonomic groups as well as abundant metabolic functions in the respective samples.
Project description:Biodegradable plastics are one possible solution for reducing plastic waste, yet the mechanisms and organisms involved in their degradation in the aquatic environment remain understudied. In this study, we have enriched a microbial community from North Sea water and sediment, capable of growing on the polyester poly(butylene succinate). This culture was grown on two other biodegradable polyesters, polycaprolactone and ecovio® FT (a PBAT-based blended biodegradable plastic), and the differences between community structure and activity on these three polymers were determined by metagenomics and metaproteomics. We have seen that the plastic supplied drives the community structure and activity. Setups growing on ecovio® FT were more diverse, yet showed the lowest degradation, while poly(butylene succinate) and polycaprolactone resulted in a less diverse community but much higher degradation efficiencies. The dominating species were Alcanivorax sp., Thalassobius sp., or Pseudomonas sp., depending on the polymer supplied. Furthermore, we have observed that Gammaproteobacteria were more abundant and active within the biofilm and Alphaproteobacteria within the free-living fraction of the enrichments. Two of the three PETase-like enzymes isolated were expressed as tandems (Ple -tan1 &Ple – tan2) and all three were produced by Pseudomonas sp. Of those, Ple-tan1 was most active on all three substrates and also the most thermostable. Overall, we could show that all three plastics investigated can be mineralized by bacteria naturally occurring within the marine environment and characterize some of the enzymes involved in the degradation process.
Project description:Macroalgae contribute substantially to primary production in coastal ecosystems. Their biomass, mainly consisting of polysaccharides, is cycled into the environment by marine heterotrophic bacteria (MHB), using largely uncharacterized mechanisms. In Zobellia galactanivorans, we discovered and characterized the complete catabolic pathway for carrageenans, major cell wall polysaccharides of red macroalgae, providing a model system for carrageenan utilization by MHB. We further demonstrate that carrageenan catabolism relies on a multifaceted carrageenan-induced regulon, including a non-canonical polysaccharide utilization locus (PUL) and several distal genes. The genetic structure of the carrageenan utilization system is well conserved in marine Bacteroidetes, but modified in other MHB phyla. The core system is completed by additional functions which can be assumed by non-orthologous genes in different species. This complex genetic structure is due to multiple evolutionary events including gene duplications and horizontal gene transfers. These results allow for an extension on the definition of bacterial PUL-mediated polysaccharide digestion.
Project description:Fomitiporia mediterranea (Fmed) is one of the main fungal species found in grapevine wood rot, also called “amadou”, one of the most typical symptoms of grapevine trunk disease Esca. This fungus is functionally classified as a white-rot, able to degrade all wood structure polymers, i.e., hemicelluloses, cellulose, and the most recalcitrant component, lignin. Specific enzymes are secreted by the fungus to degrade those components, namely carbohydrate active enzymes for hemicelluloses and cellulose, which can be highly specific for given polysaccharide, and peroxidases, which enable white-rot to degrade lignin, with specificities relating to lignin composition as well. Furthermore, besides polymers, a highly diverse set of metabolites often associated with antifungal activities is found in wood, this set differing among the various wood species. Wood decayers possess the ability to detoxify these specific extractives and this ability could reflect the adaptation of these fungi to their specific environment. The aim of this study is to better understand the molecular mechanisms used by Fmed to degrade wood structure, and in particular its potential adaptation to grapevine wood. To do so, Fmed was cultivated on sawdust from different origins: grapevine, beech, and spruce. Carbon mineralization rate, mass loss, wood structure polymers contents, targeted metabolites and secreted proteins were measured. We used the well-known white-rot model Trametes versicolor for comparison. Whereas no significant degradation was observed with spruce, a higher mass loss was measured on Fmed grapevine culture compared to beech culture. Moreover, on both substrates, a simultaneous degradation pattern and the degradation of wood extractives were demonstrated, and proteomic analyses identified a relative overproduction of oxidoreductases involved in lignin and extractive degradation on grapevine cultures, and only few differences in carbohydrate active enzymes. These results could explain at least partially the adaptation of Fmed to grapevine wood structural composition compared to other wood species and suggest that other biotic and abiotic factors should be considered to fully understand the potential adaptation of Fmed to its ecological niche.
Project description:Although the biodegradation of biodegradable plastics in soil and compost is well-studied, there is little knowledge on the metabolic mechanisms of synthetic polymers degradation by marine microorganisms. Here, we present a multiomics study to elucidate the biodegradation mechanism of a commercial aromatic-aliphatic copolyester film by a marine microbial enrichment culture. The plastic film and each monomer can be used as sole carbon source. Our analysis showed that the consortium synergistically degrades the polymer, different degradation steps being performed by different members of the community. Analysis of gene expression and translation profiles revealed that the relevant degradation processes in the marine consortium are closely related to poly(ethylene terephthalate) biodegradation from terrestrial microbes. Although there are multiple genes and organisms with the potential to perform a degradation step, only a few of these are active during biodegradation. Our results elucidate the potential of marine microorganisms to mineralize biodegradable plastic polymers and describe the mechanisms of labor division within the community to get maximum energetic yield from a complex synthetic substrate.
Project description:Plastics are one of the most preoccupying emerging pollutants. Macroplastics released in the environment degrade into microplastics and nanoplastics. Because of their small size, these micro and nano plastic particles can enter the food chain and, in addition to their ecotoxicological effects, contaminate humans with still unknown biological effects. Plastics being particulate pollutants, they are handled in the human body by scavenger cells such as macrophages, which are important players in the immune system. In order to get a better appraisal of the effects of plastic particles on macrophages, we have studied the effects of unmodified polystyrene particles of 0.1, 1 and 10 micrometers of diameter, by a combination of proteomics and targeted approaches. Proteomics showed important adaptive changes of the proteome in response to exposure to plastics, with more than one third of the detected proteins showing a significance change in their abundance in response to cell exposure to at least one plastic beads size. These changes affected for example mitochondrial, lysosomal or cytoskeletal proteins. Although an increase in the mitochondrial transmembrane potential was detected in response to 10 micrometer beads, no alteration in cell viability was observed. Similarly, no lysosomal dysfunction and no alteration in the phagocytic capability of the cells was observed in response to exposure to plastic. When the inflammatory response was examined, no increase in the secretion of tumor necrosis factor or interleukin 6 was observed. Oppositely, the secretion of these cytokines in response to lipopolysaccharide was observed after exposure to plastic, which suggested a decreased ability of macrophages to respond to bacterial infection. In conclusion, these results provide a better understanding of the responses of macrophages to exposure to polystyrene particles of different sizes.
Project description:Brown algae synthesize various polysaccharides that are ultimately catabolized by marine heterotrophic bacteria. Complex cell wall polysaccharides such as sulfated fucans are considered recalcitrant to microbial degradation and their pathways remain elusive. The branched structure of fucans sterically constraints enzyme-substrate interaction and also, fucan structure varies depending on algae and season challenging adaptation of microbial pathways. Here we show how Lentimonas specialized to overcome the complexity and diversity of sulfated fucans. The strain acquired a 0.9 mbp plasmid with over 200 glycoside hydrolases and sulfatases for the degradation of at least six different sulfated fucans. Per fucan, 100 enzymes are induced and we identified three structural types of fucans with similar pathways depending on their galactose, acetate and sulfate content. The highly decorated structure sulfated fucans expands the copy number and diversity of few key enzyme families, namely GH29, GH95, GH141 and sulfatases S1_15, S1_16 and S1_17. Those enzymes are co-regulated in large operons to step-wise degrade sulfated fucans. Fucose metabolism places additional burden as the conversion of toxic intermediates into lactate and propanediol occurs in a proteome-costly bacterial microcompartment. Through analyzing available genomes and metagenomes, we emphasize that Verrucomicrobia are abundant, yet specialized degraders of complex polysaccharides.
Project description:Synthetic plastics, like polyethylene terephthalate (PET), have become an essential part of modern life. Many of these products are remarkably persistent in the environment, and the accumulation in the environment is recognised as a major threat. Therefore, an increasing interest has been paid to screen for organisms able to degrade and assimilate the plastic. Ideonella sakaiensis was isolated from a plastisphere, a bacterium that solely was thriving on the degradation on PET films. The processes affected by the presence of PET, terephthalic acid, ethylene glycol, ethyl glycolate, and sodium glyoxylate monohydrate was elucidated by differential proteomes. The exposure of PET and its monomers seem to affect two major pathways, the TCA cycle and the β-oxidation pathway, since multiple of the conditions resulted in an increased expression of proteins directly or indirectly involved in these pathways, underlying the importance in the degradation of PET by I. sakaiensis.