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.
2020-09-25 | PXD018391 | Pride
Project description:A marine bacterial community that degrades polyethylene
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.
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.
Project description:Poly(ethylene terephthalate) (PET)-degrading bacterium Ideonella sakaiensis produces hydrolytic enzymes that convert PET, via mono(2-hydroxyethyl) terephthalate (MHET), into the monomeric compounds, terephthalic acid (TPA) and ethylene glycol (EG). Understanding PET metabolism is critical if this bacterium is to be engineered for bioremediation and biorecycling. TPA uptake and catabolism in I. sakaiensis have previously been studied, but EG metabolism remains largely unexplored despite its importance. First, we identified two alcohol dehydrogenases (IsPedE and IsPedH) and one aldehyde dehydrogenase (IsPedI) in I. sakaiensis as the homologs of EG metabolic enzymes in Pseudomonas putida KT2440. IsPedE and IsPedH exhibited EG dehydrogenase activities with Ca2+ and a rare earth element (REE) Pr3+, respectively. We further found an upregulated dehydrogenase gene when the bacterium was grown on EG, whose gene product (IsXoxF) displays a minor EG dehydrogenase activity with Pr3+. IsPedE displayed a similar level of activity toward various alcohols. In contrast, IsPedH was more active toward small alcohols, whereas IsXoxF was the opposite. Structural analysis with homology models revealed that IsXoxF had a larger catalytic pocket than IsPedE and IsPedH, which could accommodate relatively bulkier substrates. Pr3+ regulated the protein expression of IsPedE negatively; IsPedH and IsXoxF were positively regulated. Taken together, these results indicated that the combination of IsPedH and IsXoxF complements the function of IsPedE in the presence of REEs. IsPedI exhibited dehydrogenase activity toward various aldehydes with the highest activity toward glycolaldehyde (GAD). This study demonstrated a unique alcohol oxidation pathway of I. sakaiensis, which could be efficient in EG utilization.
Project description:The contamination of marine ecosystems with microplastics, such as the polymer polyethylene, a commonly used component of single-use packaging, is of global concern. Although it has been suggested that biodegradable polymers, such as polylactic acid, may be used to replace some polyethylene packaging, little is known about their effects on marine organisms. Blue mussels, Mytilus edulis, have become a “model organism” for investigating the effects of microplastics in marine ecosystems. We show here that repeated exposure, over a period of 52 days in an outdoor mesocosm setting, of M. edulis to polyethylene microplastics reduced the number of byssal threads produced and the attachment strength (tenacity) by ~50%. Exposure to either type of microplastic altered the haemolymph proteome and, although a conserved response to microplastic exposure was observed, overall polyethylene resulted in more changes to protein abundances than polylactic acid. Many of the proteins affected are involved in vital biological processes, such as immune- and stress- regulation, metabolism and cellular and structural development. Our study highlights the utility of mass spectrometry-based proteomics to assess the health of key marine organisms and identifies the potential mechanisms by which microplastics, both conventional and biodegradable, could affect their ability to form and maintain reefs.
Project description:By screening the secretomes of polymer induced Pseudomonas pseudoalcaligenes we identify a new enzyme PpEst that can degrade the co-aliphatic-aromatic polyester poly(1,4-butylene adipate-co-terephthalate) (PBAT). The discovered enzyme has predicted arylesterase activity and is induced by PBAT added to the growth medium