scholarly journals Characterization and engineering of a two-enzyme system for plastics depolymerization

2020 ◽  
Vol 117 (41) ◽  
pp. 25476-25485 ◽  
Author(s):  
Brandon C. Knott ◽  
Erika Erickson ◽  
Mark D. Allen ◽  
Japheth E. Gado ◽  
Rosie Graham ◽  
...  
Keyword(s):  
Enzyme System ◽  
Environmental Crisis ◽  
Chimeric Proteins ◽  
Serine Hydrolase ◽  
Core Domain ◽  
Global Environmental ◽  
Pet Film ◽  
Lid Domain ◽  
Hydrolysis Of ◽  
Synergistic Relationship

Plastics pollution represents a global environmental crisis. In response, microbes are evolving the capacity to utilize synthetic polymers as carbon and energy sources. Recently,Ideonella sakaiensiswas reported to secrete a two-enzyme system to deconstruct polyethylene terephthalate (PET) to its constituent monomers. Specifically, theI. sakaiensisPETase depolymerizes PET, liberating soluble products, including mono(2-hydroxyethyl) terephthalate (MHET), which is cleaved to terephthalic acid and ethylene glycol by MHETase. Here, we report a 1.6 Å resolution MHETase structure, illustrating that the MHETase core domain is similar to PETase, capped by a lid domain. Simulations of the catalytic itinerary predict that MHETase follows the canonical two-step serine hydrolase mechanism. Bioinformatics analysis suggests that MHETase evolved from ferulic acid esterases, and two homologous enzymes are shown to exhibit MHET turnover. Analysis of the two homologous enzymes and the MHETase S131G mutant demonstrates the importance of this residue for accommodation of MHET in the active site. We also demonstrate that the MHETase lid is crucial for hydrolysis of MHET and, furthermore, that MHETase does not turnover mono(2-hydroxyethyl)-furanoate or mono(2-hydroxyethyl)-isophthalate. A highly synergistic relationship between PETase and MHETase was observed for the conversion of amorphous PET film to monomers across all nonzero MHETase concentrations tested. Finally, we compare the performance of MHETase:PETase chimeric proteins of varying linker lengths, which all exhibit improved PET and MHET turnover relative to the free enzymes. Together, these results offer insights into the two-enzyme PET depolymerization system and will inform future efforts in the biological deconstruction and upcycling of mixed plastics.

scholarly journals Coastal wetlands can be saved from sea level rise by recreating past tidal regimes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mahmood Sadat-Noori ◽  
Caleb Rankin ◽  
Duncan Rayner ◽  
Valentin Heimhuber ◽  
Troy Gaston ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Wetlands ◽  
Environmental Crisis ◽  
Ground Vegetation ◽  
Proof Of Concept ◽  
Tidal Regime ◽  
Vegetation Sampling ◽  
Global Environmental ◽  
Intertidal Ecosystems

AbstractClimate change driven Sea Level Rise (SLR) is creating a major global environmental crisis in coastal ecosystems, however, limited practical solutions are provided to prevent or mitigate the impacts. Here, we propose a novel eco-engineering solution to protect highly valued vegetated intertidal ecosystems. The new ‘Tidal Replicate Method’ involves the creation of a synthetic tidal regime that mimics the desired hydroperiod for intertidal wetlands. This synthetic tidal regime can then be applied via automated tidal control systems, “SmartGates”, at suitable locations. As a proof of concept study, this method was applied at an intertidal wetland with the aim of restabilising saltmarsh vegetation at a location representative of SLR. Results from aerial drone surveys and on-ground vegetation sampling indicated that the Tidal Replicate Method effectively established saltmarsh onsite over a 3-year period of post-restoration, showing the method is able to protect endangered intertidal ecosystems from submersion. If applied globally, this method can protect high value coastal wetlands with similar environmental settings, including over 1,184,000 ha of Ramsar coastal wetlands. This equates to a saving of US$230 billion in ecosystem services per year. This solution can play an important role in the global effort to conserve coastal wetlands under accelerating SLR.

Enzyme system of Clostridium stercorarium for hydrolysis of arabinoxylan: reconstitution of the in vivo system from recombinant enzymes

Microbiology ◽  
2004 ◽  
Vol 150 (7) ◽  
pp. 2257-2266 ◽  
Author(s):  
Helmuth Adelsberger ◽  
Christian Hertel ◽  
Erich Glawischnig ◽  
Vladimir V. Zverlov ◽  
Wolfgang H. Schwarz
Keyword(s):  
Extracellular Enzymes ◽  
Enzyme System ◽  
Thermophilic Bacterium ◽  
Recombinant Enzymes ◽  
Type Mode ◽  
Complete Set ◽  
First Time ◽  
Hydrolysis Of

Four extracellular enzymes of the thermophilic bacterium Clostridium stercorarium are involved in the depolymerization of de-esterified arabinoxylan: Xyn11A, Xyn10C, Bxl3B, and Arf51B. They were identified in a collection of eight clones producing enzymes hydrolysing xylan (xynA, xynB, xynC), β-xyloside (bxlA, bxlB, bglZ) and α-arabinofuranoside (arfA, arfB). The modular enzymes Xyn11A and Xyn10C represent the major xylanases in the culture supernatant of C. stercorarium. Both hydrolyse arabinoxylan in an endo-type mode, but differ in the pattern of the oligosaccharides produced. Of the glycosidases, Bxl3B degrades xylobiose and xylooligosaccharides to xylose, and Arf51B is able to release arabinose residues from de-esterified arabinoxylan and from the oligosaccharides generated. The other glycosidases either did not attack or only marginally attacked these oligosaccharides. Significantly more xylanase and xylosidase activity was produced during growth on xylose and xylan. This is believed to be the first time that, in a single thermophilic micro-organism, the complete set of enzymes (as well as the respective genes) to completely hydrolyse de-esterified arabinoxylan to its monomeric sugar constituents, xylose and arabinose, has been identified and the enzymes produced in vivo. The active enzyme system was reconstituted in vitro from recombinant enzymes.

scholarly journals Optimization of a minimal synergistic enzyme system for hydrolysis of raw cassava pulp

RSC Advances ◽  
2017 ◽  
Vol 7 (76) ◽  
pp. 48444-48453 ◽  
Author(s):  
Benjarat Bunterngsook ◽  
Thanaporn Laothanachareon ◽  
Suda Natrchalayuth ◽  
Sirithorn Lertphanich ◽  
Tatsuya Fujii ◽  
...  
Keyword(s):  
Cell Wall ◽  
Enzyme System ◽  
Starch Granules ◽  
Cell Wall Polysaccharides ◽  
Cassava Pulp ◽  
Lignocellulosic Wastes ◽  
Hydrolysis Of

Cassava pulp is an underused agricultural by-product comprising residual starch granules entrapped in cell wall polysaccharides, making it unique from other lignocellulosic wastes in terms of enzymatic processing.

β-Glucosidase: microbial production and effect on enzymatic hydrolysis of cellulose

1977 ◽  
Vol 23 (2) ◽  
pp. 139-147 ◽  
Author(s):  
D. Sternberg ◽  
P. Vuayakumar ◽  
E. T. Reese
Keyword(s):  
Enzymatic Hydrolysis ◽  
Liquid Culture ◽  
Enzyme System ◽  
Microbial Production ◽  
Enzymatic Conversion ◽  
Enzymatic Hydrolysis Of Cellulose ◽  
Black Aspergilli ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of ◽  
Predominant Product

The enzymatic conversion of cellulose is catalyzed by a multiple enzyme system. The Trichoderma enzyme system has been studied extensively and has insufficient β-glucosidase (EC 3.2.1.21) activity for the practical saccharification of cellulose. The black aspergilli (A. niger and A. phoenicis) were superior producers of β-glucosidase and a method for production of this enzyme in liquid culture is presented. When Trichoderma cellulase preparations are supplemented with β-glucosidase from Aspergillus during practical saccharifications, glucose is the predominant product and the rate of saccharification is significantly increased. The stimulatory effect of β-glucosidase appears to be due to the removal of inhibitory levels of cellobiose.

The Convention on Biological Diversity: From Realism to Cosmopolitanism

2005 ◽  
Vol 31 ◽  
pp. 335-362 ◽  
Author(s):  
Virginie Maris
Keyword(s):  
Deleterious Effect ◽  
Biological Diversity ◽  
Global Scale ◽  
Environmental Crisis ◽  
Convention On Biological Diversity ◽  
International Agreement ◽  
Local Populations ◽  
Conservation Measures ◽  
Global Environmental

The decline of biodiversity is without a doubt one of the most important symptoms of what could be called a “global environmental crisis.” Our ability to stop this decline depends on the capacity to implement an effective, collective system of preservation on a global scale. In this paper, I will analyze the Convention on Biological Diversity (CBD), the international agreement that aims at creating this type of global cooperation.While I consider that cosmopolitan governance is desirable, given the legitimacy of the preservation of global biological diversity, I will not attempt to directly argue for it here. Still, it is worth mentioning some of the reasons that might lead us to adopt this position. First, certain past conservation measures have been harshly criticized as imperialistic. For example, Project Tiger in India, which Western environmentalists often cited as a success, have had a deleterious effect on local populations.

The Business of More

2016 ◽  
Author(s):  
Peter Dauvergne
Keyword(s):  
Economic Growth ◽  
Multinational Corporations ◽  
Environmental Crisis ◽  
Ecological Footprints ◽  
Global Sustainability ◽  
Global Environmental ◽  
The Pacific ◽  
Production And Consumption ◽  
Big Box ◽  
Wasteful Consumption

This chapter pans out from the islands of the Pacific to analyze the forces of unsustainable production and consumption underlying the global sustainability crisis. It demonstrates how, everywhere, inequality is increasing, as is conspicuous, wasteful consumption as companies pursue more sales and more profits. The chapter highlights how advertisers manufacture desires and needs, how big-box retailers and brand manufacturers claiming to be responsible and sustainable are selling inexpensive, nondurable products, and how governments finance infrastructure (e.g., subsidizing roads and bridges) to stimulate even higher levels of consumption. States pursue more consumption in the name of economic growth; multinational corporations for more profits for owners and shareholders; and the world’s billionaires to amass even more wealth. One result, as this chapter documents, is extreme and rising inequality, with 1 percent of the world’s population now controlling approximately half of the world’s wealth. Other results include rising ecological footprints, overexploitation of natural resources, and an escalating global environmental crisis – the themes of the book’s next chapter.

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