scholarly journals Fungal Enzymes as Catalytic Tools for Polyethylene Terephthalate (PET) Degradation

2021 ◽  
Vol 7 (11) ◽  
pp. 931
Author(s):  
Seyedehazita Ahmaditabatabaei ◽  
Godfrey Kyazze ◽  
Hafiz M. N. Iqbal ◽  
Tajalli Keshavarz
Keyword(s):  
Polyethylene Terephthalate ◽  
Catalytic Mechanism ◽  
Environmental Fate ◽  
Plastic Waste ◽  
Environmental Crisis ◽  
Environmental Matrices ◽  
Plastic Pollution ◽  
Fungal Enzymes ◽  
Bacterial Enzyme ◽  
Human Health Effects

The ubiquitous persistence of plastic waste in diverse forms and different environmental matrices is one of the main challenges that modern societies are facing at present. The exponential utilization and recalcitrance of synthetic plastics, including polyethylene terephthalate (PET), results in their extensive accumulation, which is a significant threat to the ecosystem. The growing amount of plastic waste ending up in landfills and oceans is alarming due to its possible adverse effects on biota. Thus, there is an urgent need to mitigate plastic waste to tackle the environmental crisis of plastic pollution. With regards to PET, there is a plethora of literature on the transportation route, ingestion, environmental fate, amount, and the adverse ecological and human health effects. Several studies have described the deployment of various microbial enzymes with much focus on bacterial-enzyme mediated removal and remediation of PET. However, there is a lack of consolidated studies on the exploitation of fungal enzymes for PET degradation. Herein, an effort has been made to cover this literature gap by spotlighting the fungi and their unique enzymes, e.g., esterases, lipases, and cutinases. These fungal enzymes have emerged as candidates for the development of biocatalytic PET degradation processes. The first half of this review is focused on fungal biocatalysts involved in the degradation of PET. The latter half explains three main aspects: (1) catalytic mechanism of PET hydrolysis in the presence of cutinases as a model fungal enzyme, (2) limitations hindering enzymatic PET biodegradation, and (3) strategies for enhancement of enzymatic PET biodegradation.

scholarly journals Development of XU Plastic Shredder for Cost Effective Means of Minimizing Polyethylene Terephthalate Plastic Waste Volume

2019 ◽  
Vol 8 (12) ◽  
pp. 2821-2825
Keyword(s):  
Polyethylene Terephthalate ◽  
Effective Means ◽  
Transportation Cost ◽  
Cost Effective ◽  
Plastic Waste ◽  
Volume Reduction ◽  
Plastic Pollution ◽  
Dump Site ◽  
Plastic Materials ◽  
The Cost

This study deals with the development of a polyethylene terephthalate or PET plastic shredder for Xavier University in order to reduce the transportation cost of used plastic bottles to the designated dump site some 9 kilometers uphill. The development of this 2 horsepower plastic shredder is also useful for the reduction of the volume of plastic materials in the Material Recovery Facility of the municipality of Alubijid, Misamis Oriental. Xavier University has a collection of used plastic bottles of around 365 kg per month with an aggregate volume of 17.42 m3 and until the next garbage collection services arrive, the amount of plastic waste will occupy a considerable volume or space. This study focuses on the development and testing of the capacity of the developed plastic shredder. This study is inspired by the project of Mr. Dave Hakkens, called Precious Plastic, that aims to fight plastic pollution by developing machines that aid in recycling all sorts of plastic materials. The objective of this study is to analyze the cost of developing these machines in the Xavier University setting, their cost of operation, and effectiveness through minimizing the volume of plastic bottle. In this study, only polyethylene terephthalate (PET) plastic are being used. By consultation of local manufacturing firms in developing the machines through their specialized equipment, the authors have found that cost of development is high. However, a compromise between quality and precision has been decided to reduce the overall cost of the development of the machine. The authors were able to develop the proposed machines through the application of skills in machine workshop practices in the mechanical engineering laboratory. The XU plastic shredder has an average plastic volume reduction of 82.41%. With this volume reduction, the number of trips for the garbage truck collector is also reduced by 82.41% thereby saving delivery cost and manpower requirements. The cost of power consumption of the XU Plastic Shredder is only PhP36.52 per hour.

scholarly journals Beverage bottle capacity, packaging efficiency, and the potential for plastic waste reduction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Becerril-Arreola ◽  
R. E. Bucklin
Keyword(s):  
Product Category ◽  
Plastic Waste ◽  
Waste Reduction ◽  
Plastic Pollution ◽  
Local Data ◽  
Pet Waste ◽  
Pet Bottles ◽  
Enormous Amount ◽  
Packaging Efficiency ◽  
The U.S

AbstractPlastic pollution is a pressing issue because authorities struggle to contain and process the enormous amount of waste produced. We study the potential for reducing plastic waste by examining the efficiency with which different polyethylene terephthalate (PET) bottles deliver beverages. We find that 80% of the variation in bottle weight is explained by bottle capacity, 16% by product category, and 1% by brand. Bottle weight is quadratic and convex function of capacity, which implies that medium capacity bottles are most efficient at delivering consumable product. Local data on PET bottle sales and municipal waste recovery validate the findings. A 20% shift in consumption from smaller to larger bottles could reduce the production of PET waste by over 10,000 t annually in the U.S. alone.

Structural insights into dihydroxylation of terephthalate, a product of polyethylene terephthalate degradation

2022 ◽  
Author(s):  
Jai Krishna Mahto ◽  
Neetu Neetu ◽  
Monica Sharma ◽  
Monika Dubey ◽  
Bhanu Prakash Vellanki ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Substrate Specificity ◽  
Polyethylene Terephthalate ◽  
Active Site ◽  
Catalytic Domain ◽  
Structural Features ◽  
Comamonas Testosteroni ◽  
Plastic Pollution ◽  
Microbial Utilization ◽  
Steady State Kinetics

Biodegradation of terephthalate (TPA) is a highly desired catabolic process for the bacterial utilization of this Polyethylene terephthalate (PET) depolymerization product, but to date, the structure of terephthalate dioxygenase (TPDO), a Rieske oxygenase (RO) that catalyzes the dihydroxylation of TPA to a cis -diol is unavailable. In this study, we characterized the steady-state kinetics and first crystal structure of TPDO from Comamonas testosteroni KF1 (TPDO KF1 ). The TPDO KF1 exhibited the substrate specificity for TPA ( k cat / K m = 57 ± 9 mM −1 s −1 ). The TPDO KF1 structure harbors characteristics RO features as well as a unique catalytic domain that rationalizes the enzyme’s function. The docking and mutagenesis studies reveal that its substrate specificity to TPA is mediated by Arg309 and Arg390 residues, two residues positioned on opposite faces of the active site. Additionally, residue Gln300 is also proven to be crucial for the activity, its substitution to alanine decreases the activity ( k cat ) by 80%. Together, this study delineates the structural features that dictate the substrate recognition and specificity of TPDO. Importance The global plastic pollution has become the most pressing environmental issue. Recent studies on enzymes depolymerizing polyethylene terephthalate plastic into terephthalate (TPA) show some potential in tackling this. Microbial utilization of this released product, TPA is an emerging and promising strategy for waste-to-value creation. Research from the last decade has discovered terephthalate dioxygenase (TPDO), as being responsible for initiating the enzymatic degradation of TPA in a few Gram-negative and Gram-positive bacteria. Here, we have determined the crystal structure of TPDO from Comamonas testosteroni KF1 and revealed that it possesses a unique catalytic domain featuring two basic residues in the active site to recognize TPA. Biochemical and mutagenesis studies demonstrated the crucial residues responsible for the substrate specificity of this enzyme.

scholarly journals Clean Enzymatic depolymerization of highly crystalline polyethylene terephthalate in moist-solid reaction mixtures

2020 ◽  
Author(s):  
Sandra Kaabel ◽  
J. P. Daniel Therien ◽  
Catherine E. Deschênes ◽  
Dustin Duncan ◽  
Tomislav Friščić ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Metal Organic Framework ◽  
Direct Synthesis ◽  
Plastic Pollution ◽  
Solid Reaction ◽  
Pollution Problem ◽  
Metal Organic ◽  
Dilute Aqueous Solutions ◽  
Space Time Yield ◽  
Crystalline Forms

AbstractLess than 9% of the plastic produced is recycled after use, contributing to the global plastic pollution problem. While polyethylene terephthalate (PET) is one of the most common plastics, its thermomechanical recycling generates a material of lesser quality. Enzymes are highly selective, renewable catalysts active at mild temperatures; however, the current consensus is that they lack activity towards the more crystalline forms of PET. We report here that when used in moist-solid reaction mixtures instead of the typical dilute aqueous solutions, enzymes can directly depolymerize high crystallinity PET in 13-fold higher space-time yield and a 15-fold higher enzyme efficiency than prior reports. Further, this process shows a 26-fold selectivity for terephthalic acid over other hydrolysis products, which allows the direct synthesis of UiO-66 metal-organic framework.

scholarly journals Current Advances in the Biodegradation and Bioconversion of Polyethylene Terephthalate

2021 ◽  
Vol 10 (1) ◽  
pp. 39
Author(s):  
Xinhua Qi ◽  
Wenlong Yan ◽  
Zhibei Cao ◽  
Mingzhu Ding ◽  
Yingjin Yuan
Keyword(s):  
Polyethylene Terephthalate ◽  
Microbial Consortium ◽  
Tricarboxylic Acid Cycle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Microbial Consortia ◽  
Plastic Pollution ◽  
One Step ◽  
Complex Polymers ◽  
The One

Polyethylene terephthalate (PET) is a widely used plastic that is polymerized by terephthalic acid (TPA) and ethylene glycol (EG). In recent years, PET biodegradation and bioconversion have become important in solving environmental plastic pollution. More and more PET hydrolases have been discovered and modified, which mainly act on and degrade the ester bond of PET. The monomers, TPA and EG, can be further utilized by microorganisms, entering the tricarboxylic acid cycle (TCA cycle) or being converted into high value chemicals, and finally realizing the biodegradation and bioconversion of PET. Based on synthetic biology and metabolic engineering strategies, this review summarizes the current advances in the modified PET hydrolases, engineered microbial chassis in degrading PET, bioconversion pathways of PET monomers, and artificial microbial consortia in PET biodegradation and bioconversion. Artificial microbial consortium provides novel ideas for the biodegradation and bioconversion of PET or other complex polymers. It is helpful to realize the one-step bioconversion of PET into high value chemicals.

scholarly journals How important risk analysis of plastic pollution in coastal area? Case study in Masohi, Central Maluku

2020 ◽  
Vol 200 ◽  
pp. 02014
Author(s):  
Bachtiar W Mutaqin ◽  
Muh Aris Marfai ◽  
Muhammad Helmi ◽  
Nurhadi Nurhadi ◽  
Muhammad Rizali Umarella ◽  
...  
Keyword(s):  
Public Awareness ◽  
Coastal Areas ◽  
Plastic Waste ◽  
Small Island ◽  
Marine Biota ◽  
Plastic Pollution ◽  
Short Period ◽  
Almost All ◽  
And Function ◽  
Interdisciplinary Study

Human pressure on the coastal and aquatic surrounding ecosystem in Indonesia, through plastic waste, is increasing, considering that 60 % of the approximately 250 million people live in the coastal areas. Plastic waste originating from human activities has become a massive problem in almost all the small island and coastal regions, especially in the eastern part of Indonesia. This condition is caused by poor waste management and a lack of public awareness in disposing of waste in its place, including in an area known as its marine biodiversities and marine tourism spots like Masohi in Central Maluku. Also, the composition of waste is dominated by plastic waste that cannot be decomposed in a short period, continue circulated on the ocean currents, and will be deposited in coastal areas. Furthermore, some plastic waste will break down into micro-plastics that pollute not only the environment but also marine biota, which are often consumed by humans. This situation profoundly affects the sustainability and function of aquaecosystem services in coastal areas. Therefore, a comprehensive policy and regulation, and interdisciplinary study for analysing vulnerable coastal ecosystem, and mitigating the potential risk of plastic pollution in Masohi, Central Maluku are essential to be conducted.

scholarly journals Pendidikan Lingkungan: Plastic Pollution Awareness di Desa Jatireja, Cikarang, Jawa Barat

2020 ◽  
Vol 1 (2) ◽  
pp. 88 ◽  
Author(s):  
Filson M Sidjabat ◽  
Yunita Ismail ◽  
Evi Rismauli
Keyword(s):  
Environmental Education ◽  
Behavioral Change ◽  
Waste Treatment ◽  
Waste Utilization ◽  
Plastic Waste ◽  
Plastic Pollution ◽  
West Java ◽  
Education Community ◽  
The Government ◽  
Social Empowerment

Waste problems in Indonesia has reached a critical point that is contaminating many aspects in community. Poor waste management in land have an impact in water pollutions, rivers, and toward the ocean. This rivers and oceans pollution are become the spotlights for the world and the government. As a part of education community in West Java, President University has an important role to educati and find solutions relate with this issues, one of them is to implement Thidharma in the form of social empowerment in Jatireja Village. This environmental education activities was sharing knowledge about plastic waste treatment and management that can be conducted in household scale, and to encourage behavioral change and awareness among communities. Creative product of eco-brick was also implemented tas a part of waste utilization to make valueable product. Environmental education are needed to improve community awareness on plastic waste in Indonesia, especially in West Java.

Identifying global hotspots of plastic waste accumulation along river networks

2021 ◽  
Author(s):  
Jesus Gomez-Velez ◽  
Stefan Krause
Keyword(s):  
Multiple Scales ◽  
Transport Model ◽  
Freshwater Ecosystems ◽  
River Network ◽  
Plastic Waste ◽  
Trapping Efficiency ◽  
River Networks ◽  
Clear Understanding ◽  
Relative Location ◽  
Plastic Pollution

<p>Global plastic pollution is affecting ecosystems and human health globally. Proposing solutions and coping strategies for this threat requires a clear understanding of the processes controlling the fate and transport of mismanaged plastics at multiple scales, going from watersheds to regions and even continents. River corridors are the primary conveyor and trap for mismanaged plastic produced within the landscape and eventually released to the ocean. New approaches that apply technological sensing innovations for monitoring plastic waste in aquatic environments can improve observations and plastic waste datasets globally. However, our understanding of when, where, and how to target monitoring is limited, reducing the benefit gained. There is therefore a critical demand for predictions of hotspots (as well as hot moments) of plastic accumulation along river networks globally, in order to optimize observational capacity.     </p><p>Here, we present a new global flow and transport model for plastic waste in riverine environments. Our model predicts that only a small fraction (roughly 2.5%) of the global mismanaged plastic that entered rivers since the 1950s has been delivered to the ocean by 2020, with an overwhelming majority sequestered in freshwater ecosystems. Furthermore, we predict the patterns of mismanaged plastic accumulation and its residence time depend on (i) the topology and geometry of the river network, (ii) the relative location of plastic sources, and (ii) the relative location and trapping efficiency of flow regulation structures, primarily large dams. Our results highlight the role of rivers as major sinks for plastic waste and the need for targeted remedial strategies that consider the structure of the river network and anthropogenic regulation when proposing intervention measures and sampling efforts.</p>

scholarly journals Pyro-Oil and Wax Recovery from Reclaimed Plastic Waste in a Continuous Auger Pyrolysis Reactor

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2040 ◽  
Author(s):  
Sultan Majed Al-Salem ◽  
Yang Yang ◽  
Jiawei Wang ◽  
Gary Anthony Leeke
Keyword(s):  
Product Distribution ◽  
Plastic Waste ◽  
Densification Process ◽  
Plastic Pollution ◽  
Waste Plastic ◽  
Diesel Fuels ◽  
Plastic Recycling ◽  
Plastic Wastes ◽  
Liquid Products ◽  
Pyrolysis Reactor

The increasing global waste plastic pollution is urging people to take immediate actions on effective plastic recycling and processing. In this work, we report the results of processing reclaimed plastic wastes from unsanitary landfill site in Kuwait by using a bench scale continuous auger pyrolysis system. The plastic feedstock was characterised. After a simple thermal densification process, the material was fed to the pyrolysis system at 500 °C. The pyro-oil and wax products were collected and characterised. The process mass balance was developed on dry basis, and the yields of pyro-oil, light wax, heavy wax and gases were 5.5, 23.8, 69.4 and 1.3 wt%, respectively. The findings have indicated that the reclamation of plastic waste from landfill was feasible in terms of the product distribution and characteristics. Further liquid analysis confirmed that the liquid products contained fractions that are comparable to petrol and diesel fuels. The wax products are viable and have potential application as coating, covering and lubrication.

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