Enzymatic polyethylene biorecycling: Confronting challenges and shaping the future

Jin, Jin; Arciszewski, Jane; Auclair, Karine; Jia, Zongchao

doi:10.1016/j.jhazmat.2023.132449

Cited by 21 publications

(12 citation statements)

References 115 publications

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“…Moreover, in addition to genes encoding plastic degrading enzymes, genes related to biofilm formation, bacterial secretion, and cell growth/reproduction would also undergo significant upregulation in a plastic-rich environment. Taken together, these studies underscore the formidable challenge of identifying bona fide protein candidates capable of degrading PE directly . They further highlight the importance of scrutinizing the activity of putative enzymes that can directly act on PE.…”

Section: Discussionmentioning

confidence: 75%

“…The absence of functional groups in PE hampers hydrolysis and other common transformations since its biodegradation would necessitate the introduction of functional groups, often achieved through oxidation. 9 Since the sequences of the PD enzymes clearly suggest a function akin to lipase, esterase, cutinase, or hydrolase and a lack of homology with known oxidase or oxygenase enzymes, which typically catalyze the first modification step in PE prior to chain breakage, 9 it is unlikely that these hydrolases upregulated in the presence of PE possess putative activity toward PE. PE does not contain ester bonds, and its breakdown requires oxidation as a prior step before the yetunclear chain cleavage reaction.…”

Section: ■ Discussionmentioning

confidence: 99%

“…The initial step in PE biodegradation, likely involving the oxidation of inactive C–H bonds, is expected to be the limiting factor due to the high stability of these bonds. The discovery of enzymes that can directly act on PE (PEases) poses a significant challenge, largely attributed to the unclear mechanism of PE enzymatic degradation . Certain secreted enzymes such as manganese peroxidases (MnP), lignin peroxidases (LiP), and laccases have been implicated in the oxidation of waste PE in the environment. − Notably, two enzymes from the waxworm Galleria mellonella have been recombinantly expressed and verified to possess PE oxidization capabilities .…”

Section: Introductionmentioning

confidence: 99%

“…13 However, individually purified or recombinantly expressed direct PE-acting enzymes typically exhibited only limited PE degradation activity. 9 As a result, research on PEases still remains in the discovery stage, predominantly focusing on finding bona f ide direct PE-acting enzymes. Metagenomic studies have proven to be a highly valuable tool for the identification of PETases or PEases, offering promising prospects for sustainable plastic recycling, upcycling, and mitigating plastic pollution.…”

Section: ■ Introductionmentioning

confidence: 99%

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Characterization of Potential Plastic-Degradation Enzymes from Marine Bacteria

Jin,

Jia

2024

ACS Omega

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Polyethylene terephthalate (PET) and polyethylene (PE) are prominent polymer materials that comprise a significant portion of commercial plastic waste. Their durability and slow degradation rate have resulted in significant accumulation of plastic on Earth. In a recent study, macrotranscriptomic profiling of a reconstituted marine bacterial community identified 10 putative enzymes capable of directly acting on PE or PET (PEases or PETases). Among these enzymes, three recombinant proteins were reported to possess PE degradation activity. To select potential plastic degrading enzyme candidates for protein engineering efforts, we expressed and purified eight out of the 10 candidates, excluding two due to poor expression and/or solubility. Notably, several candidate proteins displayed significant esterase activity on p-nitrophenyl butyrate and exhibited unexpected thermostability despite their marine origin. Additionally, we observed dose-and time-dependent hydrolytic activity on the PET trimer substrate. Structural analysis and mutagenesis of a candidate protein confirmed the presence of catalytic triad residues, classifying it as an esterase. Furthermore, we elucidated the structural importance of the two disulfide bonds. Through point mutation experiments, we observed an enhanced hydrolytic activity of a selected enzyme candidate on PET nanoparticles. Our findings challenge the classification of the enzymes directly acting on PE and highlight the significance and complexity of validating PE degradation enzymes identified through metagenomic analysis.

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Section: Discussionmentioning

confidence: 75%

Section: ■ Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Characterization of Potential Plastic-Degradation Enzymes from Marine Bacteria

Jin,

Jia

2024

ACS Omega

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“…These results are in accordance with previous reports that adherence of fungal mycelia to LDPE film is followed by enzyme production and results in surface aberrations and erosion 44 , 45 . Lac, MnP and LiP produced by microbes involved in biodegradation of PE 46 by enhancing the hydrophilicity of PE, allows the microorganisms to attach to PE 45 , 47 and degrade the polymers into small oligomers, dimmers and monomers 40 . Weight loss in LDPE by microalgae due to lignolytic enzymes was reported by 48 .…”

Section: Resultsmentioning

confidence: 99%

Mycodegradation of low-density polyethylene by Cladosporium sphaerospermum, isolated from platisphere

Sathiyabama,

Boomija,

Sathiyamoorthy

et al. 2024

Sci Rep

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Plastic accumulation is a severe threat to the environment due to its resistivity to thermal, mechanical and biological processes. In recent years, microbial degradation of plastic waste disposal is of interest because of its eco-friendly nature. In this study, a total of 33 fungi were isolated from the plastisphere and out of which 28 fungal species showed halo zone of clearance in agarized LDPE media. The fungus showing highest zone of clearance was further used to evaluate its degradation potential. Based on morphological and molecular technique, the fungus was identified as Cladosporium sphaerospermum. The biodegradation of LDPE by C. sphaerospermum was evaluated by various methods. The exposure of LDPE with C. sphaerospermum resulted in weight loss (15.23%) in seven days, higher reduction rate (0.0224/day) and lower half-life (30.93 days). FTIR analysis showed changes in functional group and increased carbonyl index in LDPE treated with C. sphaerospermum. SEMimages evidenced the formation of pits, surface aberrations and grooves on the LDPE film treated with the fungus whereas the untreated control LDPE film showed no change. AFM analysis confirmed the surface changes and roughness in fungus treated LDPE film. This might be due to the extracellular lignolytic enzymes secreted by C. sphaerospermum grown on LDPE. The degradation of polyethylene by Short chain alkanes such as dodecane, hexasiloxane and silane were identified in the extract of fungus incubated with LDPE film through GC–MS analysis which might be due to the degradation of LDPE film by C. sphaerospermum. This was the first report on the LDPE degradation by C. sphaerospermum in very short duration which enables green scavenging of plastic wastes.

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Targeted Genome Mining Facilitates the Discovery of a Promiscuous, Hyperthermostable Amidase from Thermovenabulum Gondwanense with Notable Nylon‐Degrading Capacity

Hoffman,

Rangaswamy,

Cleveland

et al. 2024

Angewandte Chemie

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Plastics are ubiquitous in our ecosystems, and microplastic accumulation in the environment is an emerging global health concern. Since available recycling technologies are not economically competitive with primary plastic production, global use is expected to reach 1231 megatons by 2060, with 493 megatons leeching into the environment each year. To identify new nylon‐recycling biotechnologies, targeted genome mining was used to identify thermostable enzymes capable of degrading polyamides. Here, we describe the characterization of a novel protein sourced from Thermovenabulum gondwanense: TvgC. TvgC is extremely stable, exhibiting a melting temperature of 93 °C and no detectable losses in hydrolytic activity after one week at 60 °C. While nylonases primarily process nylon‐6, TvgC catalysed the degradation of both nylon‐6 and nylon‐6,6 films, which are considerably more difficult to degrade. Finally, conversion experiments demonstrate that TvgC achieves a 1.2 wt% conversion of nylon‐6 film, comparable to that of the most highly engineered nylonases. This novel hyperthermostable protein represents an excellent starting point for future engineering of increasingly efficient nylonases.

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Enzymatic polyethylene biorecycling: Confronting challenges and shaping the future

Cited by 21 publications

References 115 publications

Characterization of Potential Plastic-Degradation Enzymes from Marine Bacteria

Characterization of Potential Plastic-Degradation Enzymes from Marine Bacteria

Mycodegradation of low-density polyethylene by Cladosporium sphaerospermum, isolated from platisphere

Targeted Genome Mining Facilitates the Discovery of a Promiscuous, Hyperthermostable Amidase from Thermovenabulum Gondwanense with Notable Nylon‐Degrading Capacity

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