The metabolic potential of plastics as biotechnological carbon sources – Review and targets for the future

Tiso, Till; Winter, Benedikt; Wei, Ren; Hee, Johann; Witt, Jan de; Wierckx, Nick; Quicker, Peter; Bornscheuer, Uwe T.; Bardow, André; Nogales, Juan; Blank, Lars M.

doi:10.1016/j.ymben.2021.12.006

Cited by 78 publications

(62 citation statements)

References 194 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This problem may be exacerbated by the comparatively low yield of central carbon metabolites obtained from PET monomers, as compared to typical sugar feedstocks or monomers of other plastics. 8 In this context, it is also interesting to point out that Ideonella sakaiensis PET degradation cultures contained low amounts (0.01%) of yeast extract. 26 This may have served precisely the purpose outlined above, namely, to maintain a basal level of cellular metabolism ensuring PETase and MHETase expression.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, improved options for PET recycling or upcycling may translate into less use of crude oil and contribute to the establishment of a circular plastic (bio)economy. [6][7][8][9] The small fraction of PET waste collected for recycling is mostly processed mechanically; however, PET can be recycled mechanically only a few times due to processing-induced chain scission and ensuing degradation of mechanical properties. 10 To circumvent this, chemical recycling (including glycolysis, hydrolysis, methanolysis, and pyrolysis, among others) can be used to depolymerize PET to its constituents TA and EG, followed by synthesis of new virgin PET.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Towards Synthetic PETtrophy: EngineeringPseudomonas putidafor concurrent polyethylene terephthalate (PET) monomer metabolism and PET hydrolase expression

Brandenberg

Schubert

Kruglyak

2022

Preprint

View full text Add to dashboard Cite

BackgroundBiocatalysis offers a promising path for plastic waste management and valorization, especially for hydrolysable plastics such as polyethylene terephthalate (PET). Microbial whole-cell biocatalysts for simultaneous PET degradation and growth on PET monomers would offer a one-step solution toward PET recycling or upcycling. We set out to engineer the industry-proven bacterium Pseudomonas putida for (i) metabolism of PET monomers as sole carbon sources, and (ii) efficient concurrent extracellular expression of PET hydrolases. We pursued this approach for both PET and the related polyester polybutylene adipate co-terephthalate (PBAT), aiming to learn about the determinants and potential applications of bacterial polyester-degrading biocatalysts.ResultsP. putida was engineered to metabolize the PET and PBAT monomer terephthalic acid (TA) through genomic integration of four tphII operon genes from Comamonas sp. E6. Efficient cellular TA uptake was enabled by a point mutation in the native P. putida membrane transporter mhpT. Metabolism of the PET and PBAT monomers ethylene glycol and 1,4-butanediol was achieved through adaptive laboratory evolution. We then used fast design-build-test-learn cycles to engineer extracellular PET hydrolase expression, including tests of (i) the three PET hydrolases LCC, HiC, and IsPETase; (ii) genomic versus plasmid-based expression, using expression plasmids with high, medium, and low cellular copy number; (iii) three different promoter systems; (iv) three membrane anchor proteins for PET hydrolase cell surface display; and (v) a 30-mer signal peptide library for PET hydrolase secretion. PET hydrolase surface display and secretion was successfully engineered but often resulted in host cell fitness costs, which could be mitigated by promoter choice and altering construct copy number. Plastic biodegradation assays with the best PET hydrolase expression constructs genomically integrated into our monomer-metabolizing P. putida strains resulted in various degrees of plastic depolymerization, although self-sustaining bacterial growth remained elusive.ConclusionOur results show that balancing extracellular PET hydrolase expression with cellular fitness under nutrient-limiting conditions is a challenge. The precise knowledge of such bottlenecks, together with the vast array of PET hydrolase expression tools generated and tested here, may serve as a baseline for future efforts to engineer P. putida or other bacterial hosts towards becoming efficient whole-cell polyester-degrading biocatalysts.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Towards Synthetic PETtrophy: EngineeringPseudomonas putidafor concurrent polyethylene terephthalate (PET) monomer metabolism and PET hydrolase expression

Brandenberg

Schubert

Kruglyak

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…The monomers can also be upcycled toward more valuable compounds. As discussed in the bowtie model by Tiso et al (2021) , bacterial metabolism can be adapted to convert plastic imputes (monomers, oligomers) into a wide variety of compounds such as aromatics, organic alcohols and more. The promise of this has already been shown by the conversion of terephthalic acid to vanillin, coumarin and catechol ( Kim et al, 2019 ; Sadler and Wallace, 2021 ).…”

Section: The Future Of Plastic Depolymerization—biorecycling and Bio-...mentioning

confidence: 99%

“…The promise of this has already been shown by the conversion of terephthalic acid to vanillin, coumarin and catechol ( Kim et al, 2019 ; Sadler and Wallace, 2021 ). The review of Tiso et al (2021) discusses the promise of engineered microorganisms for the processing of these plastics and the promise of plastic monomers as substitutes for current petrochemical-based materials extensively. The adjustments of these metabolic pathways were extensively described showing the possibilities to further engineer these pathways allowing for microbial upcycling of plastics ( Tiso et al, 2021 ).…”

Section: The Future Of Plastic Depolymerization—biorecycling and Bio-...mentioning

confidence: 99%

Toward Microbial Recycling and Upcycling of Plastics: Prospects and Challenges

2022

View full text Add to dashboard Cite

Annually, 400 Mt of plastics are produced of which roughly 40% is discarded within a year. Current plastic waste management approaches focus on applying physical, thermal, and chemical treatments of plastic polymers. However, these methods have severe limitations leading to the loss of valuable materials and resources. Another major drawback is the rapid accumulation of plastics into the environment causing one of the biggest environmental threats of the twenty-first century. Therefore, to complement current plastic management approaches novel routes toward plastic degradation and upcycling need to be developed. Enzymatic degradation and conversion of plastics present a promising approach toward sustainable recycling of plastics and plastics building blocks. However, the quest for novel enzymes that efficiently operate in cost-effective, large-scale plastics degradation poses many challenges. To date, a wide range of experimental set-ups has been reported, in many cases lacking a detailed investigation of microbial species exhibiting plastics degrading properties as well as of their corresponding plastics degrading enzymes. The apparent lack of consistent approaches compromises the necessary discovery of a wide range of novel enzymes. In this review, we discuss prospects and possibilities for efficient enzymatic degradation, recycling, and upcycling of plastics, in correlation with their wide diversity and broad utilization. Current methods for the identification and optimization of plastics degrading enzymes are compared and discussed. We present a framework for a standardized workflow, allowing transparent discovery and optimization of novel enzymes for efficient and sustainable plastics degradation in the future.

show abstract

“…Selected throughout insects and microbes’ evolution, these associations may teach many lessons on how to find efficient microbial degraders and detoxifiers of plant tissues, how to assemble an efficient plant-degrading community, and how to promote metabolic interactions for obtaining nutrients from recalcitrant polymers. Investigating the microbial strategies for decaying plant biomass could bioinspire the tuned application of hydrolytic and oxidative pathways to degrade plastics and to generate value-added products ( Holladay et al, 2007 ; Cook and Doran-Peterson, 2010 ; Huang et al, 2010 ; Sun and Scharf, 2010 ; Shi et al, 2011 ; Koch et al, 2014 ; Wang et al, 2015 ; Dangles and Casas, 2019 ; Tiso et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Lessons From Insect Fungiculture: From Microbial Ecology to Plastics Degradation

Barcoto

Rodrigues

2022

Front. Microbiol.

View full text Add to dashboard Cite

Anthropogenic activities have extensively transformed the biosphere by extracting and disposing of resources, crossing boundaries of planetary threat while causing a global crisis of waste overload. Despite fundamental differences regarding structure and recalcitrance, lignocellulose and plastic polymers share physical-chemical properties to some extent, that include carbon skeletons with similar chemical bonds, hydrophobic properties, amorphous and crystalline regions. Microbial strategies for metabolizing recalcitrant polymers have been selected and optimized through evolution, thus understanding natural processes for lignocellulose modification could aid the challenge of dealing with the recalcitrant human-made polymers spread worldwide. We propose to look for inspiration in the charismatic fungal-growing insects to understand multipartite degradation of plant polymers. Independently evolved in diverse insect lineages, fungiculture embraces passive or active fungal cultivation for food, protection, and structural purposes. We consider there is much to learn from these symbioses, in special from the community-level degradation of recalcitrant biomass and defensive metabolites. Microbial plant-degrading systems at the core of insect fungicultures could be promising candidates for degrading synthetic plastics. Here, we first compare the degradation of lignocellulose and plastic polymers, with emphasis in the overlapping microbial players and enzymatic activities between these processes. Second, we review the literature on diverse insect fungiculture systems, focusing on features that, while supporting insects’ ecology and evolution, could also be applied in biotechnological processes. Third, taking lessons from these microbial communities, we suggest multidisciplinary strategies to identify microbial degraders, degrading enzymes and pathways, as well as microbial interactions and interdependencies. Spanning from multiomics to spectroscopy, microscopy, stable isotopes probing, enrichment microcosmos, and synthetic communities, these strategies would allow for a systemic understanding of the fungiculture ecology, driving to application possibilities. Detailing how the metabolic landscape is entangled to achieve ecological success could inspire sustainable efforts for mitigating the current environmental crisis.

show abstract

The metabolic potential of plastics as biotechnological carbon sources – Review and targets for the future

Cited by 78 publications

References 194 publications

Towards Synthetic PETtrophy: EngineeringPseudomonas putidafor concurrent polyethylene terephthalate (PET) monomer metabolism and PET hydrolase expression

Towards Synthetic PETtrophy: EngineeringPseudomonas putidafor concurrent polyethylene terephthalate (PET) monomer metabolism and PET hydrolase expression

Toward Microbial Recycling and Upcycling of Plastics: Prospects and Challenges

Lessons From Insect Fungiculture: From Microbial Ecology to Plastics Degradation

Contact Info

Product

Resources

About