An engineered artificial consortium for polyethylene terephthalate (PET) biodegradation composed of two metabolically engineered Bacillus subtilis 168 strains that secrete PETase and MHETase, plus Rhodococcus jostii RHA1 and Pseudomonas putida KT2440. The design partitions PET depolymerization, terephthalic acid utilization, and ethylene glycol utilization across different members to reduce product inhibition during PET degradation.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Bacillus subtilis 168 Bs_PETase — ontology label: Bacillus subtilis | NCBITaxon:1423 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
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N/A |
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| Bacillus subtilis 168 Bs_MHETase — ontology label: Bacillus subtilis | NCBITaxon:1423 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
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N/A |
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| Rhodococcus jostii RHA1 | NCBITaxon:101510 · TaxonMech · TraitMech |
SECONDARY_FERMENTER
CROSS_FEEDER
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N/A |
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| Pseudomonas putida KT2440 | NCBITaxon:160488 · TaxonMech · TraitMech |
SECONDARY_FERMENTER
CROSS_FEEDER
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N/A |
|
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Ecological Interactions
The graph shows only explicitly linked interaction participants. Community members without an asserted participant link are omitted; membership alone does not imply an interaction.
PETase-MHETase Depolymerization Module
Two engineered B. subtilis strains secrete complementary extracellular PETase and MHETase, converting PET through MHET to TPA and EG. The paired module degrades BHET faster than Bs_PETase alone, and the two-member consortium degraded 13.6% of PET film after 7 days in LB. This enzyme division of labor does not establish nutrient uptake by the MHETase-producing Bacillus itself.
Source Taxon: Bacillus subtilis 168 Bs_PETase
Target Taxon: Bacillus subtilis 168 Bs_MHETase
Metabolites: poly(ethylene terephthalate) macromolecule (CHEBI:53259 · MediaIngredientMech · CMMMech)
MHETase releases terephthalic acid from MHET, creating the inhibitory PET hydrolysis product consumed by Rhodococcus jostii RHA1.
MHETase also releases ethylene glycol from MHET, creating the inhibitory PET hydrolysis product consumed by Pseudomonas putida KT2440.
Evidence
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PMID:35003008 - SUPPORT (IN_VITRO)"PET is degraded into MHET catalyzed by PETase"
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PMID:35003008 - SUPPORT (IN_VITRO)"MHET is degraded into TPA and EG catalyzed by MHETase"
Rhodococcus TPA Detoxification Module
CROSS_FEEDINGR. jostii RHA1 completely degraded 2 g/L TPA within 28 h in the standalone assay. Exogenous TPA inhibited degradation and bacterial growth; adding RHA1 lowered TPA during BHET hydrolysis and improved three-member PET-film weight loss to 31.2% after 7 days in Results, not the 3 days stated in the abstract. These assays support product-inhibition relief, without directly isolating enzyme secretion as its only mediator.
Source Taxon: Bacillus subtilis 168 Bs_MHETase
Target Taxon: Rhodococcus jostii RHA1
Metabolites: terephthalic acid (CHEBI:15702 · MediaIngredientMech · CMMMech)
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
PARTIAL - RHA1 utilization removes inhibitory TPA produced by the Bacillus module, supporting the four-member degradation design. Standalone consumption, exogenous-product inhibition and consortium comparisons support this mechanism, but do not isolate its quantitative contribution to the optimized Wn-film endpoint or directly measure enzyme-secretion mediation.
Evidence
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PMID:35003008 - SUPPORT (IN_VITRO)"R. jostii RHA1 was verified to degrade TPA efficiently, with 2 g/L TPA being completely degraded within 28 h"
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PMID:35003008 - SUPPORT (IN_VITRO)"After 7 days, 31.2 ± 2.2% of PET was degraded by the three-species microbial consortium"
Pseudomonas EG Detoxification Module
CROSS_FEEDINGP. putida KT2440 was reported to degrade 2 g/L EG within 20 h before addition to the four-member consortium. Exogenous EG inhibited PET hydrolysis but had little effect on bacterial growth. TPA and EG did not accumulate during the reported 2 g/L BHET assay; this is not a PET-film mass balance or proof of complete mineralization, and PET-film TPA transiently increased on day 3.
Source Taxon: Bacillus subtilis 168 Bs_MHETase
Target Taxon: Pseudomonas putida KT2440
Metabolites: ethylene glycol (CHEBI:30742 · MediaIngredientMech · CMMMech)
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
PARTIAL - KT2440 provides EG utilization for the four-member design and can remove an inhibitory hydrolysis product. The study supports EG consumption and product inhibition separately, but changed medium and inoculum prevent assigning the film-weight-loss difference solely to EG removal; four-member film loss was below the three-member LB result.
Evidence
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PMID:35003008 - SUPPORT (IN_VITRO)"After preliminarily verifying the ability of P. putida KT2440 to completely degrade 2 g/L of EG within 20 h"
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PMID:35003008 - SUPPORT (IN_VITRO)"TPA and EG were not accumulated"
Nutrient-Mediated Competition Control
COMPETITIONP. putida dominated recoverable growth after 24 h in rich-media cocultures, motivating a nutrient-poor W-derived medium and inoculum optimization. Wn supplementation and a strongly reduced P. putida inoculum allowed four-member PET degradation; these manipulations do not demonstrate durable coexistence, a unique resource-competition mechanism or species-resolved abundance throughout the 7 day assay.
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
PARTIAL - Medium and inoculum changes constrain the observed P. putida overgrowth and enable measurable four-member PET degradation. The optimized consortium response is experimentally supported, but durable population stability and the separate mediation of each nutrient adjustment were not demonstrated.
Evidence
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PMID:35003008 - SUPPORT (IN_VITRO)"P. putida strongly inhibited growth of the other three bacteria"
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PMID:35003008 - SUPPORT (IN_VITRO)"only P. putida was found."
Four-Member PET Film Degradation
The four-member consortium contains two engineered B. subtilis strains, R. jostii RHA1 and P. putida KT2440: three species, not four. Optimized Wn conditions at 37 C and starting ratio 3:1:10:10^-5 produced 23.2% PET-film weight loss in 7 days. The same-medium comparison supports improved degradation over the two-member module, while the three-member LB consortium achieved 31.2%. Weight loss and metabolite assays do not establish complete carbon mineralization or absence of every intermediate.
Participating Taxa: Bacillus subtilis 168 Bs_PETase, Bacillus subtilis 168 Bs_MHETase, Rhodococcus jostii RHA1, Pseudomonas putida KT2440
Metabolites: poly(ethylene terephthalate) macromolecule (CHEBI:53259 · MediaIngredientMech · CMMMech), terephthalic acid (CHEBI:15702 · MediaIngredientMech · CMMMech), ethylene glycol (CHEBI:30742 · MediaIngredientMech · CMMMech)
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
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PMID:35003008 - SUPPORT (IN_VITRO)"The most suitable temperature was 37°C"
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PMID:35003008 - SUPPORT (IN_VITRO)"a degradation rate of 23.2 ± 2.3%."
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
|
Exact-composition publication - artificial PET degradation consortium
Primary publication defining the PETase, MHETase, R. jostii, and P. putida artificial consortium and reporting PET/BHET degradation phenotypes. |
PHENOTYPE | OTHER | PMID:35003008 |
|
Frontiers article supplementary material
Supplementary tables with strain, plasmid, primer, and medium details for the artificial PET degradation consortia. |
OTHER | OTHER | doi:10.3389/fmicb.2021.778828 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How much of four-member PET degradation is mediated by each product-utilization module under matched medium and inoculum conditions?
Five existing arrows remain as supported biochemical links or bounded contribution inferences. Preserve inhibition perturbations, standalone consumption and film degradation; distinguish BHET from PET, the abstract timing error, rich versus Wn media and transient TPA. Mineralization, durable coexistence and isolated EG-mediated improvement need additional evidence.
Attaches to: ecological_interactions#PETase-MHETase Depolymerization Module, ecological_interactions#Rhodococcus TPA Detoxification Module, ecological_interactions#Pseudomonas EG Detoxification Module, ecological_interactions#Nutrient-Mediated Competition Control, ecological_interactions#Four-Member PET Film Degradation
1 evidence item(s)
After 7 days, 31.2 ± 2.2% of PET was degraded by the three-species microbial consortium
Results timing and endpoint supersede the conflicting three-day abstract wording.
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| PET film substrate | amorphous PET film, 0.25 mm thickness, cut and UV-treated before degradation assays | N/A |
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| TPA and EG product inhibition | terephthalic acid and ethylene glycol inhibit PET degradation | N/A |
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| Wn medium for four-species balance | Wn inorganic salt medium with erythromycin during four-member PET degradation assays | N/A |
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Growth Media
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