Enzyme Engineering & Biocatalysis
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Enzymatic PET Depolymerisation
PET-Degrading Enzyme
Does LCC-ICCG-NM maintain its depolymerisation rate advantage over LCC-ICCG on post-consumer PET flake conditioned from 12 to 39% crystallinity at 65 °C?
THE QUESTION
Which mutation set to LCC-ICCG-NM — the 2025 loop-reconstruction benchmark at 90% conversion — raises depolymerisation rate on 40%-crystalline post-consumer PET at 65 degrees C by 5-fold while retaining more than 80% activity at 24 hours?
WORK ORDER
Rate-versus-crystallinity estimate for LCC-ICCG and LCC-ICCG-NM on graded post-consumer PET flake at 65 °C
BACKGROUND
What this Apodex Lab is
Post-consumer poly(ethylene terephthalate) waste is semicrystalline, with packaging flake typically sitting between 30 and 40 percent crystallinity. Enzymatic recycling seeks to break this plastic down into terephthalic acid at moderate temperatures without energy-intensive melting. However, crystalline polymer packing resists enzymatic attack. Plant operators must decide whether to invest capital in high-temperature thermal amorphisation trains before digestion or rely on engineered enzymes that can depolymerise crystalline feedstock directly.
The standard benchmarks for enzymatic depolymerisation are engineered derivatives of leaf-branch compost cutinase, notably the template LCC-ICCG and its loop-reconstructed variant LCC-ICCG-NM. Published comparisons rank these enzymes on near-amorphous substrates, where LCC-ICCG-NM reaches about 90 percent overall conversion compared to roughly 85 percent for the template. The only detailed crystallinity sensitivity data for benchmark cutinases cover roughly 8.5 to 12 percent crystallinity at 50 °C. No published depolymerisation rate exists for any engineered cutinase on untreated post-consumer flake across the 30 to 40 percent crystallinity band at 65 °C with more than 80 percent residual activity retained at 24 hours. Whether loop-reconstruction gains survive on real semicrystalline waste remains unmeasured.
The PET-Degrading Enzyme Apodex Lab measures initial depolymerisation rates and conversion profiles for purified LCC-ICCG and LCC-ICCG-NM across five verified crystallinity bins spanning about 12 to 39 percent. Acting on a single post-consumer flake consignment milled to a 150-300 µm sieve fraction at 65 °C, the campaign quantifies the release of terephthalic acid and mono(2-hydroxyethyl) terephthalate using reverse-phase HPLC. These measurements establish the enzyme mass required per tonne of polymer for 50 percent conversion in 24 hours. The resulting dose-response curve determines whether to procure further mutation sets targeted at crystalline substrate or reallocate engineering effort toward upstream amorphisation pre-treatment.
WHY NOW
Why the field is spending on an assumption
Enzyme-driven PET recycling benchmarks rely on cutinases such as LCC-ICCG and its loop-reconstructed derivative LCC-ICCG-NM, ranked by conversion percentages on near-amorphous polymer films. Real untreated post-consumer flake sits near 30 to 40 percent crystallinity, where crystalline domains resist enzymatic attack. Because past assays used self-prepared amorphised substrates without standardised crystallinity reporting, rates are not comparable across laboratories. Published guidelines for assay reporting and protocols for handling untreated post-consumer plastic now allow direct attribution of reaction rates to substrate morphology. The field cannot currently state at what crystallinity an engineered cutinase loses its kinetic advantage, nor the enzyme mass per tonne required to depolymerise semicrystalline flake.
WHAT WE’D BUY
What we would ask a laboratory to run
We are not buying the answer. We are buying a measurement with an interval — and the bars it will be compared against.
Two purified cutinases, LCC-ICCG and LCC-ICCG-NM, are incubated at 65 °C with untreated post-consumer PET flake milled to 150–300 µm and conditioned into five crystallinity bins from about 12 to 39%, verified by calorimetry and X-ray diffraction. Liquid chromatography quantifies released terephthalic acid and mono(2-hydroxyethyl) terephthalate. The laboratory delivers the initial rate ratio of the two enzymes across each bin, with a pooled 95% confidence interval width under 0.30 absolute for bins at or above 33% crystallinity. It also returns the enzyme mass per tonne of polymer required for 50% conversion in 24 hours at each bin, with 95% intervals within 1.5-fold of point estimates, alongside 24-hour residual enzyme activity and surface-area-normalised rates.
SCOPE & LIMITS
Because the substrate is milled to 150–300 µm and annealed under controlled laboratory conditions, absolute depolymerisation rates represent an upper bound and mass doses per tonne represent a lower bound relative to coarse industrial flake.
WHO EXECUTES
The kind of lab that can run this
A biocatalysis and polymer-characterisation contract laboratory able to express and purify thermostable cutinase variants, prepare and characterise post-consumer PET flake of graded crystallinity by DSC and XRD, and quantify terephthalic acid and MHET release by HPLC at 65 degrees C over multi-day incubations.
EXECUTOR KIND
wet-lab
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