Characterization and Engineering of a Fungal Poly(ethylene terephthalate) Hydrolyzing Enzyme from Aspergillus fumigatiaffinis

As our environmental pollution awareness
increases, effective
poly(ethylene
terephthalate) (PET) waste management has become an important global
goal, and biorecycling is considered as one of the strategies for
PET recycling. Although several bacterial cutinases have been investigated
with respect to PET hydrolysis, fungal cutinases and their potential
still need to be explored. Here, we screened 15 fungal cutinases and
discovered a cutinase from Aspergillus fumigatiaffinis (AfC), a potent PET hydrolase satisfying PET hydrolytic activity
and thermal stability. Structural analysis of AfC revealed that the
enzyme has an additional disulfide bond compared to known fungal cutinases.
We also developed the AfCT37V/A84K/N117E/N124E/A171P/N182E variant (AfC6p), which showed enhanced thermal stability
and a 4-fold increase in PET hydrolytic activity at 60 °C compared
with AfCWild‑type. AfC6p completely decomposed
the postconsumer PET film within 12 days at 60 °C.