Thermostable Bacterial Esterases From Lipase Family 1.5 Degrade Compostable Polyesters PBAT and PBSA

Area of Science:

• Biochemistry
• Environmental Science
• Microbiology

Background:

• The global plastic crisis demands sustainable recycling solutions, with enzymatic hydrolysis being a key area of research.
• Current efforts focus on polyethylene terephthalate (PET)-degrading enzymes (PETases), but other polyesters also contribute to environmental pollution.

Purpose of the Study:

• To discover and characterize novel thermostable enzymes with polyesterase activity from the bacterial Lipase Family 1.5.
• To evaluate the degradation capabilities of these newly identified enzymes against various polyesters, including polybutylene succinate co-terephthalate (PBAT) and polybutylene succinate co-butylene adipate (PBSA).

Main Methods:

• Phylogenetic and sequence analysis of bacterial esterases to identify potential polyester-degrading enzymes.
• Heterologous expression of identified enzymes in Escherichia coli.
• Enzymatic activity screening against different polyester types (PBAT, PBSA, PET) under controlled conditions.

Main Results:

• Discovery of previously uncharacterized, thermostable enzymes from Lipase Family 1.5 with significant polyesterase activity.
• These enzymes effectively degrade PBAT and PBSA, with notably higher efficacy against the aliphatic polyester PBSA.
• Three specific enzymes achieved complete solubilization of 5 mg/mL PBSA within 48 hours at a low enzyme concentration (100 nM).
• Limited activity was observed against PET.

Conclusions:

• Lipase Family 1.5 represents a promising source of novel, thermostable enzymes for industrial polyester degradation.
• These enzymes demonstrate potential for efficient recycling of polyesters like PBSA and PBAT, reducing reliance on extensive protein engineering.
• The findings highlight the value of exploring natural biodiversity for sustainable waste management solutions.