Engineering a thermophilic Bacillus thermoamylovorans for degradation of polyethylene terephthalate waste

Biodegradation presents a sustainable alternative for recycling polyethylene terephthalate (PET) waste. Enzymatic PET degradation typically requires enzyme preparation, which limits its industrial applicability. Herein, we developed a novel thermophilic biocatalyst using Bacillus thermoamylovorans JQ3, engineered to express PET hydrolase, capable of simultaneous enzyme secretion and PET degradation. The engineered strain harboring PET hydrolase variant from the bacterium HR29 (TurboPETase), achieved up to 100 % weight loss of PET at 60 °C. It exceeded the sum of the degradation rates (17.7 %) of the wild strain and TurboPETase treatment alone, representing the highest degradation rate among previously reported engineered strains. Moreover, this engineered strain demonstrated broad specificity for various polyester plastics, with biocatalytic activity 10- to 50-fold higher than that of the wild strain. Nearly 100 % degradation of polycaprolactone (PCL) was observed at a solids loading of 10 g/L. This study establishes B. thermoamylovorans as a promising platform for developing environmentally friendly biocatalytic approaches to address plastic waste challenges, paving the way for more sustainable plastic degradation and recycling solutions.