Liang_2025_Int.J.Biol.Macromol_330_148111

The production cost of catalysts is critical for industrializing sustainable PET plastic recycling technologies, with industrial enzyme preparation costs largely dependent on target enzyme expression levels and post-fermentation processing expenses. This study developed a high-efficiency secretory expression system for PET hydrolytic enzymes in Bacillus amyloliquefaciens 205, an industrially robust strain. Three enzyme variants, LCC(ICCG), TurboPETase, and FAST-PETase, were codon-optimized and expressed using the host's endogenous secretory expression machinery. LCC(ICCG) and TurboPETase achieved superior extracellular yields of 3.2 g/L and 1.6 g/L in a 5 L fermenter, respectively, representing the highest reported levels for PET hydrolytic enzymes. It also presents the first report of the efficient secretory expression of PETases in Bacillus amyloliquefaciens. Besides, the crude enzyme supernatant of TurboPETase directly degraded PET films achieving complete degradation within 24 h at 65 degreesC and pH 8.0. Scaling to a 5 L bioreactor, 50 g of commercial PET was fully depolymerized using 1 (w/w) crude TurboPETase solution within 24 h, validating its industrial viability. This work establishes B. amyloliquefaciens 205 as a scalable platform for secretory enzyme production and demonstrates the feasibility of crude enzyme-based PET recycling, offering a sustainable solution to global plastic waste challenges.