| Summary: | A polyethylene terephthalate (PET)-degrading bacterium identified as <i>Stenotrophomonas maltophilia</i> PRS8 was isolated from the soil of a landfill. The degradation of the PET bottle flakes and the PET prepared as a powder were assessed using live cells, an extracellular medium, or a purified cutinase-like enzyme. These treated polymers were analyzed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The depolymerization products, identified using HPLC and LC-MS, were terephthalic acid (TPA), mono(2-hydroxyethyl)-TPA (MHET), and bis(2-hydroxyethyl)-TPA (BHET). Several physicochemical factors were optimized for a better cutinase-like enzyme production by using unique single-factor and multi-factor statistical models (the Plackett–Burman design and the central composite design software). The enzyme was purified for homogeneity through column chromatography using Sephadex G-100 resin. The molecular weight of the enzyme was approximately 58 kDa. The specific activity on para nitrophenyl butyrate was estimated at 450.58 U/mg, with a purification of 6.39 times and a yield of 48.64%. The enzyme was stable at various temperatures (30–40 °C) and pH levels (8.0–10.0). The enzyme activity was significantly improved by the surfactants (Triton X-100 and Tween-40), organic solvent (formaldehyde), and metals (NiCl<sub>2</sub> and Na<sub>2</sub>SO<sub>4</sub>). The extracellular medium containing the cutinase-type enzyme showed a depolymerization yield of the PET powder comparable to that of <i>Idonella skaiensis Is</i>PETase and significantly higher than that of <i>Humicola insolens</i> thermostable HiCut (HiC) cutinase. This study suggests that <i>S. maltophilia</i> PRS8 is able to degrade PET at a mesophilic temperature and could be further explored for the sustainable management of plastic waste.
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