Liu_2026_Int.J.Biol.Macromol__153549

Enzymatic recycling has been proposed as an alternate strategy to polyurethane (PU) waste management. However, the bulk of previously known PU-degrading enzymes were classed as thermophilic or mesophilic enzymes, with cold-adapted enzymes being uncommon. In this study, we identified a cold-adapted lipase, PSLA, from Pseudomonas sp. BIT-r11, a strain isolated from the gut bacterium of plastic-eating superworms. PSLA exhibited optimal activity at 15 degreesC and retained more than 40% of its relative activity at 0 degreesC, showing typical cold-adapted characteristics. Differential scanning fluorimetry showed that PSLA had a T(m) of 35.5 degreesC, corresponding to a pronounced temperature gap between T(m) and T(opt) (T(g) = 20.5 degreesC), which is consistent with a commonly observed feature of cold-adapted enzymes. Under optimal conditions (15 degreesC, pH 7.0), PSLA degraded 49.56 +/- 3.74% of a dispersed polyester-PU emulsion (Impranil(a) DLN-SD) within 15 min and caused 1.20 +/- 0.03% weight loss of solid polyester PU foam within 5 days. Molecular dynamics simulations further revealed increased N- and C-terminal flexibility and greater N/C-terminal separation at 15 degreesC; distance-restrained MD also showed that PSLA more readily maintained a near-attack S207-substrate geometry at 15 degreesC than at 30 degreesC. Consistently, kinetic analysis showed that PSLA had a lower K(m) and higher k(cat)/K(m) at 15 degreesC than at 30 degreesC, indicating enhanced apparent substrate affinity at low temperature. These results indicate that PSLA expands the available enzyme resources for low-temperature PU biodegradation and may support PU waste treatment in high-latitude, alpine, or other cold environments.