Thermostability Enhancement of the GH11 Xylanase XynZT-1 from <i>Alteromonas macleodii</i> HY35 Achieved via Modular Mosaic Engineering

β-1,4-Xylanase is crucial for the bioprocessing of lignocellulosic biomass owing to its ability to degrade xylan, which is the primary component in hemicellulose. Nonetheless, its industrial application is hampered by inherent limitations in thermostability. To overcome this challenge, the xylanase XynZT-1 from Alteromonas macleodii HY35 was engineered to enhance its thermal stability via modular mosaic assembly. The engineered XynZ1, XynZ2, XynZ3, and XynZ4 demonstrated considerable improvement, and their optimal temperatures were increased from 45 °C in XynZT-1 to 85, 75, 75, and 70 °C, respectively. Furthermore, when compared with XynZT-1, XynZ1, XynZ2, XynZ3, and XynZ4 showed 21.7-, 17.8-, 12.4-, and 11.8-fold increases in t 1/2 50 °C and catalytic efficiency, respectively. The birchwood xylan hydrolysis assay confirmed the exceptional catalytic efficiency and thermostability of XynZ1, XynZ2, XynZ3, and XynZ4, highlighting their potential for industrial application, particularly in pulp prebleaching processes. These findings affirm that modular chimeric assembly is an effective engineering strategy for improving the performance of GH11 xylanases.