Synergistic Enhancement of Straw Hydrolysis and Lactic Acid Production in Talaromyces pinophilus Through Combined Random Mutagenesis and Plasmid Reconstruction

Abstract:Background: Lignocellulosic biorefineries are limited by the high cost of cellulolytic enzymes. Consolidated bioprocessing (CBP), which integrates saccharification and fermentation in one step, offers a solution to this challenge.Methods: In this study, a cellulase-hyperproducing mutant of Talaromyces pinophilus, Y117, was generated from the parental strain TP117 via sequential ultraviolet irradiation and NTG mutagenesis. Enzymatic secretion and lignocellulose degradation capacities were evaluated, focusing on agricultural residues, particularly corncob. Y117's performance was compared with TP117 and Trichoderma reesei Rut-C30 (TR30) under high-solids fermentation. Furthermore, the ldhA gene from Rhizopus oryzae was heterologously expressed in Y117 to direct hydrolyzed sugars toward lactic acid (LA).Results: Y117 exhibited significantly enhanced enzymatic secretion, achieving FPase activity of 8.91 IU/mL and a substrate conversion efficiency of 72.2% at 125 g/L corncob solids. Y117 outperformed TP117 and TR30 in cellulase, xylanase, and CMCase activities, as well as growth under high-solids fermentation conditions. In the LA fermentation process, Y117 produced 14.20 g/L LA, a notable improvement compared to TP117 (5.33 g/L) and TR30 (2.71 g/L).Conclusions: The engineered T. pinophilus Y117 demonstrates excellent potential as a CBP platform for efficient straw-to-LA conversion, providing a sustainable approach for third-generation biobased materials production.