Abstract

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. In this study, a cellulase-hyperproducing mutant of Talaromyces pinophilus, Y117, was generated from the parental strain TP117 via sequential ultraviolet irradiation and NTG (N-methyl-N′-nitro-N-nitrosoguanidine) 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 lactate dehydrogenase A (ldhA) gene from Rhizopus oryzae was heterologously expressed in Y117 to direct hydrolyzed sugars toward lactic acid (LA). Y117 exhibited significantly enhanced enzymatic secretion, achieving FPase activity of 8.9 IU/mL and a substrate utilization rate 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). While LA productivity and yield currently remain below bacterial benchmarks, the unique CBP capability of Y117 provides a foundation for further metabolic engineering toward industrial viability. The engineered T. pinophilus Y117 demonstrates promising potential as a CBP platform for efficient straw-to-LA conversion, providing a sustainable approach for third-generation biobased materials production.

IPC Classification

Keywords