Ya Li

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.

Talaromyces pinophilus is a filamentous fungus with notable lignocellulose-degrading capacity based on enzyme activities and protein secretion potential, making it a compelling candidate for industrial biotechnology applications. In this study, we present the genomic characterization of the highly cellulolytic strain Y117, a domesticated variant of T. pinophilus, based on whole-genome sequencing and comparative genomic analysis with eleven related strains. Comprehensive analysis of CAZymes, transcription factors, and secondary metabolite diversity in T. pinophilus strains revealed that the exceptional lignocellulose degradation capacity of Y117 is driven by its unique genomic architecture. Key genomic features that distinguish Y117 include (1) significant expansion of glycoside hydrolase (GH) and carbohydrate-binding module (CBM) families, (2) loss of fungal-RiPP-like clusters, and (3) absence of the developmental regulator BrlA. These genomic adaptations could indicate a metabolic trade-off favoring hydrolytic enzyme production over secondary metabolism and sporulation. Our findings provide fundamental insights into fungal lignocellulose degradation mechanisms while establishing Y117 as a promising chassis for metabolic engineering applications in industrial enzyme production and heterologous protein expression.