High-efficiency cellulosic biocatalysts constructed via Pichia pastoris surface display

Abstract

The high cost and limited stability of cellulases pose significant barriers to their industrial application in biomass conversion. Yeast surface display technology offers a promising approach for constructing reusable whole-cell catalysts; however, the compatibility between different anchor proteins and specific cellulase components remains unclear. In this study, Pichia pastoris X33 was used as the host strain to construct nine recombinant strains by fusing three anchor proteins (PIR1, SED1, AGA1) with endoglucanase (EG), cellobiohydrolase (CBH), and beta-glucosidase (BGL), respectively. Notably, PIR1 demonstrated markedly higher display efficiency for all three enzymes compared to SED1 and AGA1. Notably, the EG-PIR1 combination achieved the highest display efficiency, reaching 91.5% as quantified by flow cytometry. Following fermentation optimization, enzyme activity surged to 0.594 U/mL, marking a 42.2% improvement over pre-optimization levels. Furthermore, the surface-displayed enzymes retained over 75% relative activity after six consecutive cycles of reuse. This study quantitatively elucidates the adaptation patterns between anchor proteins and cellulase components, providing a theoretical foundation and technical pathway for the rational design of highly efficient whole-cell biocatalysts.