An Inducible Komagataella Phaffii System for Protein Expression Using Sorbitol Dehydrogenase Promoter.

Objectives The aim of the present work was to develop a methanol-independent Komagataella phaffii ( K. phaffii ) strain using a non-methanol promoter. Results In this study, the food grade enzyme xylanase from Aspergillus niger ATCC 1015 was used as the reporter protein, a recombinant K. phaffii containing a cascade gene circus was designed and constructed using sorbitol as inducer. Sorbitol induced P SDH leading to MIT1 expression firstly, and heterologous protein xylanase expression finally. This system showed 1.7 fold of xylanase activity at the condition of single copy number of extra MIT1 , and 2.1 fold of xylanase activity at condition of multi-copy extra MIT1 gene. Conclusions This sorbitol-induced expression system of K. phaffii avoided toxic and explosive methanol. It was a novel cascade gene expression and a food safety system.