Fine-tuning the pathway and fermentation conditions to explore Pichia pastoris for high-level d-arabitol production...

The bioproduction of d-arabitol has recently attracted considerable attention due to its potential applications in the food, chemical, and pharmaceutical industries. However, current technologies, primarily employing unconventional osmotolerant yeasts and traditional strain-improvement strategies, face challenges such as low conversion efficiency, instability, and limited industrial adaptability. Thus, developing robust chassis through precise rational metabolic engineering is essential for enhancing the overall efficiency and sustainability of this bioproduction process. In this regard, Pichia pastoris, a widely used host for heterologous protein production, was systematically and rationally engineered in this study by overexpressing key metabolic enzymes involved in d-arabitol biosynthesis and fine-tuning promoters and gene copy numbers. Through this metabolic re-modulation and subsequent bioprocess optimization, a final d-arabitol titer of 78.1 g/L was achieved during fed-batch fermentation in a bioreactor. These findings underscore the significant potential of employing P. pastoris as a new and robust chassis for advancing d-arabitol biosynthesis.