Engineering Saccharomyces cerevisiae for continuous secretory production of hEGF in biofilm.

Human epidermal growth factor (hEGF) plays a crucial role in promoting cell growth and has various clinical applications. Due to limited natural sources and the high cost of chemical synthesis, researchers are now exploring genetic engineering as a potential method for hEGF production. In this particular study, a novel hEGF expression system was developed using Saccharomyces cerevisiae. This system involved optimizing the promoter and signal peptide and deleting protease-coding genes PEP4, PRB1, and YAP3, overexpressing chaperones KAR2 and PDI1 in the protein secretion pathway, which led to a 2.01-fold increase in hEGF production compared to the wild type strain. Furthermore, biofilm-forming genes FLO11 and ALS3 were integrated to create a biofilm strain with adhesive properties. A biofilm-based immobilized continuous fermentation model was established to leverage the characteristics of this biofilm strain. Each batch of this model yielded 130 mg/L of hEGF, with a production efficiency of 2.71 mg/L/h - surpassing the production efficiency of traditional free fermentation (1.62 mg/L/h). This study presents a promising fermentation model for efficient hEGF production based on biofilm characteristics, offering valuable insights for the application of biofilm fermentation in the production of small molecule peptides.