Fig. 1

Schematic representation of the industrial host SCK22 harboring plasmid pHT7. After xylose induction, under the control of xylose-inducible promoter, comK gene was expressed and then super receptive cells were formed. Endogenous protein genes and fermentation-related genes were knocked out on the genome to make it suitable for high-density fermentation. The P₄₃ promoter enabled the constitutive expression of T7 RNA polymerase, and the expression plasmid encoded the target gene, where the T7 promoter was under the control of the lac operon