This application relates to the field of
genetically engineered bacteria technology, specifically disclosing a
genetically engineered *E. coli* strain for producing
emodin, its construction method, and its applications. This application uses *E. coli* BAP1 as the substrate strain. This strain carries its own sfp in its
genome, which can be used to activate
polyketide synthase. Furthermore, *E. coli* itself grows rapidly, has a vigorous
metabolism, and the culture medium is low-cost, facilitating high-density
fermentation. Through
gene editing, the uptake and utilization of glucose are improved, the flux of
acetic acid and
lactic acid diverted from pyruvate is reduced, and the ATP supply is enhanced to increase the flux of acetyl-CoA and malonyl-CoA within the
bacteria. This provides sufficient substrate for the synthesis of
emodin by
polyketide synthase,
thioesterase, and decarboxylase, thereby increasing the yield of
emodin. The emodin yield achieved by this application through shake-flask
fermentation reaches 576.4 mg / L, which is currently the highest level in the *E. coli*
system.