O-acetyl-L-homoserine (OAH) is a promising platform compound for the production of L-methionine and other valuable compounds, while its low yield and low conversion rate limit the industrial application. To solve these problems, we constructed a strain for high OAH production with the previously constructed L-homoserine producer Escherichia coli HS33 as the chassis by systematic metabolic engineering. Firstly, PEP accumulation, pyruvate utilization, and OAH synthesis pathway (overexpressing aspB, aspA, and thrA^C1034T) were enhanced to obtain an initial strain accumulating 13.37 g/L OAH. Subsequently, the co-factor synthesis genes were integrated to supply reducing power and energy, which increased the yield to 15.79 g/L. The OAH yield of the engineered strain OAH28 was further increased to 17.49 g/L by strengthening the acetic acid reuse pathway, improving the supply of acetyl-CoA, and regulating the expression of MetX from different sources. Finally, in a 5 L fermenter, OAH28 achieved an OAH titer of 47.12 g/L, with a glucose conversion rate of 32% and productivity of 0.59 g/(L·h). The results lay a foundation for increasing the OAH production by metabolic engineering and give insights into the industrial production of OAH.
Metabolic Engineering/methods* ; Escherichia coli/genetics* ; Homoserine/biosynthesis* ; Fermentation

Influenza(flu)is an acute respiratory infection caused by influenza viruses,characterized by high morbidity,strong trans-mission and general susceptibility of the population,and often accompanied by clinical symptoms such as fever,cough and muscle aches,etc.With the global pandemic of influenza,it has become a major challenge in the field of global public health,and therefore,it is particularly important to explore effective treatment methods.Chinese medicine has thousands of years of experience in treating in-fectious diseases and plays an important role in the prevention and treatment of influenza.This paper provides a comprehensive and systematic review of the Chinese medicine name,etiology,identification and typing,treatment methods and mechanism of action of in-fluenza,aiming to make up for the lack of the current summary of Chinese medicine treatment of influenza,with a view to providing cer-tain ideas and theoretical basis for the study of Chinese medicine treatment of influenza.

Influenza(flu)is an acute respiratory infection caused by influenza viruses,characterized by high morbidity,strong trans-mission and general susceptibility of the population,and often accompanied by clinical symptoms such as fever,cough and muscle aches,etc.With the global pandemic of influenza,it has become a major challenge in the field of global public health,and therefore,it is particularly important to explore effective treatment methods.Chinese medicine has thousands of years of experience in treating in-fectious diseases and plays an important role in the prevention and treatment of influenza.This paper provides a comprehensive and systematic review of the Chinese medicine name,etiology,identification and typing,treatment methods and mechanism of action of in-fluenza,aiming to make up for the lack of the current summary of Chinese medicine treatment of influenza,with a view to providing cer-tain ideas and theoretical basis for the study of Chinese medicine treatment of influenza.