Rational chromosome engineering of Escherichia coli for overproduction of salidroside

Salidroside is a naturally occurring phenylpropanoid glycoside which widely used in food and cosmetics. The development of microbial synthesis of salidroside is limited due to the low titer and the addition of inducers and antibiotics. Based on our previously constructed high tyrosol-producing recombinant Escherichia coli, we identified the catalytic activity of glycosyltransferase UGT85A1 was high. The strain carrying plasmid pKK223UGT85A1 produced 2.5 g/L of salidroside in shake flask. To construct a stable, non-inducible, antibiotic-free salidroside-producing strain, UGT85A1 gene was integrated into genomic sites and the single-copy strain could only produce about 120 mg/L of salidroside. Therefore, we designed a multi-copy integration strategy and obtained an eight-copy number recombinant strain 5A8S. The production of salidroside also increased sequentially and the strains grew well. When the strain 5A8S was cultured in a shake flask, the salidroside production reached 2.42 g/L. Then, we carried out a scale-up culture of strains 5A-UGT85A1 and 5A8S in a 5 L fermenter, and the salidroside titers were 9.48 and 9.34 g/L, respectively. In this study, a non-inducible high-yield salidroside recombinant strain was successfully constructed using a multi-copy integration strategy in the non-coding region of the genome, thus laying the foundation for efficient green biosynthesis of salidroside.

Automated summary

In this study, a high-yield recombinant strain of Salidroside was successfully constructed using a multi-copy integration strategy in the non-coding region of the genome, laying the foundation for efficient green biosynthesis of Salidroside.