Aims
Study of the effect of isoleucine on the biosynthesis of FK506 and modification of its producing strain to improve the production of FK506.
Methods and results
Metabolomics analysis was conducted to explore key changes in the metabolic processes of S. tsukubaensis Δ68 in medium with and without isoleucine. In-depth analysis revealed that the shikimate pathway, methylmalonyl-CoA and pyruvate might be the rate-limiting factors in FK506 biosynthesis. Overexpression of involved gene PCCB1 in S. tsukubaensis Δ68, a high-yielding strain Δ68-PCCB1 was generated. Additionally, the amino acids supplement was further optimized to improve FK506 biosynthesis. Finally, FK506 production was increased to 929.6 mg·L−1, which was 56.6% higher than that in the starter strain, when supplemented isoleucine and valine at 9 g·L−1 and 4 g·L−1, respectively.
Conclusions
Methylmalonyl-CoA might be the key rate-limiting factors in FK506 biosynthesis and overexpression of the gene PCCB1 and further addition of isoleucine and valine could increase the yield of FK506 by 56.6%.