A Research On Antibiotic Iso-migrastatin Fermentation Condition Optimization And The Mechanism Of Titer Improvement

Iso-migrastatin (iso-MGS), the 12-membered glutarimide-containing polyketide, was isolated from S. pLatensis NRRL18993 fermentation broth with the bioactivity against cancer cells migration. Five engineered strains were constructed upon introduction of the vector pBS11001 harboring the entire mgs biosynthetic gene cluster into five mode strains, which successfully heterologously biosynthesized iso-MGS production.The purpose of this work is to improve iso-MGS production titers in five engineered strains by fermentation condition optimization. iso-MGS production titers were improved by 3-18 fold in five engineered strains after optimization. And SB11001 proved itself to yield the highest iso-MGS production 128.6 mg/L, which was chosen to be the candidate strain for further recombinant biosynthesized iso-MGS production. Exchanging the carbon sources between B2 medium and R2YE medium resulted in the hybrid B2 medium, in which iso-MGS production titer was further increased to 186.7 mg/L. The hybrid B2 medium provided the possibility for heterologously biosynthesizing other natural products. According to the proposed biosynthetic pathway for iso-MGS, 2 g/L NaHCO3 as the proposed precursor added to the fermentation broth further increased the iso-MGS production to 207.8 mg/L. Real Time quantitative RT-PCR demonstrated the relationship between the 11 genes in mgs cluster transcriptional level and iso-MGS production titers in wild strain and engineered strains at different phase. In order to select the targeted engineered genes for further recombinant biosynthesis iso-MGS production.