Original Research ArticleBiotin-independent strains of Escherichia coli for enhanced streptavidin production

- Biotin-independent strains of E. coli and C. glutamicum are created.
- A malonyl-CoA bypass circumvents the requirement of previously essential biotin.
- Biotin-independent strains are used for improved production of streptavidin.
- A process is developed delivering the highest streptavidin titers to date.

Biotin is an archetypal vitamin used as cofactor for carboxylation reactions found in all forms of life. However, biotin biosynthesis is an elaborate multi-enzymatic process and metabolically costly. Moreover, many industrially relevant organisms are incapable of biotin synthesis resulting in the requirement to supplement defined media. Here we describe the creation of biotin-independent strains of Escherichia coli and Corynebacterium glutamicum through installation of an optimized malonyl-CoA bypass, which re-routes natural fatty acid synthesis, rendering the previously essential vitamin completely obsolete. We utilize biotin-independent E. coli for the production of the high-value protein streptavidin which was hitherto restricted because of toxic effects due to biotin depletion. The engineered strain revealed significantly improved streptavidin production resulting in the highest titers and productivities reported for this protein to date.