Metabolic Engineering of the MEP Pathway in <i>Bacillus subtilis</i> for Increased Biosynthesis of Menaquinone-7

Abstract

Vitamin K is essential for blood coagulation and plays important roles in bone and cardiovascular health. Menaquinone-7 (MK-7) is one form of vitamin K that is especially useful due to its long half-life in the circulation. MK-7 is difficult to make <i>via</i> organic synthesis, and is thus commonly produced by fermentation. This study aimed to genetically modify <i>Bacillus subtilis</i> cultures to increase their MK-7 yield and reduce production costs. We constructed 12 different strains of <i>B. subtilis</i> 168 by overexpressing different combinations of the rate-limiting enzymes Dxs, Dxr, Idi, and MenA. We observed an 11-fold enhancement of production in the best-performing strain, resulting in 50 mg/L MK-7. Metabolite analysis revealed new bottlenecks in the pathway at IspG and IspH, which suggest avenues for further optimization. This work highlights the usefulness of <i>Bacillus subtilis</i> for industrial production of high value compounds.