Menaquinone-7 production by engineered Saccharomyces cerevisiae through de novo Synthesis and fermentation optimization.

Menaquinone-7 (MK-7), a highly preferred form of vitamin K2, has garnered extensive attention due to its long half-life in the human body and numerous nutritional and pharmacological benefits. To establish a cost-effective microbial platform for MK-7 production, we engineered the eukaryotic model organism Saccharomyces cerevisiae. The complete biosynthesis pathway was modularized into three parts: the endogenous mevalonate (MVA) pathway, the endogenous shikimate (SA) pathway, and a heterologous menaquinone (MK) module. Eleven key genes from the MK module were introduced into the yeast chassis using selection markers for His, Leu, and Met, creating the engineered strain YK-1. We then optimized the fermentation medium and conditions, and the MK-7 titer reached 0.413 mg/L. This represents a 31.1% increase over the non-optimized yield, demonstrating the successful de novo synthesis of MK-7 from simple carbon sources in a eukaryotic cell factory. This work not only expands the repertoire of chassis cells for MK-7 production but also provides a valuable framework for engineering biosynthesis pathways for other isoprenoids.