Menaquinone Production by Engineering a DegU Quorum Sensing Circuit in Bacillus subtilis

Abstract Vitamin K 2 , as a menadione compound, has been a hot topic in international research in recent years. Previous work mainly focused on the manipulation of several genes in metabolic pathway, but did not pay attention to the overall regulation, which always failed to make the fermentation yield of the strain meet people's requirements. On this basis, we shifted the research focus from the knockout and overexpression of several genes in a single metabolic pathway to the overall regulation of bacteria. The effect of transcription regulation system on MK-7 production in Bacillus subtilis was studied by mining transcription regulation factors. We constructed a set of PhrG-RapG-DegU regulatory system by using quorum sensing signal molecules PhrG pentapeptide, RapG protein and regulatory factor DegU. By fine-tuning the expression of related genes, the content of MK-7 in the finally constructed BS06 in a 250 mL conical flask reached 102.47 mg/L, and the cell density was 28.677, which was basically the same as that of the original bacteria. Our experiment realized the efficient synthesis of MK-7 in Bacillus subtilis and ensured the stable growth of bacteria, which proved the effectiveness of this control strategy.