Abstract

Vitamin K2 (Menaquinone) is an essential vitamin existing in the daily diet, and Menaquinone-7 (MK-7) is an important form of it. In a recent work, we have engineered the synthesis modules of MK-7 in Bacillus subtilis, and the strain BS20 can produce 360 mg/l MK-7 in shake flasks, while the Methylerythritol Phosphate (MEP) pathway, which provides the precursor isopentenyl diphosphate for MK-7 synthesis, was not engineered. In this study, we overexpressed five genes of MEP pathway in BS20 and finally obtained a strain (BS20DFHG) with MK-7 titer of 415 mg/l in shake flasks. Next, we optimized the fermentation process parameters (initial pH, temperature and aeration) in an 8-unit parallel bioreactor system consisting of 300 ml glass vessels. Based on this, we scaled-up the MK-7 production by the strain BS20DFHG in a 50-l bioreactor, and the highest MK-7 titer reached 242 mg/l. Here the engineered strain BS20DFHG may be used for the industrial production of MK-7 in the future.

【From】 PubMed