Utilization of glucose-based medium and optimization of Bacillus subtilis natto growth parameters for vitamin K (menaquinone-7) production in biofilm reactors

Menaquinone-7 (MK-7) is the most potent form of vitamin K prescribed as a dietary supplement. MK-7 is commonly produced via static fermentation of Bacillus subtilis natto. The fermentation of this bacterium is associated with formation of large amounts of pellicles and biofilm, which are effective in MK-7 production, but also result in significant heat and mass transfer challenges during the scale-up process. Thus, the objectives of this study were to develop and evaluate the possibility of using a biofilm reactor for MK-7 production. In this research, biofilm reactors were constructed using the Plastic Composite Supports (PCS). In order to optimize the fermentation parameters for MK-7 production, Central Composite Design (CCD) was carried out along with supplementary runs to determine the optimum temperature, pH, and agitation. The biofilm reactors were able to produce a maximum concentration of 18.45 ± 0.76 mg/L of MK-7, which was 237% higher than the suspended-cell fermentation. Therefore, the present work suggests the possibility of using biofilm reactors as a new and effective fermentation strategy to address the issues associated with MK-7 fermentation.