Advances in Menaquinone-7 Production by Bacillus subtilis Natto: Fed-Batch Glycerol Addition

Menaquinone-7 was produced by fermentation mainly using Bacillus subtilis species. Due to the low concentration of menaquinone-7 in fermentation processes and the associated expense of recovering the menaquinone-7, it was desirable to improve the fermentation concentration. The aim of this study was to determine the effect of fed-batch glycerol addition in the production of menaquinone-7 during the fermentation of Bacillus subtilis natto in both small (25-mL) and bench scale (3-L) fermenters. Liquid phase fermentation was carried out aerobically at 40°C for a period of 6 days. The pH, bacterial growth, glycerol and menaquinone-7 concentrations were measured every day. Maximum menaquinone-7 was produced when 2% (w/v) glycerol was added to the fermentation media in the second day (48 h) of fermentation. The results were demonstrated 40% increase of menaquinone-7 concentration compared to batch culture. This study provides valuable data for further optimization and scale-up the menaquinone-7 fermentation process.