Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Abstract. Menaquinone-7 (MK-7) is a subtype of vitamin K which plays a key role in promoting heart and bone health. MK-7 can be excreted by many strains of bacteria. Among these strains, Bacillus subtilis natto seems to hold a key position. On the other hand, Bacillus subtilis, especially in static fermentations, tends to form pellicles and possibly biofilms under suitable conditions which promote MK-7 secretion but at the same time create operational and scaling up issues during fermentation. Therefore, biofilm reactors seem to be a viable strategy to create a controlled environment for the bacteria to form biofilm and simultaneously address operational and scaling up issues through robust agitation and aeration. The present study aims at using a suitable Plastic Composite Support (PCS) and Bacillus strain to optimize the media components and growth conditions in a glucose-based medium using a biofilm reactor. The optimum conditions were found as 30°C, 234 rpm and pH 6.48, and the optimum composition was of glucose (152.6 g/L), yeast extract (8 g/L) and casein (17.6 g/L) yielding a maximum MK-7 concentration of 20.46±0.51 mg/L in batch biofilm reactors Furthermore, MK-7 concentrations were enhanced using a fed-batch strategy to concentrations as high as 28.7±1.1 mg/L, which was 40.3% higher as compared to the batch process.