Solid State Fermentation of Bacillus subtilis to Produce Menaquinone7 (Vitamin K2)

Abstract

Vitamins are required by organisms as vital nutrients in limited amounts as they cannot be synthesized in vivo. Many vitamins and related compounds are now industrially produced, and are widely used as food or feed additives, medical or therapeutic agents, complementary health products or cosmetics. The consumption of a particular form of vitamin K, namely Menaquinone 7 (MK7), as part of the diet shows a correlation with reduced risk of bone fractures and of some cardiovascular disorders. The concentration of MK7 in food products is low and, hence, there may be a benefit for supplementary MK7. MK7 production in Solid state fermentation (SSF) has received only limited attention in the open literature, in spite of natto production being hundreds of years old. The aim of this thesis is to assess the feasibility of enhancing the concentration of MK7 from SSF for the large scale production of a MK7 rich fermented food supplement. This process eliminates the expensive organic solvent extraction used to purify MK7, which is unlikely to be economical for animal vitamin production. Static and dynamic SSF for MK7 production were scaled up after initial screening studies. A novel, custom made concentric Rotating Drum Bioreactor (RDB) (3 kg) and packed bed fermenter (4 kg) were designed in house and fabricated for large scale studies. By using the scaled up RDB and packed bed reactor, MK7 production was scaled up from 10 g in bench scale to 4 kg. Mathematical models derived for the prediction of process variables will be important tools in the design and optimization of performance of large scale SSF bioreactors.

This study contributed appreciably to the understanding of the operation of RDBs and packed bed for MK7 production in SSF which are critical for further development of industrial level MK7 production.