Scaling up biofilm bioreactors for enhanced menaquinone-7 production

Area of Science:

• Biotechnology
• Biochemical Engineering
• Microbial Fermentation

Background:

• Menaquinone-7 (MK-7) is a vital nutrient with established health benefits.
• Current MK-7 production relies on fermentation, with scalability challenges.
• Biofilm reactors offer a novel approach for enhanced microbial product synthesis.

Purpose of the Study:

• To scale up an innovative Bacillus subtilis natto biofilm reactor from 2-L to 30-L.
• To evaluate the impact of scaling parameters (kLa, P/V, Vtip) on MK-7 production.
• To investigate fed-batch strategies for further enhancing MK-7 yields.

Main Methods:

• Utilized a 30-L pilot-scale biofilm bioreactor with Bacillus subtilis natto.
• Evaluated three scale-up strategies: maintaining volumetric oxygen mass transfer coefficient (kLa), agitation power input per unit volume (P/V), and impeller tip velocity (Vtip).
• Implemented fed-batch glucose addition to the base media.

Main Results:

• The kLa constant method proved most effective for scaling, achieving 21.0 ± 1.0 mg/L MK-7.
• Fed-batch glucose addition significantly increased MK-7 concentration to 28.7 ± 0.3 mg/L.
• This represents a 2.3-fold increase compared to suspended-cell bioreactors.

Conclusions:

• The biofilm bioreactor technology is scalable for commercial MK-7 production.
• Fed-batch strategies in biofilm reactors offer a significant advantage over traditional fermentation.
• Biofilm reactors show promise as a replacement for static fermentation methods.