Integrating Biofilm-Based Fermentation With Continuous Processes for Improved L-Valine Production

Abstract

L-valine, an essential branched-chain amino acid, is widely used across various industrial sectors. Despite its significance, there is a scarcity of continuous fermentation methodologies, specifically for L-valine production. Biofilm-based Technologies face challenges in sustaining continuous L-valine production due to cell wall damage caused by L-valine sterilization. Here, we combined continuous fermentation principles with Biofilm-based technologies to develop a biofilm-based continuous fermentation (BCF) system, enabling sustained L-valine production. By analyzing the fermentation kinetics of free-cell fermentation (FCF), we optimized the L-valine titer in BCF to 60–70 g/L, achieving a yield of 0.44 g/g glucose—a 10% increase over FCF. Notably, reducing the controlled L-valine titer in BCF extended the fermentation time but simultaneously decreased both the yield and production rate. Conversely, shortening the fermentation time was associated with an increase in both yield and production rate. In summary, BCF significantly improved L-valine purity, yield from glucose, and production rate while reducing by-product formation.