Propionic acid production in an in situ cell retention bioreactor

Abstract.

Continuous fermentations were conducted with in situ cell retention using spin filters (pore size 5 µm and 10 µm) for propionic acid production by Propionibacterium acidipropionici. Continuous fermentation with a 5-µm pore size spin filter resulted in 50% cell retention. Propionic acid productivity was enhanced (0.9 g l^–1 h^–1) by approximately four-fold compared to conventional batch fermentation (0.25 g l^–1 h^–1). The in situ cell retention (5-µm pore size spin filter) bioreactor was operated continuously and smoothly for 8 days at a dilution rate of D=0.05 h^–1.