Continuous bioproduction of 1,3‐propanediol from biodiesel raw glycerol: Operation with free and immobilized cells of Clostridium butyricum DSM 10702

Abstract

AbstractThis work investigates the bioproduction of 1,3‐propanediol (1,3‐PD) from biodiesel derived raw glycerol with free and immobilized cells of Clostridium butyricum DSMZ 10702. The cultures were carried out under continuous conditions in a stirred tank bioreactor with suspended cells and a fluidized‐bed bioreactor with immobilized cells. The microorganisms were immobilized by entrapment in calcium alginate gel beads. The effect of dilution rate and glycerol concentration in the feed on 1,3‐PD production was investigated for both bioreactor configurations. Results showed that 1,3‐PD concentration and glycerol uptake decreased when dilution rate increased. Maximum product concentration was similar in both bioreactors, 24.3 g/L and 20.5 g/L for suspended cells and Ca‐alginate immobilized cells, respectively, for a glycerol feed concentration of 50 g/L and a dilution rate of 0.05 h−1. The higher productivities were observed for a dilution rate of 0.15 h−1 for the suspended culture bioreactor and 0.2 h−1 for the immobilized cell bioreactor. Although maximum productivity was similar in both systems, 2.8 g 1,3‐PD/(L · h), cell immobilization was shown to be more resistant to washout at higher dilution rates.