High concentration and productivity of 1,3-propanediol from continuous fermentation of glycerol by Klebsiella pneumoniae

In a continuous fermentation of glycerol by Klebsiella pneumoniae, a final propanediol concentration of 35.2–48.5 g l−1 and a volumetric productivity of 4.9–8.8 g l−1 h−1 can be obtained at dilution rates between 0.1 and 0.25 h−1. These results correspond to about 80–96% of the theoretical maxima under ideal conditions (no ethanol and hydrogen formation). The highest propanediol concentration achieved in this study is close to teh maximum propanediol concentration (50–60 g l−1) found in batch and fed-batch cultures. The productivity of the continuous culture is, however, about 2–3.5-fold higher. Further improvement of the glycerol fermentation by K. pneumoniae should be focused on increasing the product tolerance of the strain and reducing the ethanol formation.