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 the 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. (C) 1997 by Elsevier Science Inc.