Abstract: The yield of 1,3-propandiol （PDO）is a bottleneck of the industrial application of polytrimethylene-tereph-thalate （PTT）. In order to increase the titer of PDO, the influences of different carbon sources to the carbon fluxes and the transcription and activity of key enzyme DhaB during the biosynthesis of PDO by Klebsiella pneumonia ZG25 were studied. When using glucose as the sole carbon source, the biomass of K. pneumonia ZG25 was highest but the PDO was not detected in the medium. The PDO yield of K. pneumonia ZG25 by using glycerol as the sole carbon source achieved 9 g/L. Compared with the fermentation by using glycerol as the sole carbon source, the biomass and the yield of PDO were increased by 66.7% and 150% respectively, when 5 g/L glucose was applied as supplementary carbon source. Further analysis exhibited that the mRNA level of dhaB and the activity of DhaB were also increased by 20% and 64% respectively. These results suggest that the mixed carbon sources strategy activate the transcription of dhaB, enhance the activity of DhaB and strengthen the synthesis of PDO by K. pneumonia.

Key words: polytrimethylene tereph thalate, 1,3-propandiol, klebsiella pneumonia, carbon source, regulation