Enhanced 1,3-propanediol production by supply of organic acids and repeated fed-batch culture.

In fed-batch culture of Klebsiella pneumoniae, 1,3-propanediol production was growth associated, while the by-products, including lactic acid and ethanol, increased sharply as the cells grew slowly. When the fed-batch culture was supplied with a mixture of organic acids including citrate, fumarate and succinate, cell growth and 1,3-propanediol production increased significantly, whereas the by-products, especially lactic acid and ethanol, decreased sharply. High concentrations of PDO and acetate inhibited cell growth and PDO production. To improve the PDO production, repeated fed-batch culture with addition of the organic acid mixture was performed in a 5-l reactor. The fed-batch culture was repeated five times, and the 1,3-propanediol yield and concentration reached above 0.61 mol mol(-1) and 66 g l(-1), respectively, in 20 h for each cycle. Furthermore, the PDO productivity reached above 3.30 g l(-1) h(-1) in each cycle, which was much higher than that of the original fed-batch culture.