Abstract
The demand for 1,3-propanediol (1,3-PDO) has increased sharply due to
its role as a monomer for the synthesis of polytrimethylene
terephthalate (PTT). Although Clostridium butyricum is considered
to be one of the most promising bio-producers for 1,3-PDO, its low
productivity hinders its application on industrial scale because of the
longer time needed for anaerobic cultivation. In this study, an
excellent mutant of C. butyricum (DL07) was obtained with
high-level titer and productivity of 1,3-PDO, i.e. 104.78 g/L and 3.38
g/(L•h) vs. 94.23 g/L and 3.04 g/(L•h) using pure or crude glycerol as
substrate in fed-batch fermentation, respectively. Furthermore, a novel
sequential fed-batch fermentation was investigated, in which the next
bioreactor was inoculated by C. butyricum DL07 cells growing at
exponential phase in the prior bioreactor. It could run steadily for at
least eight cycles. The average concentration of 1,3-PDO in eight cycles
was 84.62 g/L with the average productivity of 3.05 g/(L•h). The
sequential fed-batch fermentation could achieve semi-continuous
production of 1,3-PDO with higher productivity than repeated fed-batch
fermentation, and would greatly contribute to the industrial production
of 1,3-propanediol by C. butyricum. Key words:
1,3-Propanediol; glycerol; Clostridium butyricum; sequential
fed-batch fermentation