Succinic acid is a platform chemical with
potential for bio-based synthesis. However, the production
of bio-based succinate is limited because of insufficient
succinate efflux capacity in the late stage of fermentation.
In the present study, three different transporters, which
have been reported to be responsible for C4-dicarboxylates
transport, were employed for investigation of the transport
capacity of succinate in Escherichia coli. After engineered
strains were constructed, the fermentative production of
succinic acid was studied in serum bottles and 3 L of
fermentor. The results demonstrated that engineered strain
showed better efflux capacity than control strain under high
concentration of succinate. The ... More
Succinic acid is a platform chemical with
potential for bio-based synthesis. However, the production
of bio-based succinate is limited because of insufficient
succinate efflux capacity in the late stage of fermentation.
In the present study, three different transporters, which
have been reported to be responsible for C4-dicarboxylates
transport, were employed for investigation of the transport
capacity of succinate in Escherichia coli. After engineered
strains were constructed, the fermentative production of
succinic acid was studied in serum bottles and 3 L of
fermentor. The results demonstrated that engineered strain
showed better efflux capacity than control strain under high
concentration of succinate. The highest production of
succinate was 68.66 g/L, while the NCgl2130 transporter
may be the best candidate for succinate export in E. coli.
Further research showed that the expression levels and
relative enzyme activities involved in the metabolic pathway
all increased markedly, and the maximum activities of
PPC, PCK, PYK, and MDH increased by 1.50, 1.38, 1.28,
and 1.27-fold in recombinant E. coli AFP111/pTrc99aNCgl2130,
respectively. Moreover, the maximum level of
intracellular ATP increased by 23.79% in E. coli AFP111/
pTrc99a-NCgl2130. Taken together, these findings indicated
that engineered transporters can improve succinate production
by increasing key enzyme activities and intracellular ATP
levels. To the best of thew authors’ knowledge, this is the
first report on a mechanism to improve succinate production
by engineered transporters. This strategy set up a foundation
for improving the biosynthesis of other C4-dicarboxylates,
such as fumaric acid and malic acid.
