4. Conclusions
CRISPR-Cpf1 genome editing system
is an efficient recombination technology to generate knock-out mutants
of the lactate dehydrogenase 1 gene to enhance succinic acid production.
The ΔldhA-6 mutant produced 14.82 g L-1succinic acid production over 6 h, equating to a 2.47 g
L-1 h-1 productivity in the
fermentation of 4% hydrolysate, with an 86.2% glucose and 20% xylose
consumption. Under the same fermentation conditions, the transformant
[Psod:sucE- ΔldhA ] showed a productivity of 2.95 g
L-1 h-1 and produced approximately
39.67 g L-1 succinic acid over 48 h in the fed-batch
process. The yield of succinic acid from the hydrolysate when only
considering glucose consumption during the fed-batch fermentation is
approximately 84.4%. Xylose consumption was slower than glucose and
still remained throughout the fermentation. By diminishing the sugar
loss during enzymatic hydrolysis and the fermentation processes, the
production of succinic acid will likely be enhanced in the future.