Combinatorial metabolic engineering of Escherichia coli to efficiently produce L-threonine from untreated cane molasses.

BACKGROUND

The industrial production of L-threonine faces challenges because of high production costs, especially those of substrates, meaning new production methods are needed.

METHODS

Fur, a new global transcription factor related to L-threonine biosynthesis, was discovered in this study. Multidimensional regulation combined with global transcriptional machinery engineering was used to modify an Escherichia coli strain.

RESULTS

The most efficient mutant showed high titer (154.2 g/L), productivity (2.14 g/L/h), and yield (0.76 g/g) of L-threonine production. These three parameters indicated that these engineering strategies were economically feasible for developing high L-threonine-producing strains. We integrated the sucrose utilization gene cluster into the genome to further reduce the production cost of L-threonine. Using untreated cane molasses as the substrate, L-threonine was successfully produced with a titer of 92.46 g/L and a cost reduction of 48 %.

CONCLUSION

This research offers advantages for industrial scalability, and the resulting engineered bacterium holds significant industrial application potential.