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.