Background: l-Leucine is an important essential amino acid with multiple industrial applications, whose market requirements cannot be met because of the low productivity.
Main methods and major results: In this study, a strain of Corynebacterium glutamicum with high l-leucine yield was constructed to enhance its acetyl-CoA supply and glucose utilization. One copy of leuA under the control of a strong promoter was incorporated into the C. glutamicum genome. Then, acetyl-CoA supply was increased by the integration of a terminator in front of gltA and by the heterogeneous overexpression of acetyl-CoA synthetase (ACS) and deacetylase (CobB) derived from Escherichia coli. Next, the transcriptional regulator sugR was deleted to enhance glucose uptake via a phosphotransferase-mediated route. In fed-batch fermentation performed in a 5-L reactor, l-leucine production of 40.11 ± 0.73 g L-1 was achieved under the optimized conditions, with an l-leucine yield and productivity of 0.25 g g-1 glucose and 0.59 g L-1 h-1 , respectively.
Conclusions and implications: These results represent a significant improvement in the l-leucine production of C. glutamicum, indicating that the process possesses high potential for industrial application. These strategies can be also expanded to enable the production of other value-added biochemicals derived from the intermediates of central carbon metabolism.
Keywords: Corynebacterium glutamicum; acetyl-CoA supply; glucose utilization; l-leucine; metabolic engineering.
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