Rational reformation of Corynebacterium glutamicum for producing L-lysine by one-step fermentation from raw corn starch

This article focuses on engineering Corynebacterium glutamicum to produce L-lysine efficiently from starch using combined method of classical breeding and genome breeding. Firstly, a thermo-tolerable L-lysine-producing C. glutamicum strain KT45-6 was obtained after multi-round of acclimatization at high temperature. Then, amylolytic enzymes were introduced into strain KT45-6, and the resultant strains could use starch for cell growth and L-lysine production except the strain with expression of isoamylase. In addition, co-expression of amylolytic enzymes showed a good performance in starch degradation, cell growth and L-lysine production, especially co-expression of alpha-amylase (AA) and glucoamylase (GA). Moreover, L-lysine yield was increased by introducing AA-GA fusion protein (i.e., strain KT45-6S-5), and finally reached to 23.9 +/- 2.3 g/L in CgXII(IP)M-medium. It is the first report of an engineered L-lysine-producing strain with maximum starch utilization that may be used as workhorse for producing amino acid using starch as the main feedstock.

Automated summary

This study successfully engineered Corynebacterium glutamicum to efficiently produce L-lysine from starch using a combined method of classical breeding and genome breeding. By introducing amylolytic enzymes and co-expressing them, the production of L-lysine was significantly increased.