Construction of Corynebacterium glutamicum chassis for preferential utilization of xylose by adaptive laboratory evolution.

OBJECTIVES

To fully utilize lignocellulosic hydrolysate abundant in xylose content, it is necessary to engineer a Corynebacterium glutamicum strain that can preferentially and efficiently utilize xylose in the presence of glucose/xylose mixtures.

RESULTS

C. glutamicum strain CGS15X5-E2 was obtained through metabolic engineering and adaptive laboratory evolution (ALE), which preferentially utilizes xylose and completely consumes it before switching to glucose utilization. A genetically defined chassis strain, CGS15X57, was constructed to switch to glucose consumption only after xylose was depleted based on genome analysis and mutation reconstruction, in which xylose utilization capability was also enhanced. The average xylose consumption rate of CGS15X57 reached 0.833 ± 0.048 g/l/h, which was 28.0% higher than that of the control. Three new beneficial mutations (Cgl1992, Cgl2948 and Cgl2948) endow C. glutamicum with rapid growth and efficient xylose utilization phenotypes.

CONCLUSIONS

A chassis strain of C. glutamicum that preferentially and efficiently utilizes xylose has been obtained, facilitating the full utilization of lignocellulosic hydrolysates and the construction of co-culture systems under glucose/xylose mixed sugar conditions.