Xylose, the major component of lignocellulosic biomass, could not be naturally or efficiently utilized by most microorganisms. Xylose (co)utilization is considered a cornerstone of the efficient lignocellulosic-based biomanufacturing. We evolved a rapidly xylose utilizing strain Cev2-18-5, which showed the highest reported specific growth rate (0.357 h-1) on xylose among plasmid-free C. glutamicum strains. A genetically clear chassis strain CGS15 was correspondingly reconstructed with an efficient glucose-xylose co-utilization performance based on comparative genomic analysis and mutation reconstruction. With introducing a succinate-producing plasmid, the resulting strain CGS15-SA1 can efficiently produce 97.1 g/L of succinate with an average productivity of 8.09 g/L/h by simultaneously utilizing glucose and xylose from corn stalk hydrolysate. We further revealed a novel xylose regulatory mechanism mediated by the endogenous transcription factor IpsA with global regulatory effects on C. glutamicum. A synergistic effect on carbon metabolism and energy supply, motivated by three genomic mutations (Psod(C131T)-xylAB, Ptuf(Δ21)-araE and ipsAC331T), was found to endow C. glutamicum with the efficient xylose utilization and fast growth phenotype. Overall, this work not only provides promising C. glutamicum chassis strains for lignocellulosic biorefinery, but also enriches the understanding of xylose regulatory mechanism.

Global cellular metabolic rewiring adapts Corynebacterium glutamicum to efficient non-natural xylose utilization

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