Fig. 3
Systemic metabolic engineering of A. niger cell factory for citric acid production. A Learn-Design-Build-Test (LDBT) cycle combines multi-omics analysis, computational biology approaches, molecular genetic manipulation toolbox and high through-put platform to achieve customized metabolic engineering on a globe scale of A. niger. With the availability of massive multi-omics data of the industrial strains, including genome, transcriptome, proteome and metabolome, genome-scale metabolic modeling could integrate these data (Learn), quantitatively describe the phenotype, and predict the potential targets for metabolic engineering (Design). These targets would be fast verified and combined using the highly efficient genome editing system, and ultimately, obtaining a new generation of cell factories for citric acid production (Build). After detection using high throughput platform and optimization of fermentation processes, the new cell factories have the potential to be industrialized (Test)