Enhanced production of a natural blue pigment indigoidine as sustainable fabric dyes using metabolically engineered Corynebacterium glutamicum

Abstract

Current industrial production of dyes for textiles involves the use of many toxic chemicals, which has caused severe water pollution. For this, indigoidine has gained attention as an alternative natural blue dye that would contribute to the sustainable textile industry. However, bio-based production of indigoidine needs to be further improved to compete with existing synthetic blue dyes. Here, we report a metabolically engineered Corynebacterium glutamicum that can produce indigoidine at high concentration and productivity. First, blue-pigment indigoidine synthetase (bpsA) gene from Streptomyces lavendulae was expressed in C. glutamicum, which carries strong fluxes toward L-glutamate, a precursor of indigoidine. Production performance of this base strain, already producing 7.3 ± 0.3 g/L indigoidine from flasks, was further enhanced by streamlining intracellular supply of the precursors L-glutamate and L-glutamine, strengthening phosphotransferase system-independent glucose uptake system, channeling carbon fluxes from glycolysis to tricarboxylic acid (TCA) cycle, and minimizing byproducts formation. The final strain named BIRU11 produced 49.30 g/L indigoidine with a productivity of 0.96 g/L/h from fed-batch fermentation, the highest titer and productivity to date. Finally, indigoidine from the fed-batch fermentation of the BIRU11 strain was utilized to dye white cotton fabrics to examine its color and performance. Our study demonstrates the potential sustainable production of fabric dyes by using a metabolically engineered bacterium.