The present disclosure provides for an expression system for the production of blue pigment indigoidine. The system comprises a heterologous host cell, a DNA sequence encoding a Sc-IndB protein, and a DNA sequence encoding a Sc-IndC protein. The system may be configured for the co-expression of the Sc-IndB and Sc-IndC. DNA sequences encoding the Sc-IndB and Sc-IndC may be provided on at least one vector. Alternatively, the DNA sequences encoding the Sc-IndB and Sc-IndC may optionally be integrated into the genome of the heterologous host genome. The expression system may further comprise a sfp gene or a PPTase.