Cost-effective melanin production using engineered Escherichia coli with autonomous tyrosine biosynthesis

Microbial melanin production traditionally relies on expensive tyrosine supplementation, making the cost-effective production of melanin challenging. To address this substrate dependency, we engineered an Escherichia coli strain capable of autonomous tyrosine synthesis through the co-overexpression of the tyrosine synthetase gene (aroG^fbr or tyrA^fbr with feedback resistance) and the tyrosinase gene tyr1. By further integrating the tyrosinase gene tyr1 into this engineered strain, we achieved melanin yields ranging from 5.58 to 7.57 mg/mL in the absence of exogenous tyrosine, thereby reducing production costs by 70 %–73.33 % compared to conventional methods that require exogenous tyrosine supplementation. This study establishes a robust and cost-effective platform for sustainable melanin production, with significant implications for the industrial manufacturing of microbial pigments.