Membrane and co-culture engineering for high-level curcumin production in Escherichia coli.

Curcuminoids, the major bioactive compounds of Curcuma longa, possess broad pharmacological activities including anticancer, antioxidant, and anti-inflammatory effects, making them valuable for pharmaceutical, nutraceutical, and cosmetic applications. Microbial biosynthesis provides a sustainable alternative. However, the efficiency remains limited due to the poor enzyme expression and the intrinsic hydrophobicity of curcuminoids, which causes intracellular accumulation and metabolic stress. Here, we develop a microbial platform that leverages chaperone-assisted enzyme folding, outer membrane vesicle (OMV)-mediated secretion, and modular co-culture engineering to enhance curcuminoid production in Escherichia coli. Co-expression of molecular chaperones improves the solubility and catalytic performance of plant-derived curcumin synthases, while the OMV system facilitates partial export of hydrophobic products, alleviating cellular burden. By dividing the biosynthetic pathway into upstream ferulic acid and downstream curcumin modules, and implementing carbon-source-based metabolic partitioning, we achieve a relatively stable co-culture, resulting in the production of 978 mg/L in 3 L fed-batch bioreactor, the highest titer reported to date. Our work establishes a versatile framework for microbial synthesis of hydrophobic natural products.