Repurposing the evolutionary fitness of marine bacteria for water-conserving conversion of lignin-derived carbon

Reverting waste carbon into chemicals and materials with minimal freshwater reliance is essential for a sustainable future. Here, we report the establishment of a blue biological scheme by repurposing the evolutionary fitness of the marine bacterium Roseovarius nubinhibens for efficient conversion of lignin-derived carbon into valuable chemicals with seawater as a water source. We create independency of the superior catalytic capacity of R. nubinhibens to circumvent a rare polar effect, and genetically decouple the bioproduction pathway from central metabolism, channeling all lignin-derived carbon into desired products. Next, an orthogonal growth module is generated with acetate as a second carbon source, which is a ubiquitous byproduct and inhibitor in plant biomass hydrolysis, to sustain cell growth and supply necessary resources, but not substrates, for the growth-coupled bioproduction. Besides this designed metabolic segregation, we identify a cross-module push-and-pull synergy between bioproduction and cell growth, enabling enhanced performance and robustness. By deploying this biological scheme, we successfully achieve escalated conversion of the lignin-derived monomer 4-hydroxybenzoate to value-added compounds protocatechuate and β-ketoadipate with seawater, rather than freshwater, as the water source, generating a distinct blue biological scheme with potential for simultaneous carbon and water conservation. Reverting waste carbon into chemicals with minimal freshwater use is essential for a sustainable future. Here, the authors engineer the marine bacterium R. nubinhibens, by decoupling bioproduction from central metabolism to convert lignin into chemicals with seawater as a water source.