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 marine bacterium Roseovarius nubinhibens for efficient conversion of lignin-derived carbon into valuable chemicals with seawater as a water source. We created independency of the superior catalytic capacity of R. nubinhibens to circumvent a rare polar effect, and genetically decoupled the bioproduction pathway from central metabolism, channeling all lignin-derived carbon into desired products. Next, an orthogonal growth module was 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 identified a cross-module push-and-pull synergy between bioproduction and cell growth, enabling enhanced performance and robustness. By deploying this biological scheme, we successfully achieved escalated conversion of the lignin-derived monomer 4-hydroxybenzoate to value-added compounds protocatechuate and {beta}-ketoadipate with seawater, rather than freshwater, as the water source, generating a distinct blue biological scheme with potentials in simultaneous carbon and water conservation.