Programmable marine bacteria catalyze the valorization of lignin monomers

Efficiently converting lignin, the second most abundant biopolymer on Earth, into valuable chemicals is pivotal for a circular economy and net-zero future. However, lignin is recalcitrant to bio-upcycling, demanding innovative solutions. We report here the biological valorization of lignin-derived aromatic carbon to value-added chemicals without requesting extra organic carbon and freshwater via reprogramming the marine Roseobacter clade bacterium Roseovarius nubinhibens . We discovered the unusual catalytic advantages of this strain for the oxidation of lignin monomers and implemented a CRISPR interference (CRISPRi) system with the lacI -P trc inducible module, nuclease-deactivated Cas9, and programmable gRNAs. This enabled precise and efficient repression of target genes. By deploying the customized CRISPRi, we reprogrammed the carbon flux from a lignin monomer, 4-hydroxybenzoate, to achieve maximum production of protocatechuate, a pharmaceutical compound, while maintaining essential carbon for cell growth and biocatalysis. As a result, we achieved a 4.89-fold increase in protocatechuate yield with a dual-targeting CRISPRi system. Our study introduces a new-to-the-field lineage of marine bacteria and underscores the potential of blue biotechnology leveraging resources from the ocean for simultaneous carbon and water conservation.