Plant-derived lignans, consumed daily by most individuals, are thought to protect against cancer and other diseases 1 ; however, their bioactivity requires gut bacterial conversion to enterolignans 2. Here, we dissect a four-species bacterial consortium sufficient for all five reactions in this pathway. A single enzyme (benzyl ether reductase; ber), was sufficient for the first two biotransformations, variable between strains of Eggerthella lenta, critical for enterolignan Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: