Summary The catabolic fate of the major monomeric sugar of red macroalgae, 3,6‐anhydro‐ L ‐galactose ( AHG ), is completely unknown in any organisms. AHG is not catabolized by ordinary fermentative microorganisms, and it hampers the utilization of red macroalgae as renewable biomass for biofuel and chemical production. In this study, metabolite and transcriptomic analyses of V ibrio sp., a marine bacterium capable of cataboliz...