A research team analyzed the regulatory mechanisms of carbohydrate-hydrolyzing enzyme production in Aspergillus aculeatus, a filamentous fungus that produces enzymes with an excellent ability to degrade plant biomass. The team found that UDP-glucose 4-epimerase (Uge5), an enzyme known for its involvement in galactose metabolism, also regulates the expression of degrading enzyme genes in A. aculeatus. This is the very first report of Uge5’s roles in selective gene expression in response to different types of inducing sugars in filamentous fungi.