The filamentous fungusAspergillus nidulansproduces an α‐L‐rhamnosidase of potential oenological interest

The production of α- l-rhamnosidase by Aspergillus nidulans has been investigated. In the presence of rhamnose as sole carbon source, this fungus produces an α- l-rhamnosidase of molecular weight 90 kDa. Production of this enzyme is under carbon catabolite repression, apparently by a CreA-independent system. At acidic ambient pH there is an increase in the synthesis of the enzyme which is not related to PacC. Using ρ-nitrophenyl-α- l-rhamnopyranoside as substrate, the enzyme activity in culture filtrates shows pH and temperature optima of 4·5–8 and 40–50 °C, respectively. At the concentrations found in must or wine, enzyme activity was only slightly affected by glucose and SO2 and partly inhibited by ethanol, indicating a potential for use in wine aroma release.