HSP12 is essential for biofilm formation by a Sardinian wine strain of S. cerevisiae

Sardinian sherry strains of S. cerevisiae form a biofilm on the surface of wine at the end of the ethanolic fermentation, when grape sugar is depleted and when further growth becomes dependent on access to oxygen. A point mutation in HSP12 or deletion of the entire gene results in inability to form this film. HSP12 encodes a heat‐shock protein previously foundby others to be active during stationary phase, in cells depleted for glucose, and in cells metabolizing ethanol and fatty acids, all conditions associated with sherry biofilms. The DNA sequence of HSP12 allele of strain Ar5‐H12 has GenBank Accession No. AY046957.