Influence of (+)-catechin on biofilm growth of oenological Saccharomyces cerevisiae strains

Background and aims: The ability of Saccharomyces cerevisiae to grow as a biofilm is characterised by the phenotypic feature of ‘Mat’ colony formation. This is regulated by the FLO gene family, and is hypothesised to allow attachment and community growth of S. cerevisiae. This study aims to investigate how biofilm growth by natural strains of S. cerevisiae isolated from grapes and musts is affected by anthocyanins present in grapes. Methods: Forty-six oenological S. cerevisiae strains were tested for their ability to form biofilms in the presence of the wine phenolic compound (+)-catechin. Overnight yeast cultures (0.1 μL) were inoculated in the centre of both soft agar plates (1% yeast extract, 2% peptone, 2% glucose, 0.3% agar) and soft agar plates supplemented with 100 mg/L of (+)-catechin, and incubated at 25 °C for 13 days. The plates were photographed after 3, 5, 7, 10 and 13 days. Photographs were analysed using ArchiCAD 8.1 to determine area growth as cm2. Results: Differences in mat structures were observed amongst the strains; ranging from a rough external texture with central hub and radial spokes to smooth in texture and entire in shape. When supplemented with (+)-catechin Mat formation and structure was changed; indicating anthocyanins can indeed change the growth behaviour of yeast strains. In some cases, the presence of (+)-catechin induced a transition to pseudohyphal growth within the colony. Conclusions: This work has highlighted variability amongst natural isolates of oenological yeast which needs to be explored further.