Ferulic acid is converted by certain strains of yeast, notably strains used in brewing of wheat beers, such as Saccharomyces delbrueckii (Torulaspora_delbrueckii), to 4-vinyl guaiacol (2-methoxy-4-vinylphenol) which gives beers such as Weissbier and Wit their distinctive "clove" flavour. Saccharomyces cerevisiae (dry baker's yeast) and Pseudomonas fluorescens are also able to convert trans-ferulic acid into 2-methoxy-4-vinylphenol.[16] In P. fluorescens, a ferulic acid decarboxylase has been isolated.[17]