Single nucleotide polymorphisms and transcription analysis of genes involved in ferulic acid decarboxylation among different beer yeasts

The compound 4-vinylguaiacol, which is produced by the decarboxylation of ferulic acid in certain yeasts, is an important flavour compound in the brewing industry. This decarboxylation ability varies significantly in different beer yeasts and most strains possessing this ability are classified as ale yeasts. In this study, both lager and ale strains were used for fermentation tests and the decarboxylation ability was quantified. Two lager and three ale strains were identified with high ferulic acid decarboxylation activity. Single nucleotide polymorphism (SNP) analysis of PAD1 and FDC1 was conducted by gene sequencing and alignment. In addition, transcription analysis of the two genes was also performed with a GeXP genetic analysis system. A positive relationship between SNPs and ferulic acid decarboxylation activity was determined, and the premature termination codon introduced by base substitution and insertion resulted in the loss of this ability in beer yeasts, whereas other SNPs had a relatively limited influence on it. The GeXP results revealed that genes containing nonsense mutations exhibited low transcription levels, which could be explained by nonsense-mediated mRNA decay. These findings will further the understanding of the relationship between SNPs and biological traits, and will hopefully provide a promising strain selection method for industrial yeasts based on SNP markers. Copyright © 2015 The Institute of Brewing & Distilling