Flocculation Assay: Utilization of TRAC to Monitor Yeast Flocculation-Related Gene Expression

摘要

TRAC (transcript analysis with the aid of affinity capture) is an accurate, rapid, and economic method that has been developed at the VTT Technical Research Centre of Finland to follow the expression levels of a targeted group of genes. The method canbe applied to yeast lysates without purification of RNA. Most of the sample handling is conducted automatically using a 96-well format. Each sample is tested with pools each containing 20 to 30 gene-specific probes. At present, results can be obtained within two or three hours, but further improvements are expected. TRAC is cheap enough that wort fermentations can be sampled up to 10 times a day. This reveals very dynamic patterns of changes in gene expression especially during the first two days of wort fermentations. Results suggest that changes in gene expression may be more informative than instantaneous levels. Changes in expression of target genes, including genes involved in flocculation, clearly precede their physiological effects, so that TRAC has the potential to predict both the course of fermentation, including yeast flocculation and sedimentation, and the quality of the resulting yeast crop.