2μm DNA PLASMID IN BREWERY YEASTS

Using an agarose gel screening procedure, 2 μm DNA plasmid was detected in all of 10 brewing strains of Saccharomyces yeast examined and in both of two non-brewing, dextrin-utilising strains. Plasmid DNA was identified in yeast grown with access to air in MYGP medium or in hopped wort, and in yeast harvested from 3-day wort fermentations. The yeast plasmid is a suitable self-cloning vector for the genetic manipulation of brewing yeasts by transformation.