Curing Industrial Saccharomyces Yeasts of Parasitic 2μm Plasmid

Abstract

The 2μm circle plasmid is a parasitic DNA molecule found in laboratory Saccharomyces cerevisiae yeast. Our survey showed that most industrial Saccharomyces yeasts also contain 2μm DNA. A chimeric vector containing yeast SMR1 dominant resistance selectable marker cloned into native 2μm was used to cure endogenous 2μm DNA from yeast strains of baking, brewing, wine, and distilling origin. Competition tests with baker's yeast strain ATCC 7754 clearly demonstrated that 2μm DNA-free ([cir°]) derivatives conferred a growth advantage over their isogenic [cir⁺] cells. The 2μm-curing technology has a direct application to commercial food and beverage yeasts for enhanced growth efficiency. In addition, industrial [cir°] are attractive candidates for recombinant DNA-based pharmaceutical production.

• Competition test
• Industrial yeast
• Selfish DNA
• Southern analysis
• Transformation
• 2μm plasmid