Frozen competent yeast cells that can be transformed with high efficiency using the LiAc/SS carrier DNA/PEG method.

Here we describe a protocol for the production of frozen competent yeast cells that can be transformed with high efficiency using the lithium acetate/single-stranded carrier DNA/PEG method. This protocol allows the production of highly competent yeast cells that can be frozen and used at a later date and is especially useful for laboratories using one or two strains repeatedly. The production of yeast cells for freezing takes only approximately 30 min, once the yeast culture has grown up. Transformation with frozen competent yeast cells will take approximately 30 min, depending on the heat shock used.