"One-step" buffer:

• 0.2 N lithium acetate
• 40% polyethylene glycol 3350
• 100 mM dithiothreitol
• pH 5.0

1. Grow 3-5ml overnight culture of yeast strain to be transformed, preferably in rich media such as YpD (1% yeast extract, 2% bactopeptone, 2% dextrose).
2. Next day, aliquot 5x10⁷ cells (OD600 of 1.0 = 1x10⁷ cells/ml) into an eppendorf tube and spin down. Use 5x10⁷ cells for each transformation.
3. To the pellet, add 50 ng-1 µg of plasmid DNA, 50 µg of single-stranded carrier DNA ( we use boiled salmon sperm DNA), and bring total volume to 100 µl with "One-step" buffer.
4. Incubate 30-60 minutes at 45°C and plate on appropriate selection media. Though we have had success transforming at 42-48°C, we find that 45°C is the optimal transformation temperature.
5. Incubate transformation plates at 30°C for 3-4 days

1. The DTT is very important, with 100 mM being optimal.
2. The transformation efficiency is 10⁴ transformants/ug plasmid DNA.
3. The above transformation efficiency does vary depending on the plasmid and the number of cells used.

Chen D-C, Yang B-C, Kuo T-T. One-step transformation of yeast in stationary phase. Current Genetics (1992) 21:83-84.