McClean:Making and Using Frozen Yeast Competant Cells

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The following is a protocol to freeze down and use any of our S. cerevisae strains for standard LiOAc transformation at a later date. This is especially useful when you often need to perform many transformations using a single background strain. Adapted from the protocol by Geitz et. al 2007, Nature Protocols.


  • 50 mL Conical Tubes
  • Frozen Competant Cell Solution (recipe to follow)
  • Liquid YPD media (From media facility, or recipe in Amberg et. al's Methods in Yeast Genetics)
  • 100 well styrofoam freezer racks (that will fit standard 1.5 mL 'minifuge' tubes
  • A 250 mL sterile culture flask for each strain
  • A 2 L sterile flask for each strain

Stock Solutions

Frozen Competant Cell (FCC) Solution

Solution is 5% (v/v) glycerol and 10% (v/v)DMSO. Be sure to filter-sterilize.

Cell Preparation


Please feel free to post comments, questions, or improvements to this protocol. Happy to have your input!

  1. List troubleshooting tips here.
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Gietz, R.D. and R.A. Woods. (2002) TRANSFORMATION OF YEAST BY THE Liac/SS CARRIER DNA/PEG METHOD. Methods in Enzymology 350: 87-96.


or instead, discuss this protocol.