Add 50 µl carrier DNA to a 1.5 ml tube.
scrap cells from plate and add to the carrier DNA.
Add in the following order:
1-2 µl DNA-plasmid (up to 30-50 µl)
240 µl PEG (50%)
36 µl Li-Ac (1M)
resuspend with blue tip
incubate at 30°C or RT at least 30 min
heat shock: 45°C, 15 min (or 42°C for 20 min)
spin down, resuspend in 100μl H2O and plate everything on corresponding medium
Plasmid: 100 ng - 1 µg
carrier DNA: salmon/herring sperm DNA in H2O, 2mg/ml stock, 500 µl aliquots, heat-inactivated at 95°C for 5-6 min and put on ice before use (has to be done once).
50% poly-ethylen-glycol (PEG) (MW 3''350) solution, filter-sterilized
1M Li-Acetate, autoclaved