From 2009.igem.org
Protocol for making competent cells (E.coli)
# 600 µl overnight (ON) Top10 E. coli culture is added to 60 ml Luria-Bertani (LB) medium.
# Grows at 37º C while being shaken until the optic density (OD550) is 0,2.
# Cool cells on ice.
# Harvest the cells in screwcap tubes (4 × 10 ml).
# Pour away the supernatant and keep the pellet on ice.
# Wash the cells with 10 ml cold 50mM CaCl2.
# The cells are being distributed in eppendorf tubes of 200 µl.
# Add 41.7 µl 87% glycerol and mix well.
# Store at -80 º C.
"
