A protocol kindly provided to our team by the advisor to the 2018 MIT iGEM team (Dr. Brian Teague). It is modified slightly from that version (made by Stefan Maas in 1997) to fit our needs. Stefan Maas' protocol is similar to the Hanahan, D. protocol from 1983.It worked pretty well to make good competent cells in Summer 2018 and we just used it again in Summer 2019.