SECTION 8-4 - Plasmid “Mini-Prep” Method

Abstract

This chapter explains the plasmid mini-prep method, which is useful for preparing partially purified plasmid DNA in small quantities from a number of transformants. It relies on an alkaline SDS lysis to free the plasmid DNA from the cell, leaving behind the E. coli chromosomal DNA with a cell-wall debris. After the solution is cleared of the cell-wall debris, the supernatant is retained. Plasmid DNA is then purified from the supernatant along with substantial qualities of E. coli DNA. The mini-prep method provides enough partially purified plasmid DNA for a rapid analytical restriction digest analysis of plasmids before large-scale growth. The method can also be used when a small amount of plasmid DNA rather than large amounts of plasmid DNA are required. The time required to carry out the procedure is two hours. A bacterial colony is selected in advance. A colony with sterile loop is removed and is placed in 20 ml of LB medium. It is then grown at 37°C until culture is saturated.