Easy Transformation of Escherichia coli: Nanoparticle-Mediated Transformation

In this protocol, a colloidal solution containing mineral nanofibers is mixed with Escherichia coli and plasmid DNA and plated immediately on the appropriate selective plates. Sliding frictional forces, created when the bacteria are spread with a polystyrene stir stick across the surface of the agar, may result in penetration of the bacteria by the mineral fibers with its adherent cargo of DNA. The number of transformants increases during the first 60 sec of exposure to the mineral fiber:DNA complex and then reaches a plateau of ∼1 × 10⁶ to 2 × 10⁶ transformants/milligrams of DNA. Although not highly efficient, the method is very simple.