Pulse Field Gel Electrophoresis

Abstract

Pulse Field Gel Electrophoresis (PFGE) is a powerful genotyping technique used for the separation of large DNA molecules (entire genomic DNA) after digesting it with unique restriction enzymes and applying to a gel matrix under the electric field that periodically changes direction. PFGE is a variation of agarose gel electrophoresis that permits analysis of bacterial DNA fragments over an order of magnitude larger than that with conventional restriction enzyme analysis. It provides a good representation of the entire bacterial chromosome in a single gel with a highly reproducible restriction profile, providing clearly distinct and well-resolved DNA fragments.

Keywords: Genomic DNA; Genotyping technique; Pulse field gel electrophoresis; Restriction enzyme.

Fig. 1

An example comparison of PFGE versus conventional electrophoresis. In both cases, the gel (grey rectangle) is placed in a buffer inside a gel rig with anodes (+) and cathodes (−) (top diagrams). In the case of PFGE, the direction of current cycles between 1, 2, and 3. As depicted in the bottom graphs, unlike conventional electrophoresis where current only runs in a single direction, PFGE cycles between several directions, allowing for separation of large molecular weight DNA

Fig. 2

A representative processed gel showing the different banding patterns of eight USA types. Image is a negative image of a processed gel with higher molecular weight (MW) DNA towards top of the image