Miniprep

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Plasmid miniprep. 0.8% agarose gel ethidium bromide-stained.

A miniprep is a procedure to extract plasmid DNA from bacteria. It is based on the alkaline lysis method invented by the researchers Birnboim and Doly in 1979. The extracted plasmid DNA resulting from performing a miniprep is itself often called a "miniprep".

When bacteria are lysed under alkaline conditions both DNA and proteins are precipitated. After the addition of acetate-containing neutralization buffer the large and less supercoiled chromosomal DNA and proteins precipitate, but the small bacterial DNA plasmids can renature and stay in solution.

Minipreps are used in the process of molecular cloning to analyze bacterial clones. A typical plasmid DNA yield of a miniprep is 20 to 30 µg.