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Purifying plasmid DNA from bacterial cultures

Today in the lab I was doing a miniprep experiment. This experiment allows the purification of plasmid DNA from bacterial cultures. The previous day, I prepared overnight cultures of bacteria that I had previously transformed with a vector plasmid that contains a human gene which I will be using for my future experiments. The bacteria multiplied overnight and produced multiple copies of the gene. Today, I extracted from these bacteria the plasmid DNA that contains the gene.

Timelapse: Preparing the bacterial samples for plasmid DNA extraction.

Detailed methods of today’s experiment

Today, the bacteria were lysed under alkaline conditions, and this caused chromosomal DNA and proteins to be denatured. The plasmid DNA containing the inserted human gene remained stable. This method is called a miniprep because the isolation of plasmid DNA is rapid and small-scale. It yields around 50-100 μg of plasmid DNA from each bacterial culture.