Plasmids are extrachromosomal DNA molecules naturally found in bacteria and archaea. In genetic engineering, they are used as cloning vectors due to their ability to replicate independently of the host genome. This feature allows plasmids to be introduced in vitro into different cells, enabling the expression of specific genes.

Their use has proven highly effective in biomedical research, pharmaceutical production, and agricultural biotechnology. In all these fields, extracting plasmid DNA is the first necessary step before further manipulation and analysis.

Plasmid DNA extraction protocol

To isolate plasmid DNA from its host cell, the following sequential protocol is used:

1. Cell lysis: Cells are incubated overnight with a lysis buffer to break the bacterial cell wall and release the intracellular contents.
2. Initial washes: Centrifugation at 2,500 xg for 10 minutes is performed using a microcentrifuge. The supernatant is discarded, and the pellet contains the plasmids of interest.
3. Successive treatments: The pellet is incubated with various reagents such as enzymatic solutions, SDS, isopropanol, and phenol/chloroform. These steps are alternated with centrifugations at 18,500 xg for 15 minutes to separate chromosomal and plasmid DNA from other cellular components.
4. Specific isolation: Magnetic beads or other methods are used to purify plasmid DNA.
5. Storage: The purified plasmid DNA is resuspended in a storage solution and kept at 4 °C for later use.

The Biocen 22 microcentrifuge is well-suited for these applications, offering a wide range of speeds and the versatility needed for the different stages of the protocol.

Relevance of plasmid DNA in biotechnological production

The use of plasmids in cellular cloning has completely revolutionized medicine, enabling the production of large quantities of active pharmaceutical ingredients through the genetic modification of producing cells. For this reason, the use of an appropriate protocol and the correct tools to carry it out, such as centrifuges, is of great importance and is now commonplace in most laboratories dedicated to this purpose.