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Bacterial Transformation

Bacterial Transformation

In 1928, bacteriologist Frederick Griffith worked on a vaccine for pneumonia, which is caused by Streptococcus pneumoniae bacteria. Griffith studied two pneumonia strains in mice: one pathogenic and one non-pathogenic. Only the pathogenic strain killed host mice.Griffith made an unexpected discovery when he killed the pathogenic strain and mixed its remains with the live, non-pathogenic strain. Not only did the mixture kill host mice, but it also contained living pathogenic bacteria that...

Transformation

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Microbial communities are dynamic environments where cell lysis releases free DNA into the surroundings. Other cells can take up this extracellular DNA through a process known as transformation.When a cell incorporates this foreign DNA into its genome, resulting in genetic modification, the process is known as transformation. Cells capable of this process are termed competent. Competence can be natural, as observed in certain bacteria and archaea, or artificially induced in the...

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Related Experiment Video

Updated: Jul 7, 2026

Mapping Bacterial Functional Networks and Pathways in Escherichia Coli using Synthetic Genetic Arrays

Mapping Bacterial Functional Networks and Pathways in Escherichia Coli using Synthetic Genetic Arrays

Published on: November 12, 2012

Microwave improved Escherichia coli transformation.

R Fregel¹, V Rodríguez, V M Cabrera

¹Department of Genetics, University of La Laguna, Tenerife, Canary Islands, Spain. rfregel@ull.es

Letters in Applied Microbiology

|February 21, 2008

Summary

Microwave pulses can triple the efficiency of calcium chloride chemical transformation in Escherichia coli. Combining this with heat shock further boosts transformation rates, offering a cost-effective alternative for labs lacking electroporation equipment.

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Last Updated: Jul 7, 2026

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Electroporation of Mycobacteria

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Published on: May 23, 2008

Area of Science:

Molecular Biology
Microbiology

Background:

Calcium chloride chemical transformation is a widely used method for cloning in Escherichia coli, especially in smaller laboratories.
Improving the efficiency of this transformation technique is of significant interest to researchers.

Purpose of the Study:

To investigate practical improvements in the transformation efficiency of Escherichia coli using calcium chloride.
To explore the use of microwave pulses as an alternative to the traditional heat-shock step.

Main Methods:

Competent Escherichia coli cells were treated with a 1-minute microwave pulse at 180W.
A sequential treatment involving heat shock, incubation on ice, and a microwave pulse was also tested.
Transformation efficiency was measured and compared to the classical heat-shock method.

Main Results:

A 1-minute microwave pulse increased transformation efficiency approximately threefold (3.3 +/- 0.5) compared to the standard heat shock.
A combined treatment (heat shock - ice - microwave pulse) resulted in an additional 1.6-fold increase.
The overall increase in transformation efficiency using the combined method was approximately 5.3-fold.

Conclusions:

The microwave pulse method significantly enhances classical heat shock treatment for bacterial transformation.
This technique offers a valuable and potentially more affordable alternative to electroporation for laboratories with limited resources.