In order to allow E. coli to produce GFP protein, genetic engineering has to be carried out to insert the GFP gene into E. coli cells. In order for this to be done the GFP gene has to be first introduced into vectors which will then be incorporated into E.coli.
In this case, the vector used are small circular DNA molecules that replicate independently of the genome called plasmids. The plasmids used have been modified to function as vectors, often containing a seletable biomarker gene as such that of antibiotic resistance (eg. Ampicillin resistance) apart from the gene of interest to be introduced. The biomarker gene serves an important role of allowing successfully transformed bacteria to be selected from the unsuccessful ones. 
The plasmid used to create transformed E.coli which were used in our fermentation experiment is Biorad’s pGLO plasmid which contains a biomarker gene for ampicillin resistance and a gene coding for the green fluorescent protein. The pGLO also incorporates a gene regulatory system, which activates transcription of GFP in the pressence of the sugar, arabinose.
The pGLO can be introduced into E. coli by a variety of transformation methods. One of these methods is by using calcium chloride. E. coli cells and pGLO are treated with a weak solution of calcium chloride under low temperatures. The positively charged calcium ions are thought to bind to the negatively charged cell wall and allow the pGLO plasmid to adsorb onto the bacteria surface. The E. coli and pGLO are then heat shocked to allow the pGLO to enter E. coli causing it to become transformed.
The pGLO can be introduced into E. coli by a variety of transformation methods. One of these methods is by using calcium chloride. E. coli cells and pGLO are treated with a weak solution of calcium chloride under low temperatures. The positively charged calcium ions are thought to bind to the negatively charged cell wall and allow the pGLO plasmid to adsorb onto the bacteria surface. The E. coli and pGLO are then heat shocked to allow the pGLO to enter E. coli causing it to become transformed.
Since the pGLO plasmid contains both the regulatory sequence together with the GFP gene and the gene for ampicillin resistance, sucessful transformants can be selected by growing these E. coli cells on LB agar containing ampicillin and arabinose. Sucessful transformants will be able to grow on the agar plate and transformants containing the GFP gene will be able to express GFP due to the pressence of Arabinose.
References
- http://iiumedic.com/web/v1/wp-content/uploads/2009/08/5-bactransformation.pdf
- http://www.clt.astate.edu/agrippo/fall2005lab7pGLO%20Transformation.doc
- http://whyfiles.org/246e_coli/images/e_coli.jpg
- http://orgchem.colorado.edu/hndbksupport/drying/images/decant.jpg
- http://cba.mit.edu/docs/04.05.NSF/images/green.jpg
- http://www.cvgs.k12.va.us/research/Final/sresch06/arrington/pglomap_resized.jpg
- http://unlmbsc.files.wordpress.com/2007/11/pglo-for-blog.jpg
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