Safety considerations of E.coli DHα

Most E.coli strains are harmless and are a normal part of human gut flora, however, environmental strains such as serotype O157:H7, can cause serious food poisoning in humans. The genetic set up of the E.coli laboratory strain DH5α has been engineered in such a way, that these strains can be considered as safe laboratory strains, if standard safety protocols are followed.

The genetic characteristics of the DH5α strains are:

F- endA1 glnV44 thi-1 recA1 relA1 gyrA96 deoR nupG Φ80dlacZΔM15 Δ(lacZYA-argF)U169, hsdR17(rK- mK+), λ–

Amongst the most important genetic modifications is F-, which denotes the strain´s inability to develop F-pili. This prevents transfer of genetic information by horizontal gene transfer. Another important genetic modification is recA1, making the DH5α strain recombination deficient, so the mutant gene prevents recombination of the plasmid into the E.coli genome so that the plasmid inserts are more stable. This leaves DH5α also very sensitive to UV-light as a result of the strains inability to undergo recombination, thereby impairing its DNA repair mechanism.

Local biosafety group

We have a local biosafety group at our institution, and they have advised us to follow standard safety protocols for genetic engineering and molecular biology that are the standard practice at our institution. None of the BioBricks submitted in this project comprise any elevated danger of researcher safety, public safety, or environmental safety, if the standard practice is followed.

References

• Woodcock, D.M. et al. (1989) Nucl. Acids Res., 17, 3469–3478.
• Raleigh, E.A., Lech, K. and Brent, R. (1989). In F.M. Ausebel et al. (Eds.), Current Protocols in Molecular Biology, (p. 1.4). New York: Publishing Associates and Wiley Interscience.
• http://en.wikipedia.org/wiki/Escherichia_coli