Submitted to: Journal of Food Science
Publication Type: Other
Publication Acceptance Date: 11/26/2007
Publication Date: 2/1/2008
Citation: Sommers, C.H., Rajkowski, K.T. 2008. Letter to the Editor. Radiation Sensitivity of Escherichia Coli JM109 and DH5 Alpha. Journal of Food Science. 73(1):vii. Interpretive Summary:
Technical Abstract: Food irradiation is a safe and effective method for inactivation of pathogenic bacteria including Escherichia coli O157:H7 in meat, leafy greens, and complex ready-to-eat foods. When new irradiation technologies are evaluated in pilot plant scale operations or performed under non-biosafety laboratory conditions, non-pathogenic surrogate microorganisms are typically used. In this study the radiation sensitivities of Escherichia coli JM109 and DH5 alpha, which are typically used for cloning and maintenance of plasmid DNA, were compared those of E. coli O157:H7 C9490 and 35150 to determine if they were suitable for use as non-pathogenic surrogates for E. coli O157:H7. When the four E. coli strains were suspended in Butterfields Phosphate Buffer and irradiated (4C) to a dose of 0.45 kGy, DH5 alpha (D-10=51.2 Gy) and JM109 (D-10=61.2 Gy) were 3.74 to 5.02 times more radiation sensitive than C9490 (D-10=229 Gy) and 35150(D-10= 257 Gy). These results indicate that E. coli DH5 alpha and JM109, which carry mutations in genes required for DNA repair and replication, are not suitable as non-pathogenic surrogates for E. coli O157:H7.