CGSC Strain#: 6573
Strain Designation: E. coli B/r      Source of Strain: E.M. Witkin
Other Designations: AC6573
Sex: F- Chromosomal Markers: lon-11, sulA1, Mal(ts), λ^R
Strain Comments:

• Several persons may have isolated radiation-resistant derivatives of E. coli B and called them simply `` E.coli B/r". This designation should be reserved for the original isolate of Witkin.
• lon-11-- is a mutation of an E. coli B gene caused by an IS186 insertion in the promoter. All derivatives of Witkin's B wildtype carry this lon mutation.
• λ^R-- Lambda resistant, locus unknown.
• ts = Temperature Sensitive

References:

• Witkin, EM 1946. Inherited Differences in Sensitivity to Radiation in Escherichia Coli. Proc. Natl. Acad. Sci. U.S.A. 32(3):59-68.