Table 2.

RecD makes recB^D1080A sensitive to mitomycin C

rec alleles*	E.O.P. on mitomycin C
None	<0.01, 0.007
recBCD	0.8,  0.8
recBC	0.9,  0.7
recBD1080ACD	<0.01, 0.006
recBD1080AC	0.8,  0.7

Cultures were grown to mid-log phase in LB broth with 40 μg/ml chloramphenicol, diluted, and plated on LB agar plates with or without mitomycin C (0.25 μg/ml). The efficiency of plating (E.O.P.) is the titer on plates with mitomycin C divided by that on plates without mitomycin C. The results of two experiments in which 75–300 colonies were counted for each determination are shown. 

^*Strains are transformants of strain V2570 [Δ(argA-recC)234 hisD∷kan rpsL31] with the indicated rec alleles present on derivatives of plasmid pACYC184.