Table 3.

Analysis of the specificity of the E. coli A0 34/86 (O83: K24: H31) restriction system

Plasmid (R-M system)\Phage λ.specificity	λ.0	λ.A	λ.E	λ.C4/1
BAC (none)	1	1	1	1
pFFP30 (EcoAI)	2 × 10-3	1	3 × 10-2	1 × 10-2
pGC1 (EcoEI)	1 × 10-3	4 × 10-2	1	6 × 10-2
C4/1 (EcoA0ORF42P)	2 × 10-4	1 × 10-4	5 × 10-4	1

Individual E. coli DH10B clones harbouring BAC C4/1 with EcoA0ORF42P, plasmid pFFP30(EcoAI) and pGC1(EcoEI) were tested for restriction of λ.vir 0 (phage with no modified sites on its DNA), phage λ.vir specificity of EcoAI, EcoEI and C4/1 were produced on DH10B [pCFF30], DH10B [pGC1] and DH10B [BAC C4/1], respectively. The numbers represent the efficiency of plating (e.o.p.) of lambda phage