# Implementation Studies of Bacteriophage \(\lambda\) O
## Materials and Methods
### Bacterial and Phage Strains  
The genotype, source and laboratory reference number for bacterial strains 594 (Pm\({}^{-}\)), TC600 (Pm\({}^{+}\)), 594 _dna_B-grpD55 is described in Table 10 in reference [25] as are the reference phages (see also [41]). Y836, Y836 \(P\):kan (Bib11t), Y836 RK\({}^{-}\) ilr566a are described in Table 8 in reference [36]. Examples showing the characterization of RK\({}^{-}\) mutants can be found in [11; 48]. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Name** & **\(\lambda\) Map Position** & **Sequence (\(\lx@paragraphsign\) to 3\(\lx@paragraphsign\)) a** \\ \hline L-37904+18 & 37904-37922 & GCTGCCTCTTTGTTG \\ L-MHI29 & 37905-37922 & GCTCCCTCAAGCTCTCTTTGTTAATGG \\ L20 & 39465-39484 & ACTCCGCTAAAGTGACCC \\ L-22 & 38517-38534 & GCTGCCTTGCTGTTCTG \\ L-PG30 & 38530-38547 & ITGGAAACTGGAGAGCACG \\ L-PG1 & 38784-38801 & AAAATGTCCTTGGAGG \\ L-38985p20 & 38985-39005 & CACGACAAGGCGCGCGCGCGCGCGCGC \\ L-MH32 & 39531-39550 & CACAGATCTATAGCAACACAAACCTGACCTG \\ L-18 & 39980-39996 & ITGCCCGAGCCGCCGCCGCCG \\ L-21 & 40360-40377 & CGCGACACAGTAACCAGCAT \\ R-PG2 & 40747-40764 & GGTGTGCGTCTCGT  
**Acknowledgments:** This work was supported by NSERC Canada Discovery grant 138296 to [PERSON]. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. **Author Contributions:** Performed the experiments and helped analyze the data: [PERSON] and [PERSON]. Conceived, designed the experiments, and wrote the paper: [PERSON]. **Conflicts of Interest:** The authors declare no conflicts of interest. **Abbreviations**  
**Unique \(\lambda\) Terminology:Replicative Killing (RK+) competent phenotype:** A property of _E. coli_ cells that possess a \"defective\" \(\lambda\) prophage that is blocked by one of several means for chromosomal excision. The initiation of bi-directional replication from the prophage, which is normally prevented by an action of the prophage CI repressor--until repression is relieved, results in replication forks that move outward from the defective prophage into the _E. coli_ chromosome. Massive cellular killing occurs, likely due to collisions between _E. coli_-initiated and \(\lambda\)-initiated opposing replication forks. **Replicative Killing (RK-) defective phenotype:** Mutants originating in RK+ cells that have lost the RK+ phenotype. There are numerous possibilities for **RK- mutants**, but they all relate to being defective in a phage or host function required for the initiation of \(\lambda\) bi-directional replication. **RK- Hd- mutants** are defective in a host function required for \(\lambda\) replication initiation. **RK+ ilr mutants** are defective in a \(\lambda\) function required for the initiation of \(\lambda\) bi-directional replication, where ilr designates initiation of \(\lambda\) replication defective **RK- FI- mutants** represent RK- mutants where the _imm_ region of the defective prophage cannot be rescued using a phage-prophage marker rescue recombination assay. The hundreds of mutants characterized have resulted from large chromosomal deletions where the deletion endpoints straddle or partially straddle the defective prophage; but they could also represent defects in _pR_, preventing _pR-cro-clI-O-P_ transcription. _imm_**region:** part of the \(\lambda\) genetic map between genes \(N\) and _clI_ that includes the genetic elements _oL/PL-rexA-cI_[Ts857]_-ro/pR-cro. _imm_**434 region:** the region of a \(\lambda\)_imm_434 hybrid phage where the _imm_ region of \(\lambda\) is replaced by DNA from phage 434, but all the remaining portions of the phage genetic map are the same as for \(\lambda\). **FI functional immunity assay:** a marker rescue assay where the _imm_ region of a prophage (in RK+ cells) is rescued by an infecting \(\lambda\)_imm_434 phage, where the recombinant \(\lambda\)_imm_434 prophage released can form plaques on cells lysogenized by a _simm_434 prophage.