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Page 8 of 17 Wottrich et al. Microbiome Res Rep 2024;3:27 https://dx.doi.org/10.20517/mrr.2023.42

Table 4. Bacterial SIR correlates with phage pseudolysogeny, and susceptibility to infection
Test Outcome Uninfected (control) Infected with sustained SIR Infected with loss of SIR
PCR 735 bp band produced 0 27 0
No 735 bp band produced 1 0 2
Spot test Susceptible to infection 1 0 1
Not susceptible to infection 0 1 0
The SI-resistant phenotype was observed in bacteria that yielded a 735 bp band on PCR, indicating that the bacteria with this phenotype contain a
phage undergoing pseudolysogeny. The bacteria no longer exhibiting this phenotype were not associated with a band produced on PCR, nor were
they resistant to infection when challenged with Aquarius. SIR: superinfection resistance.

Figure 2. Phamerator Comparative Genomics Maps. Comparative genomic maps generated using Phamerator.org for the eight C. acnes
phages used in this study. Each genome is arranged along a kilobase ruler with forward transcribed genes marked above the ruler and
reverse transcribed genes marked below the ruler. Each gene product is color coded by related protein “phamilies” or “phams”
determined by BLASTP and ClustalW as described by Cresawn et al. (2011) [34] . Phams with known functions are labeled along the
Aquarius genome map. Nucleotide sequence similarity based on BLASTN is shown by the shaded regions between genomes, and is
colored based on its E value, with violet representing the best matches (lowest E values) and red the worst matches (highest E values).
White areas indicate that there is no nucleotide similarity in those regions. As reported for previously studied C. acnes phages, the
phages used in this study have genomes with a high degree of synteny and nucleotide conservation, as demonstrated by the mostly
violet shading between genomes [3,6,11] .

low-stability group, but complete SIR in the high-stability group, supporting the hypothesis of a
pseudolysogeny-associated phage resistance mechanism.