FIG 7.

Contributions to new spacer acquisition. RecD is dispensable for primed spacer acquisition, RecG and CRISPR2 spacer 1 are necessary for efficient primed spacer acquisition, and CRISPR2 spacer 20 is sufficient for primed spacer acquisition when the mismatches are in positions similar to those of CRISPR2 spacer 1 in the biofilm enrichment assay. After the second challenge in the biofilm enrichment assay, the biofilm population of P. aeruginosa (either the WT or the specified mutant) coincubated with either DMS3vir (first six columns) or DMS3vir-PC (last column on the right) was plated for single colonies. At least 200 colonies under each specified condition from at least two replicates were repatched on LB agar. Isolates that were resistant to DMS3vir and twitch negative were scored as type IV pilus (T4P) mutants, while isolates that were resistant to DMS3vir, twitch positive, and demonstrated spacer acquisition, as determined by PCR of the CRISPR arrays, were scored as spacer acquisition positive. The type IV pilus mutant and spacer acquisition-positive isolates from each condition are displayed as a percentage of the total DMS3vir-resistant population under that condition.