FIGURE 3.

Agarose gel of PCRs from ϕSa4ms selective-depletion experiment. One percent agarose gel stained with SYBR Safe DNA Gel Stain containing end-point PCRs from MSSA476 samples. MSSA476 exDNA was digested with Plasmid-safe exonuclease, PshAI/PspXI restriction endonucleases, both Plasmid-safe and restriction endonuclease, or left untreated with treatment indicated by “+” and “–”. Gapdh, ϕSa3ms attP, ϕSa4ms attP, and pSAS1 target were amplified from treated and untreated samples. ϕSa4ms attP target is selectively depleted from combination exonuclease and endonuclease treatment but not solely exonuclease treatment, indicating its existence as a circular element in exDNA samples. Higher levels of ϕSa4ms target compared to ϕSa3ms target correlate with phage enrichment in sequencing. Negative controls for each primer set are shown. The 500 bp ladder band is indicated.