Phage subclusters can be identified by PCR using subcluster-specific TMP primers. PCR products of the predicted size are amplified using cluster-specific primers as indicated in this example (A) which includes phages from subclusters A1 (lanes 2–3), A2 (4–5), A4 (6–7), B1 (8–9), B3 (11–12), D(13–14), E (15–16), G (17–18), and J (19). DNA ladder is in lane 1 and 10. Subcluster specific TMP primers were designed using Geneious software  and specific primer sequences are reported in Table 2. DNA can be obtained for PCR amplification from various sources (B), including DNA extraction kits (lane 2), boiled spot test using 10 ul, 50 ul, 100 ul (4–6), or from a boiled dilution of high titer lysate (7). A negative control is in lane 3.