Figure 3. Profile of phage ΦV10nluc induced bioluminescence from ground beef artificially contaminated with E. coli O157:H7.
Wild type E. coli O157:H7 C7927 was originally inoculated at 4.68 × 108 (
), 4.68 × 107 (
), 4.68 × 106 (
), 4.68 × 105 (
), 4.68 × 104 (
), 4.68 × 103 (
), 4.68 × 102 (
), 4.68 × 101 (
), 4.68 × 100 (
) CFU per assay (in a total of 40 ml), and the threshold (—) was set at double the background value. The concentration of phage added was 9.23 × 103 pfu ml−1 per assay. At 1 hour intervals, individual light readings were recorded for triplicate samples. The cutoff of the bioluminescence reading was at 2.1 × 107 photons per second which is the upper detection limit of the Sirius luminometer used in this study.