FIG. 4.

Time step PCR of Ppcob and standard curves. (A) PCR performed with DNA templates equivalent to 0.2 (lanes 1), 1 (lanes 2), 5 (lanes 3), 25 (lanes 4), 125 (lanes 5), 625 (lanes 6), 3,125 (lanes 7), and 15,625 (lanes 8) P. piscicida cells and the PPCOB3F-PPCOB3R primer set. A 5-μl aliquot removed from a reaction tube after 25, 30, or 35 cycles was loaded into each lane. (B) Plot of DNA band intensity (optical density [O.D.]) versus log cell number used in PCR. The dashed lines indicate the range of cell numbers that can be quantified by the time step PCR protocol.