Fig. 3 Agarose gel electrophoresis demonstrating detection sensitivity of PCR for nontoxigenic E. coli O157:H7 strain 3704 after 8 h primary
enrichment of Glencorse soil. Lanes: (A and M) HyperLadder (Bioline, UK, Ltd); (B) negative control (no template); (C) positive control pure
culture DNA; (D) negative control, uninoculated soil; (E) 1á36 ´ 101
; (F) 1á36 ´ 102
; (G) 1á36 ´ 103
; (H) 1á36 ´ 104
; (I) 1á36 ´ 105
; (J) 1á36 ´ 106
;
(K) 1á36 ´ 107 and (L) 1á36 ´ 108 cfu g±1 soil