Agriculture Reference
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10,000
8,000
6,000
4,000
2,000
0
Background
100000
1000000
10000000
CFU/mL
Figure 18.2.
Sensitivity of NAD(P)H method
.
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
0
3.1x10e4
3.1x10e5
3.1x10e6
CFU/mL
Figure 18.3.
Detection levels of bacteria inoculated onto cantaloupe
.
could measure 10
6
CFU/ml of
E. coli
O157:H7. The solid line in the fi gure represented
twice the value of background and was arbitrarily chosen as the limit of detection.
We spiked cantaloupe surfaces with different levels of
E. coli
O157:H7 in circular
areas of 2 cm diameter. After drying for 1 h to promote adhesion, the spiked area was
removed as discs and incubated in nutrient broth for 3.3 h. As illustrated in Figure
18.3, the NAD(P)H method was able to detect the presence of
∼
3
×
1 0
6
CFU of the
