Antimicrobial Activity of Copper Alone and in Combination with Lactic Acid against Escherichia coli O157:H7 in Laboratory Medium and on the Surface of Lettuce and Tomatoes
Table 2
Populations of E. coli O157:H7 strains grown in BHI broth (Log CFU/mL) containing different concentrations of copper (Cu) and lactic acid (La) after incubation for 8 h at 37°C.
E. coli O157:H7 strains
Treatments
H1730
43895+
43895−
86.24
Average
Log CFU/mL
Control
10.42
10.40
9.37
9.55
Cu 5 ppm
10.28
10.35
9.34
9.45
Cu 10 ppm
10.25
10.12
9.29
9.42
Cu 20 ppm
9.70
9.20
9.08
9.25
Cu 40 ppm
9.51
9.17
8.98
9.10
La 0.1%
9.45
9.68
8.75
8.45
La 0.1% + Cu 5 ppm
9.40
9.55
7.86
7.60
La 0.1% + Cu 10 ppm
9.31
9.25
7.82
7.30
La 0.1% + Cu 20 ppm
9.15
8.93
7.72
6.95
La 0.1% + Cu 40 ppm
9.10
8.34
7.66
6.87
La 0.2%
7.81
7.30
6.15
6.84
La 0.2% + Cu 5 ppm
7.49
6.90
5.95
5.02
La 0.2% + Cu 10 ppm
7.11
6.82
5.90
5.00
La 0.2% + Cu 20 ppm
6.03
6.02
5.55
4.66
La 0.2% + Cu 40 ppm
5.46
5.51
4.56
4.10
Means (± standard deviation) within the same column not followed by same letters are significantly different (). Initial bacterial population was approximately 3.00 log CFU/mL.
