TABLE 2.
Reduction in population of E. coli O157:H7 (strain EDL 933) as affected by type and concentration of alkaline cleaner, NaOH, and KOH
| Growth phase | Initial population (log10 CFU/ml) | Treatment temp (°C) | Treatmentb | Reduction in population (log10 CFU/ml)a
|
|||||
|---|---|---|---|---|---|---|---|---|---|
| 2 min
|
10 min
|
30 min
|
|||||||
| 100% concn | 25% concn | 100% concn | 25% concn | 100% concn | 25% concn | ||||
| Logarithmic | 7.49 | 4 | Control | a 0.06 d | 0.06 c | a 0.06 e | 0.06 d | +0.05 e | +0.05 c |
| Cleaner 1 | a 1.97 cd | b 0.04 c | a 6.09 ab | b 0.35 d | a 5.77 bc | b 0.39 c | |||
| Cleaner 2 | b 3.64 bc | a 3.83 a | a 6.93 a | b 5.99 a | a 7.08 ab | b 5.65 a | |||
| Cleaner 3 | a 1.10 d | b+0.28 c | a 3.66 bcd | a 0.28 d | a 3.82 cd | a 0.47 c | |||
| Cleaner 4 | a 4.46 ab | b 0.13 c | a 6.44 a | b 2.02 c | a 6.44 ab | b 2.46 b | |||
| Cleaner 5 | a 0.11 d | a 0.04 c | a 1.34 de | a 0.23 d | a 1.35 e | a 0.34 c | |||
| Cleaner 6 | a 5.57 ab | b 0.40 c | a 5.52 ab | b 2.89 bc | a 7.49 a | b 3.84 ab | |||
| Cleaner 7 | a 6.59 a | b 2.40 b | a 6.36 a | b 4.13 b | a 7.01 ab | b 3.65 b | |||
| NaOH | 3.68 bc | 4.74 abc | 6.44 ab | ||||||
| KOH | 3.75 bc | 2.99 cd | 3.78 d | ||||||
| 7.29 | 23 | Control | a+0.04 e | +0.04 b | a+0.52 e | +0.52 c | +0.63 e | +0.63 c | |
| Cleaner 1 | a 5.11 abc | b 0.89 ab | a 4.72 b | b+0.50 c | a 5.05 abc | b+0.12 c | |||
| Cleaner 2 | a 6.92 a | b 2.03 a | a 7.29 a | b 5.41 a | a 6.98 a | b 6.40 a | |||
| Cleaner 3 | a 1.22 de | a+0.44 b | a 2.86 cd | b+0.37 c | a 4.86 abc | a+0.33 c | |||
| Cleaner 4 | a 6.43 a | b+0.08 b | a 7.29 a | b 1.46 bc | a 6.98 a | b 3.46 b | |||
| Cleaner 5 | a 0.32 e | a+0.34 b | a 1.20 de | a+0.16 c | a 2.28 cd | a+0.40 c | |||
| Cleaner 6 | a 5.22 abc | b 0.98 ab | a 6.67 a | b 3.81 ab | a 6.98 a | b 4.49 ab | |||
| Cleaner 7 | a 5.95 b | b 2.40 a | a 6.91 a | b 3.26 ab | a 5.98 ab | b 4.11 ab | |||
| NaOH | 3.50 bcd | 3.88 bc | 2.41 cd | ||||||
| KOH | 2.72 cde | 3.28 bc | 4.26 bc | ||||||
| Stationary | 8.59 | 4 | Control | a+0.02 f | +0.02 a | 0.05 c | 0.05 c | 0.11 c | a 0.11 bc |
| Cleaner 1 | a 0.30 f | a+0.08 a | a 0.82 c | a 0.07 b | a 1.58 c | a+0.22 c | |||
| Cleaner 2 | a 5.69 a | b+0.16 a | a 6.57 a | b 1.37 ab | a 8.04 a | b 1.85 ab | |||
| Cleaner 3 | a 0.64 ef | a+0.02 a | a 0.49 c | a 0.18 ab | a 1.57 c | a 0.17 bc | |||
| Cleaner 4 | a 3.25 bcd | b 0.27 a | b 0.13 c | a 1.47 a | a 8.59 a | b 1.71 abc | |||
| Cleaner 5 | a 0.05 f | a+0.10 a | a 0.21 c | a 0.13 ab | a 0.57 c | a 0.93 abc | |||
| Cleaner 6 | a 3.66 bc | b 0.11 a | a 4.34 b | b 0.05 b | a 7.68 a | b 0.41 bc | |||
| Cleaner 7 | a 3.99 b | b 0.02 a | a 3.87 b | b 0.42 ab | a 4.99 b | b 2.92 a | |||
| NaOH | 2.38 cd | 2.98 c | 4.16 b | ||||||
| KOH | 2.03 de | 3.96 b | 3.92 b | ||||||
| 8.59 | 23 | Control | a+0.03 d | +0.03 b | +0.01 e | 0.01 b | 0.10 c | 0.10 b | |
| Cleaner 1 | a 0.87 cd | a+0.20 b | a 3.90 bcd | b 0.34 b | a 6.67 a | b+0.36 b | |||
| Cleaner 2 | a 4.37 a | b 1.91 a | a 6.81 ab | b 2.44 a | a 8.59 a | b 3.87 a | |||
| Cleaner 3 | a 0.35 d | a 0.35 b | a 2.39 de | a+0.17 b | a 3.29 b | a 0.14 b | |||
| Cleaner 4 | a 4.03 a | b 0.38 b | a 6.45 abc | b 1.11 ab | a 8.59 a | b 3.95 a | |||
| Cleaner 5 | a 0.35 d | b 0.22 b | a 3.33 cd | a+0.03 b | a 0.18 c | b 0.24 b | |||
| Cleaner 6 | a 4.12 a | b 0.15 b | a 4.96 abcd | b 0.99 b | a 7.86 a | b 3.71 a | |||
| Cleaner 7 | a 2.22 bc | b 1.16 ab | a 7.16 a | b 2.50 a | a 7.22 a | b 5.27 a | |||
| NaOH | 3.51 ab | 3.60 cd | 3.60 b | ||||||
| KOH | 3.54 ab | 2.62 de | 4.12 b | ||||||
Reduction or increase in population based on the initial population (0 min) in 0.05% peptone solution (control). cells were treated for 2, 10, and 30 min in 0.05% peptone (control), 100 and 25% concentrations of alkaline cleaners, 0.025 M NaOH or 0.025 M KOH. Within growth phase, treatment temperature, treatment time, and treatment concentration, mean values that are not followed by the same letter indicate significant differences caused by treatments (P ≤ 0.05). Within growth phase, treatment temperature, treatment, and treatment time, mean values that are not preceded by the same letter indicate significant differences (P ≤ 0.05) caused by treatment concentration.
See Table 1 for description of cleaners.