TABLE 7.

Average lag phase durations, maximum growth rates, and maximum optical density rates of Listeria monocytogenes 08-5578 and its ΔemrE_Lm mutant exposed to sublethal concentrations of the QAC-based sanitizers E-San and BAC for 24 h at 30°C

Parameter and treatment	Valuea
	08-5578 (WT)	ΔemrELm mutant
Lag-phase duration (h)
E-San
0.8 μl/ml	3.31 ± 0.15	8.45 ± 1.34***
1.6 μl/ml	5.17 ± 0.50	21.02 ± 0.79****
BAC
1 μg/ml	2.87 ± 0.39	6.80 ± 1.40**
2 μg/ml	3.16 ± 0.19	18.58 ± 0.68****
TSB	2.68 ± 0.62	2.79 ± 0.56
Maximum growth rate (increase in OD600/h)
E-San
0.8 μl/ml	0.19 ± 0.03	0.15 ± 0.02*
1.6 μl/ml	0.17 ± 0.02	0.06 ± 0.04***
BAC
1 μg/ml	0.19 ± 0.01	0.15 ± 0.01***
2 μg/ml	0.20 ± 0.02	0.12 ± 0.01***
TSB	0.19 ± 0.03	0.21 ± 0.03
Maximum OD600
E-San
0.8 μl/ml	0.69 ± 0.07	0.60 ± 0.06*
1.6 μl/ml	0.65 ± 0.06	0.23 ± 0.18**
BAC
1 μg/ml	0.68 ± 0.07	0.66 ± 0.11
2 μg/ml	0.66 ± 0.07	0.56 ± 0.04**
TSB	0.67 ± 0.06	0.73 ± 0.07

^aValues represent mean values ± SD for five independent assays, with each sample and treatment measured in duplicate. Statistically significant values are indicated by asterisks (*, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001) (P values were obtained using the unpaired two-tailed t test).