Specific Growth Rate Determines the Sensitivity of Escherichia coli to Lactic Acid Stress: Implications for Predictive Microbiology

Table 2

Inactivation rates during lactic acid stress (150 mM HLac, pH = 4.6, 𝑎_𝑤=0.92) at 27°C of E. coli 683 harvested at different growth rates. Cells were grown in TSB at 37°C in chemostat or batch culture.

Method	Growth rate at harvest (h^−1)	Number of experiments	Inactivation rate (h^−1)
			Mean (SD)	Minimum	Maximum	CV
Chemostat
Replicate^1 experiments	1.4	3	0.34 (0.05)	0.31	0.40	0.15
	0.2	8	0.11 (0.04)	0.08	0.17	0.36
All experiments	0.17–1.90	21	0.21 (0.12)	0.05	0.40	0.57
Batch
Replicate experiments	1.7	2	0.42 (0.09)	0.36	0.48	0.21
	0.7	2	0.28 (0.07)	0.23	0.33	0.25
	0.2	2	0.07 (0.03)	0.05	0.09	0.43
All experiments	0–1.77	21	0.16 (0.16)	0.01	0.48	1.00

1Experiments at similar growth rates.
SD: standard deviation.
CV: coefficient of variation.