BioMed Research International

Research Article

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

Table 1

Summary of estimated inactivation rates during lactic acid stress (pH 4.6, 150 mM lactic acid, ) at 20 and 27°C for strain E. coli 683 following culture in TSB medium in chemostat or batch. Surviving cells were quantified on TSA plates.


Exp. Number¹	Growth					Inactivation
Exp. Number¹	Medium²	Method	Temp. (°C)	Biomass (OD₆₀₀)	Rate (h⁻¹)	Rate at 27°C (h⁻¹)	SE⁴ of estimated rate	RMSE⁴ of fit	Mean rate at 20°C (h⁻¹)	SE of estimated rate	RMSE of fit

32	TSB 25%	Chemostat	37	1.29	0.17	0.09	0.01	0.121	0.03	0.005	0.053
33	TSB 25%	Chemostat	37	1.26	0.18	0.08	0.01	0.142	0.01	0.003	0.060
27	TSB 25%	Chemostat	15	0.60	0.20	No result	No result	No result	0.34	0.04	0.549
28	TSB 25%	Chemostat	15	0.98	0.20	0.92	0.12	0.525	0.61	0.05	0.230
12	TSB	Chemostat	37	1.56	0.20	0.13	0.01	0.127	0.03	0.01	0.070
16	TSB	Chemostat	37	0.99	0.20	0.17	0.01	0.066	0.06	0.005	0.063
26	TSB 25%	Chemostat	20	1.62	0.22	0.42	0.06	0.832	0.18	0.02	0.348
34	TSB 25%	Chemostat	37	0.52	0.22	0.08	0.003	0.050	ND	ND	ND
21	TSB 25%	Chemostat	15	0.65	0.23	0.43	0.04	0.138	0.34	0.03	0.097
24_1	TSB 25%	Chemostat	37	0.67	0.23	0.12	0.01	0.074	ND	ND	ND
24_2	TSB 25%	Chemostat	37	0.67	0.23	0.16	0.02	0.242	ND	ND	ND
17	TSB 25%	Chemostat	37	0.80	0.24	0.09	0.01	0.118	0.04	0.004	0.050
20	TSB 25%	Chemostat	20	1.19	0.25	0.32	0.03	0.368	0.21	0.004	0.044
13	TSB	Chemostat	37	0.92	0.40	0.20	0.02	0.059	0.02	0.003	0.087
36	TSB 25%	Chemostat	37	1.00	0.43	0.05	0.01	0.099	ND	ND	ND
38	TSB 25%	Chemostat	37	0.57	0.69	0.07	0.02	0.321	ND	ND	ND
39	TSB 25%	Chemostat	37	0.73	0.75	0.17	0.01	0.082	ND	ND	ND
41	TSB 25%	Chemostat	20	0.82	0.65	0.25	0.03	0.259	ND	ND	ND
18	TSB 25%	Chemostat	37	0.88	1.04	0.32	0.03	0.334	0.17	0.01	0.153
22	TSB 25%	Chemostat	37	1.00	1.11	0.34	0.03	0.296	0.16	0.02	0.196
15	TSB	Chemostat	37	0.75	1.26	0.37	0.03	0.373	0.17	0.01	0.141
14	TSB	Chemostat	37	1.75	1.40	0.27	0.01	0.155	0.14	0.01	0.099
31	TSB 25%	Chemostat	37	0.56	1.40	0.31	0.02	0.234	0.16	0.01	0.091
23	TSB 25%	Chemostat	37	0.69	1.41	0.40	0.01	0.046	0.14	0.01	0.164
37	TSB 25%	Chemostat	37	0.65	1.42	0.31	0.03	0.331	ND	ND	ND
11	TSB	Chemostat	37	0.64	1.50	0.31	0.01	0.107	ND	ND	ND
35	TSB 25%	Chemostat	37	0.55	1.90	0.31	0.01	0.130	ND	ND	ND

10_1	TSB	Batch	37	0.21	0.79	0.33	0.02	0.202	ND	ND	ND
10_2	TSB	Batch	37	1.61	0.69	0.23	0.02	0.223	ND	ND	ND
10_3	TSB	Batch	37	2.39	0.09	0.16	0.03	0.362	ND	ND	ND
10_4	TSB	Batch	37	2.8	0³	0.07	0.01	0.085	ND	ND	ND
19_1	TSB 25%	Batch	37	0.08	1.30	0.39	0.08	0.912	ND	ND	ND
19_2	TSB 25%	Batch	37	1.30	0.20	0.05	0.005	0.054	ND	ND	ND
19_3	TSB 25%	Batch	37	1.44	0	0.01	0.01	0.066	ND	ND	ND
19_4	TSB 25%	Batch	37	1.43	0	0.03	0.02	0.065	ND	ND	ND
29_1	TSB 25%	Batch	37	0.09	1.77	0.36	0.04	0.531	ND	ND	ND
29_2	TSB 25%	Batch	37	0.98	0.23	0.09	0.01	0.074	ND	ND	ND
29_3	TSB 25%	Batch	37	1.26	0	0.01	0.002	0.032	ND	ND	ND
29_4	TSB 25%	Batch	37	0.91	0	0.01	0.004	0.052	ND	ND	ND
29_5	TSB 25%	Batch	37	1.60	0	0.18	0.01	0.054	ND	ND	ND
30_1	TSB 25%	Batch	37	0.11	1.66	0.48	0.04	0.486	ND	ND	ND
30_2	TSB 25%	Batch	37	0.96	0.43	0.17	0.01	0.152	ND	ND	ND
30_3	TSB 25%	Batch	37	1.40	0	0.02	0.005	0.114	ND	ND	ND
30_4	TSB 25%	Batch	37	1.37	0	0.03	0.002	0.159	ND	ND	ND
30_5	TSB 25%	Batch	37	1.33	0	0.02	0.002	0.129	ND	ND	ND
40_1	TSB 25%	Batch	37	0.04	0.91	0.32	0.04	0.434	ND	ND	ND
40_2	TSB 25%	Batch	37	0.76	0.60	0.35	0.01	0.067	ND	ND	ND
40_3	TSB 25%	Batch	37	1.51	0.06	0.01	0.003	0.024	ND	ND	ND
40_4	TSB 25%	Batch	37	0.96	0	0.13	0.01	0.059	ND	ND	ND

ND: not determined.
¹Chemostat results are sorted by growth rate and batch results by experiment and sampling time after start of culturing, that is, along the growth curve.
²100% or 25% TSB.
³Zero growth rate indicates stationary phase in batch experiments.
⁴SE: standard error; RMSE: root mean squared error (the square root of the mean of the sum of squared errors).