Table 5.

Influence of bacterial metabolites on conjugation frequency [log₁₀(CF¹)] of an E. coli donor and a Salmonella Typhimurium recipient, calculated per donor, recipient, and total bacterial count corrected for the stress impact factor.

Organic acid (mM)	CF(D)	CF(R)	CF(T)	CF(D) (SIF)	CF(R) (SIF)	CF(T) (SIF)
Acetate
0	−5. ± 0.2 a	−4.5 ± 0.2	−5.1 ± 0.2	−5.0 ± 0.2	−4.5 ± 0.2	−5.1 ± 0.2
37	−5.0 ± 0.4 ab	−4.3 ± 0.5	−5.1 ± 0.4	−5.0 ± 0.4	−4.3 ± 0.5	−5.1 ± 0.4
74	−5.0 ± 0.2 ac	−4.2 ± 0.6	−5.1 ± 0.2	−4.9 ± 0.1	−4.2 ± 0.6	−5.0 ± 0.1
111	−5.5 ± 0.6 b	−4.6 ± 0.8	−5.6 ± 0.6	−5.4 ± 0.6	−4.6 ± 0.8	−5.5 ± 0.6
148	−5.5 ± 0.6 bc	−4.8 ± 0.3	−5.6 ± 0.5	−5.3 ± 0.6	−4.8 ± 0.3	−5.4 ± 0.5
p-value	0.036	0.231	0.069	0.239	0.231	0.168
Propionate
0	−5.0 ± 0.2 a	−4.5 ± 0.3 a	−5.1 ± 0.2 a	−5.0 ± 0.2 a	−4.5 ± 0.3 a	−5.1 ± 0.2 ab
36	−5.1 ± 0.5 a	−4.4 ± 0.4 a	−5.1 ± 0.5 a	−5.1 ± 0.5 a	−4.4 ± 0.4 a	−5.0 ± 0.5 b
73	−5.5 ± 0.6 ab	−4.8 ± 0.5 a	−5.6 ± 0.5 b	−5.4 ± 0.6 a	−4.8 ± 0.5 a	−5.5 ± 0.5 ac
109	−5.6 ± 0.7 ab	−5.2 ± 0.9 ab	−5.7 ± 0.8 ab	−5.6 ± 0.7 ab	−5.2 ± 0.9 ab	−5.7 ± 0.8 ac
145	−6.8 ± 1.4 b	−6.2 ± 1.5 b	−6.9 ± 1.4 b	−6.9 ± 1.4 b	−6.2 ± 1.5 b	−7.1 ± 1.4 c
p-value	0.002	0.006	<0.001	<0.001	0.006	<0.001
d /l-Lactate
0	−5.0 ± 0.2	−4.6 ± 0.2	−5.1 ± 0.2	−5.0 ± 0.2	−4.6 ± 0.2	−5.1 ± 0.2
29	−5.0 ± 0.3	−4.7 ± 0.2	−5.1 ± 0.4	−5.1 ± 0.3	−4.7 ± 0.2	−5.3 ± 0.2
57	−5.2 ± 0.4	−4.7 ± 0.4	−5.4 ± 0.4	−5.2 ± 0.4	−4.7 ± 0.4	−5.3 ± 0.4
86	−5.0 ± 0.3	−4.6 ± 0.4	−5.2 ± 0.4	−5.0 ± 0.3	−4.6 ± 0.4	−5.1 ± 0.4
114	−5.0 ± 0.3	−4.6 ± 0.2	−5.2 ± 0.3	−5.1 ± 0.3	−4.6 ± 0.2	−5.2 ± 0.3
p-value	0.689	0.440	0.474	0.609	0.749	0.338
n-Butyrate
0	−5.0 ± 0.2	−4.5 ± 0.3	−5.1 ± 0.2	−5.0 ± 0.2	−4.5 ± 0.2	−5.1 ± 0.2
38	−5.1 ± 0.4	−4.2 ± 0.7	−5.1 ± 0.4	−5.0 ± 0.4	−4.2 ± 0.4	−4.9 ± 0.4
76	−5.0 ± 0.4	−4.3 ± 0.2	−5.1 ± 0.4	−5.0 ± 0.3	−4.3 ± 0.2	−5.1 ± 0.3
114	−5.1 ± 0.5	−4.5 ± 0.2	−5.2 ± 0.4	−4.9 ± 0.5	−4.5 ± 0.2	−5.1 ± 0.4
152	−4.6 ± 0.5	−4.0 ± 0.4	−4.7 ± 0.5	−4.6 ± 0.5	−4.1 ± 0.3	−4.7 ± 0.5
p-value	0.439	0.116	0.442	0.302	0.102	0.320

¹ Conjugation frequency (CF) calculated as CF/D = transconjugants/donor, CF/R = transconjugants/recipients or CF/T = transconjugants/total bacterial count; SIF = stress impact factor (Supplementary data, Table S3); p-values were calculated comparing CF of different levels of exposure to the stressor using the nonparametric Kruskal–Wallis test and Mann–Whitney test. Significant differences (p ≤ 0.05) between values are indicated by different superscript letters. Raw data are provided in supplementary data, Table S1.