Benzoate mediates the simultaneous repression of anaerobic 4-methylbenzoate and succinate utilization in Magnetospirillum sp. strain pMbN1

Table 1 Anaerobic growth of Magnetospirillum sp. strain pMbN1 with binary mixtures of aliphatic and aromatic acids

		Binary mixture of adaptation and co-substrate
		Phase 1		Phase 2	Phase 3
Adaptation substrate	Co-substrate	OD_max	μ_max(h^-1)	Duration of diauxic lag phase (h)	OD_max	μ_max(h^-1)
Cells adapted to succinate
Succinate (5 mM)	Benzoate (1 mM)	0.30	0.19	2.1 ± 0.1	0.42	0.28
Succinate (5 mM)	4-Methylbenzoate (1 mM)	0.61	0.24	None	None	None
Succinate (5 mM)	4-Hydroxybenzoate (1 mM)	0.43	0.27	3.3 ± 0.1	0.51	0.50
Succinate (5 mM)	Phenylacetate (1 mM)	0.66	0.25	None	None	None
Succinate (5 mM)	Acetate (8 mM)	0.53	0.23	None	None	None
Cells adapted to 4-methylbenzoate
4-Methylbenzoate (1.5 mM)	Benzoate (1.5 mM)	0.27	0.29	4.0 ± 0.0	0.41	0.29
4-Methylbenzoate (1.5 mM)	Phenylacetate (1.5 mM)	0.30	0.29	5.0 ± 0.0	0.45	0.28
Cells adapted to other aliphatic acids
Acetate (8 mM)	Benzoate (1 mM)	0.38	0.18	None	None	None
Acetate (8 mM)	4-Methylbenzoate (1 mM)	0.25	0.16	3.5 ± 0.0	0.32	0.24
Pyruvate (6 mM)	Benzoate (1 mM)	0.30	0.17	1.3 ± 0.3	0.54	0.37
Pyruvate (6 mM)	4-Methylbenzoate (1 mM)	0.54	0.22	None	None	None
Fumarate (5 mM)	Benzoate (1 mM)	0.30	0.17	2.3 ± 0.0	0.43	0.29
L-Malate (5 mM)	Benzoate (1 mM)	0.31	0.44	2.6 ± 0.1	0.49	0.28
Oxaloacetate (6 mM)	Benzoate (1 mM)	0.31	0.19	1.0 ± 0.0	0.42	0.34
Cells adapted to other aromatic acids
4-Hydroxybenzoate (1 mM)	Succinate (5 mM)	0.43	0.32	4.3 ± 0.0	0.49	0.50

Preferentially utilized substrates are highlighted in boldface. Applied substrate concentrations are indicated in parentheses. Values for maximal optical density (OD_max) and maximum specific growth rates (μ_max) are based on three replicate cultures with standard deviations of below 5%. μ_max was calculated from the slope of the active growth phase (m) according to μ_max = m ± 1/ΔOD. In the case of diauxic growth, phase 1 corresponds to the first active growth phase. In the case of monophasic growth, phase 1 corresponds to the only observed active growth phase. If present, phase 3 corresponds to a second active growth phase, with phase 2 representing the diauxic lag phase between phases 1 and 3 (Figure 1). For further details see Additional file 1: Figures S1-S3.

ISSN: 1471-2180