Time-resolved amino acid uptake of Clostridium difficile 630Δerm and concomitant fermentation product and toxin formation

Table 1 Substrate uptake of amino acids and glucose supplied in CDMM

Substrate	Initial concentration	Relative abundance in stationary phase	t_{halfmaximal comsumption}	Maximal relative uptake rate
	g/L	%	min	h⁻¹
Glucose	2.0	bdl^a	246 ± 3	0.61 ± 0.07
Proline	0.36	bdl	106 ± 4	0.32 ± 0.02
Cysteine	0.5	bdl	124 ± 4	0.43 ± 0.03
Aspartate	0.27	16.3 ± 0.9	141 ± 8	0.34 ± 0.04
Arginine	0.14	35.7 ± 0.9	148 ± 7	0.20 ± 0.02
Alanine	0.16	19.4 ± 2.8	157 ± 11	0.23 ± 0.02
Leucine	0.38	bdl	161 ± 4	0.49 ± 0.08
Glycine	0.05	bdl	163 ± 7	0.31 ± 0.02
Tryptophan	0.1	45.7 ± 1.0	167 ± 15	0.12 ± 0.01
Serine	0.25	bdl	167 ± 2	0.62 ± 0.03
Isoleucine	0.24	bdl	170 ± 5	0.33 ± 0.02
Methionine	0.12	bdl	170 ± 7	0.45 ± 0.03
Tyrosine	0.24	25.7 ± 0.6	171 ± 17	0.19 ± 0.02
Threonine	0.21	bdl	177 ± 18	0.21 ± 0.01
Phenylalanine	0.20	bdl	177 ± 4	0.44 ± 0.01
Valine	0.27	5.4 ± 0.3	224 ± 13	0.24 ± 0.03
Lysine	0.34	101.0 ± 2.1	No significant consumption
Glutamate	0.80	97.6 ± 3.9	No significant consumption

Composition of casamino acids is based on distribution of amino acids in casein and was confirmed by enzymatic assays (for detailed procedure see Additional file 4); total sampling range up to 660 min, for detailed fits, see Additional file 1; ^abdl, below detection limit

ISSN: 1471-2180