Table 2.

Free amino acids measured in ¹³C-metabolic flux analysis studies using E. coli.

	This study	Mori et al. (2011) [17]	Toya et al. (2010) [19]	Iwatani et al. (2007) [14]
Experimental conditions
Analysis	GC-MS	GC-MS	CE-TOFMS	LC-MS/MS
Culture	Chemostat culture	Chemostat culture	Batch culture	Fed-batch culture
Amino acids
Alanine	+	+	+	+
Valine	+	-	+	+
Leucine	+	+	+	-
Isoleucine	-	-	+	-
Lysine	-	-	+	-
Aspartate	+	+	+	+
Asparagine	-	-	-	+
Threonine	+	-	+	+
Methionine	-	-	-	-
Glutamate	+	+	+	+
Glutamine	-	-	-	+
Arginine	-	-	+	-
Proline	-	-	+	-
Glycine	+	-	+	+
Serine	-	+	+	+
Cysteine	-	-	-	-
Histidine	-	-	+	-
Tyrosine	+	-	+	+
Phenylalanine	+	+	+	+
Tryptophan	-	-	-	-

+: detected; -: not detected.