TABLE 2.

Relative ratio of identified metabolites during growth of C. glutamicum under P_i limitation and P_i excess

Name	Derivatization(s)	Monoisotopic mass (Da)	RT (min)a	RIb	Areac (Pi limitation/Pi excess)	Area ratio (Pi limit./Pi excess)	P valued
Lactic acid	2TMSe	234.1108	5.48	1,033	7,337 ± 295/384,667 ± 48,336	0.02	0.005
Glycolic acid	2TMS	220.0951	5.67	1,041	15,300 ± 2,307/5,483 ± 361	2.79	0.017
l-Alanine	2TMS	223.1267	5.97	1,053	9,963 ± 1,767/36,233 ± 13,799	0.27	0.100
	3TMS	305.1663	8.76	1,279	5,900 ± 335/96,467 ± 20,766	0.06	0.017
Phosphate	3TMS	314.0959	7.85	1,236	53,233 ± 28,407/170,000 ± 17,578	0.31	0.003
l-Proline	2TMS	259.1424	8.15	1,250	5,400 ± 1,542/63,433 ± 7,250	0.09	0.003
Succinic acid	2TMS	262.1057	8.32	1,258	49,300 ± 4,078/81,567 ± 15,815	0.60	0.048
Fumaric acid	2TMS	260.0900	8.68	1,275	3,907 ± 457/7,900 ± 123	0.49	0.006
Malic acid	2TMS	350.1401	9.96	1,441	3,880 ± 98/17,833 ± 981	0.22	0.001
Glucosef	5TMS, 1MeOxg	569.2876	13.44	1,852	433,667 ± 12,423/3,757 ± 45	115.44	0.0003
Maltoseh	8TMS, 1MeOx	947.459	16.38	2,659	3,553 ± 983/127 ± 27	28.05	0.027
Trehalosei	8TMS	918.4324	18.49	2,661	433,333 ± 26,312/476,000 ± 17,349	0.91	0.158

^aRT, retention time during gas chromatography.

^bRI, retention index calculated using alkane standards (C₁₀ to C₄₀).

^cIntegrated area of chromatographic peak under P_i-limiting conditions versus P_i-excess conditions. Values are means and standard deviations from triplicate experiments.

^dDetermined by Student's t test.

^eTMS, trimethylsilyl.

^fGlucose levels are relatively uncertain due to possible contamination by glucose of the medium during the extraction process; P_i-limited cells retain high glucose concentrations in the medium after 24 h of cultivation.

^gMeOX, methoxyamine.

^hMaltose was detected only by the EI mode due to its higher molecular mass and was extracted with cold methanol.

ⁱTrehalose data were included despite a P value of >0.05, as trehalose can serve as a precursor for maltose by the action of trehalose synthase (TreS).