Table 2 Excess of M+1 and M+2 isotopologues in amino acids and fatty acids obtained from culture N47 grown with either H13CO3-/13CO2 (10 atom% 13C) or [U-13C10]naphthalene (10 atom% 13C)

From: Chemoorganoautotrophic lifestyle of the anaerobic enrichment culture N47 growing on naphthalene

 

Mass of fragment (M)

[U-13C]naphthalene

13CO2

M+1 (%)

M+2 (%)

M+1 (%)

M+2 (%)

Alanine

260

2.4 (±0.4)

0.4 (±0.2)

7.8 (±0.3)

<0.1 (±0)

Aspartate

418

3.8 (±0.3)

0.5 (±0.2)

11.3 (±0.3)

0.5 (±0)

Glutamate

432

6.4 (±0.3)

2.0 (±0.4)

10.5 (±0.3)

0.4 (±0)

Fatty acid C16:1

74

2.8

1.5

11.0

2.2

Fatty acid C18:1

74

<1.0

0.5

5.7

4.4

  1. Each value depicts the 13C-excess [%] plus standard deviation (σ) in the respective amino acids as the mean of three different cultures analyzed three times each with GC-MS. The excess is the increase of 13C per carbon atom compared to the natural abundance. For the GC-MS measurements of fatty acids, the three separate cultures were combined to increase the amount of substance. Amino acids were measured as TBDMS-derivatives and fatty acids were measured as methyl esters. Hence, values given for the subsequent GC-MS measurements depict the mean from three different samples and standard deviations could not be calculated separately. The fragment [M-57]+ (having lost a tert-butyl moiety from the TBDMS derivatives) was used for the 13C-excess quantification in case of amino acids where M is the mass of the molecule without any fragmentation, the structures of the fragments can be seen in Fig. S9. For fatty acids, typical fragments with a mass of 74 (McLafferty fragments, see Fig. S8) were measured.
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