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Table 1 Estimation of the de novo demand for anabolic precursors during growth of A. gossypii on complex medium and rapeseed oil

From: Metabolic flux analysis in Ashbya gossypii using 13C-labeled yeast extract: industrial riboflavin production under complex nutrient conditions

Anabolic precursor

Total demand (µmol g −1CDW )

 

Uptake (%)a

De novo biosynthesis (%)

Resulting de novo demand (µmol g −1CDW )

G6P

604.8

12.5 ± 0.4

87.5 ± 0.4

529.2 ± 2.7

F6Pb

821.0

0.0

100.0

821.0

R5Pb

329.9

94.8

5.2

17.3

E4P

238.8

98.0 ± 2.9

2.0 ± 3.4

4.8 ± 7.2

G3Pb

240.4

0.0

100.0

240.4

3PG

707.4

94.8 ± 5.1

5.2 ± 5.0

37.1 ± 36.0

PEP

449.6

97.9 ± 2.9

2.1 ± 2.7

9.6 ± 14.3

PYR

1783.1

96.0 ± 1.0

4.0 ± 1.0

71.5 ± 14.9

AcCoA

6572.7

 

n.d.

n.d.

n.d.

OAA

1124.5

88.5 ± 1.9

11.5 ± 1.9

129.8 ± 20.5

AKG

800.4

60.8 ± 1.5

39.2 ± 1.5

313.7 ± 10.7

NADPH

10,659.9

93.3 ± 0.1

6.7 ± 0.2

721.1 ± 62.3

  1. First, the total precursor demand (total demand) was taken from literature [33] and adjusted for growth on vegetable oil based on [24]. The total demand for each anabolic precursor was covered by two routes: (i) uptake of external building blocks from complex ingredients, which biosynthetically originate from the respective precursor (e.g. alanine, valine, etc. from pyruvate) and (ii) de-novo synthesis of the building blocks from vegetable oil. Correlation of the total demand values with experimental summed fractional labeling (SFLcorr) data from combined results of parallel 13C isotope studies with [13C2] glycine, [13C] formate, [13C5] glutamate, and [U13C] yeast extract (Additional file 1: Tables S2, S3) yielded the measured percentage of (i) the anabolic precursor that could be neglected due to the uptake of advanced metabolites (e.g. amino acids, nucleotides) and (ii) the resulting percentage of de novo precursor demand for growth on complex medium and rapeseed oil, which was then converted into the resulting de novo demand. The full length bar indicates the individual contributions visually: the purple fraction depicts the percentage covered from complex ingredients, while the grey fraction depicts the resulting de novo biosynthetic fraction of the precursor. The de novo demand for acetyl CoA was not specified, which is explained in more detail in Additional file 1: Table S5. 3PG, 3-phosphoglycerate; AcCoA, acetyl-CoA; AKG, α-ketoglutarate; E4P, erythrose 4-phosphate; F6P, fructose 6-phosphate; G3P, glyceraldehyde 3-phosphate; G6P, glucose 6-phosphate; OAA, oxaloacetate; PEP, phosphoenolpyruvate; PYR, pyruvate, R5P, ribose 5-phosphate. Contribution of nutrient uptake from the medium and de novo synthesis of precursors for A. gossypii
  2. aPercentage negligible due to uptake of advanced building blocks, i.e. amino acids or nucleotides, from the medium. In the case of NADPH, the negligible fraction stems from the reduced de novo synthesis and thus, reduced NADPH demand of e.g. amino acids that are readily taken up from the medium
  3. bThe demand for the precursor is assumed. Therefore, no standard deviation could be calculated for the according values
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Microbial Cell Factories

ISSN: 1475-2859

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