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Overexpression of a modified 6-phosphofructo-1-kinase results in an increased itaconic acid productivity in Aspergillus niger.

van der Straat L, Tamayo-Ramos JA, Schonewille T, de Graaff LH - AMB Express (2013)

Bottom Line: The combined expression of pfkA with the itaconic acid biosynthetic cluster resulted in significantly increased itaconic acid production at earlier time points.Also the itaconic acid productivity increased significantly.The maximum itaconic acid productivity that was reached under these conditions was 0.15 g/L/h, which is only a factor 17 lower than the 2.5 g/L/h that according to the US Department of Energy should be achieved to have an economically feasible production process.

View Article: PubMed Central - HTML - PubMed

Affiliation: Microbial Systems Biology, Laboratory of Systems and Synthetic Biology, Wageningen University, Dreijenplein 10, 6703, HB, Wageningen, Netherlands. leo.degraaff@wur.nl.

ABSTRACT
A modified 6-phosphofructo-1-kinase was expressed in a citrate producing Aspergillus niger strain in combination with cis-aconitate decarboxylase from Aspergillus terreus to study the effect on the production of itaconic acid. The modified pfkA gene was also expressed in combination with the itaconic acid biosynthetic cluster from A. terreus, which consists of cis-aconitate decarboxylase cadA, a putative mitochondrial transporter mttA and a putative plasmamembrane transporter mfsA. The combined expression of pfkA and cadA resulted in increased citrate levels, but did not show increased itaconic acid levels. The combined expression of pfkA with the itaconic acid biosynthetic cluster resulted in significantly increased itaconic acid production at earlier time points. Also the itaconic acid productivity increased significantly. The maximum itaconic acid productivity that was reached under these conditions was 0.15 g/L/h, which is only a factor 17 lower than the 2.5 g/L/h that according to the US Department of Energy should be achieved to have an economically feasible production process.

No MeSH data available.


Related in: MedlinePlus

Calculated C-mole yield (%) of itaconic acid and citric acid for each transformant harboring the modified pfkA gene in combination with cadA compared to the control strains that only contain the cadA gene at t=78.
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Figure 3: Calculated C-mole yield (%) of itaconic acid and citric acid for each transformant harboring the modified pfkA gene in combination with cadA compared to the control strains that only contain the cadA gene at t=78.

Mentions: Extracellular itaconic acid and citric acid levels were monitored during a time course experiment that included seven A. niger CAD4 transformants (named T1 to T7), carrying both the cadA gene from A. terreus and the modified pfkA gene from A. niger, plus the parent strain as a control. Overexpression of the modified pfkA gene in the A. niger cadA harboring strain led to a strongly increased citric acid production when compared to the parent strain CAD (Figure 1). All transformants produced significantly higher levels of citric acid. The levels of citric acid produced range between the 4.6 and 9.2 g/L while the parent strain produced only 0.1 g/L under these conditions. However, in contrast to the high increase in observed citric acid production, the combination of the modified pfkA gene and the cadA gene from A. terreus did not lead to an increase in itaconic acid levels, as shown in Figure 2 Four of the analyzed transformants produce slightly more itaconic acid as compared to the parental strain, while three of the transformants produced less itaconic acid 78 hours after induction. The parental strain reached extracellular itaconic acid levels of 240 mg/L while the transformants produced between 159 and 348 mg/L. The combined C-mol yield of citric acid and itaconic acid is strongly improved as a result of the introduction of the modified pfkA gene (Figure 3). The best performing transformant reached a yield of 35%.


Overexpression of a modified 6-phosphofructo-1-kinase results in an increased itaconic acid productivity in Aspergillus niger.

van der Straat L, Tamayo-Ramos JA, Schonewille T, de Graaff LH - AMB Express (2013)

Calculated C-mole yield (%) of itaconic acid and citric acid for each transformant harboring the modified pfkA gene in combination with cadA compared to the control strains that only contain the cadA gene at t=78.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016035&req=5

Figure 3: Calculated C-mole yield (%) of itaconic acid and citric acid for each transformant harboring the modified pfkA gene in combination with cadA compared to the control strains that only contain the cadA gene at t=78.
Mentions: Extracellular itaconic acid and citric acid levels were monitored during a time course experiment that included seven A. niger CAD4 transformants (named T1 to T7), carrying both the cadA gene from A. terreus and the modified pfkA gene from A. niger, plus the parent strain as a control. Overexpression of the modified pfkA gene in the A. niger cadA harboring strain led to a strongly increased citric acid production when compared to the parent strain CAD (Figure 1). All transformants produced significantly higher levels of citric acid. The levels of citric acid produced range between the 4.6 and 9.2 g/L while the parent strain produced only 0.1 g/L under these conditions. However, in contrast to the high increase in observed citric acid production, the combination of the modified pfkA gene and the cadA gene from A. terreus did not lead to an increase in itaconic acid levels, as shown in Figure 2 Four of the analyzed transformants produce slightly more itaconic acid as compared to the parental strain, while three of the transformants produced less itaconic acid 78 hours after induction. The parental strain reached extracellular itaconic acid levels of 240 mg/L while the transformants produced between 159 and 348 mg/L. The combined C-mol yield of citric acid and itaconic acid is strongly improved as a result of the introduction of the modified pfkA gene (Figure 3). The best performing transformant reached a yield of 35%.

Bottom Line: The combined expression of pfkA with the itaconic acid biosynthetic cluster resulted in significantly increased itaconic acid production at earlier time points.Also the itaconic acid productivity increased significantly.The maximum itaconic acid productivity that was reached under these conditions was 0.15 g/L/h, which is only a factor 17 lower than the 2.5 g/L/h that according to the US Department of Energy should be achieved to have an economically feasible production process.

View Article: PubMed Central - HTML - PubMed

Affiliation: Microbial Systems Biology, Laboratory of Systems and Synthetic Biology, Wageningen University, Dreijenplein 10, 6703, HB, Wageningen, Netherlands. leo.degraaff@wur.nl.

ABSTRACT
A modified 6-phosphofructo-1-kinase was expressed in a citrate producing Aspergillus niger strain in combination with cis-aconitate decarboxylase from Aspergillus terreus to study the effect on the production of itaconic acid. The modified pfkA gene was also expressed in combination with the itaconic acid biosynthetic cluster from A. terreus, which consists of cis-aconitate decarboxylase cadA, a putative mitochondrial transporter mttA and a putative plasmamembrane transporter mfsA. The combined expression of pfkA and cadA resulted in increased citrate levels, but did not show increased itaconic acid levels. The combined expression of pfkA with the itaconic acid biosynthetic cluster resulted in significantly increased itaconic acid production at earlier time points. Also the itaconic acid productivity increased significantly. The maximum itaconic acid productivity that was reached under these conditions was 0.15 g/L/h, which is only a factor 17 lower than the 2.5 g/L/h that according to the US Department of Energy should be achieved to have an economically feasible production process.

No MeSH data available.


Related in: MedlinePlus