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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

Itaconic acid production in g/L of the transformants harboring the complete itaconic acid biosynthesis cluster cadA, mttA and mfsA respectively and the modified pfkA (T1-T8) compared to the transformants containing only cadA, mttA and mfsA genes (C1, C2, C3, C4) followed in time (6, 30, 54, 78 hours after induction).
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Figure 5: Itaconic acid production in g/L of the transformants harboring the complete itaconic acid biosynthesis cluster cadA, mttA and mfsA respectively and the modified pfkA (T1-T8) compared to the transformants containing only cadA, mttA and mfsA genes (C1, C2, C3, C4) followed in time (6, 30, 54, 78 hours after induction).

Mentions: Both the strains harboring the itaconic acid production cluster cadA, mttA and mfsA (C series) as well as the transformants carrying the modified pfkA gene together with the itaconic acid biosynthetic cluster (T series) have very variable citric acid production levels (Figure 4). The largest difference was found in the strains that also express the itaconic acid biosynthetic cluster, in which the citric acid level varies between 0.2 and 5.5 g/L at 78 hours after induction. The strains that also express the modified pfkA in combination with the itaconic acid biosynthetic cluster produce significantly higher amounts of itaconic acid (Figure 5) at sampling time point 30 h and 54 h after induction compared to the strains that only harbor the itaconic acid biosynthetic cluster (T-test, p = 0.04 for 30 h and p = 0.003 for 54 h). At t=78 h after induction there were no significantly increased levels of itaconic acid observed (p = 0.15). The total yield, expressed in C-mol, of itaconic acid and citric acid in the cluster strains (C series) ranged between 22% and 37% while the yield of the cluster plus the modified pfkA transformants (T series) ranged between 23% and 44% at t=78 h. This was statistically not significantly higher (p = 0.14) (Figure 6). However, the total C-mol yield of itaconic acid and citric acid is only significantly higher for the pfkA transformants at t=30 h and t=54 h (p = 0.03 and p = 0.03 respectively, data not shown). In addition, the productivity levels were significantly higher (p = 0.03) for the transformants expressing the itaconic acid biosynthetic cluster and the modified pfkA genes compared to the strains that lack the modified pfkA gene.


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)

Itaconic acid production in g/L of the transformants harboring the complete itaconic acid biosynthesis cluster cadA, mttA and mfsA respectively and the modified pfkA (T1-T8) compared to the transformants containing only cadA, mttA and mfsA genes (C1, C2, C3, C4) followed in time (6, 30, 54, 78 hours after induction).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Itaconic acid production in g/L of the transformants harboring the complete itaconic acid biosynthesis cluster cadA, mttA and mfsA respectively and the modified pfkA (T1-T8) compared to the transformants containing only cadA, mttA and mfsA genes (C1, C2, C3, C4) followed in time (6, 30, 54, 78 hours after induction).
Mentions: Both the strains harboring the itaconic acid production cluster cadA, mttA and mfsA (C series) as well as the transformants carrying the modified pfkA gene together with the itaconic acid biosynthetic cluster (T series) have very variable citric acid production levels (Figure 4). The largest difference was found in the strains that also express the itaconic acid biosynthetic cluster, in which the citric acid level varies between 0.2 and 5.5 g/L at 78 hours after induction. The strains that also express the modified pfkA in combination with the itaconic acid biosynthetic cluster produce significantly higher amounts of itaconic acid (Figure 5) at sampling time point 30 h and 54 h after induction compared to the strains that only harbor the itaconic acid biosynthetic cluster (T-test, p = 0.04 for 30 h and p = 0.003 for 54 h). At t=78 h after induction there were no significantly increased levels of itaconic acid observed (p = 0.15). The total yield, expressed in C-mol, of itaconic acid and citric acid in the cluster strains (C series) ranged between 22% and 37% while the yield of the cluster plus the modified pfkA transformants (T series) ranged between 23% and 44% at t=78 h. This was statistically not significantly higher (p = 0.14) (Figure 6). However, the total C-mol yield of itaconic acid and citric acid is only significantly higher for the pfkA transformants at t=30 h and t=54 h (p = 0.03 and p = 0.03 respectively, data not shown). In addition, the productivity levels were significantly higher (p = 0.03) for the transformants expressing the itaconic acid biosynthetic cluster and the modified pfkA genes compared to the strains that lack the modified pfkA gene.

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