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Deletion of glucose oxidase changes the pattern of organic acid production in Aspergillus carbonarius.

Yang L, Lübeck M, Lübeck PS - AMB Express (2014)

Bottom Line: Aspergillus carbonarius has potential as a cell factory for the production of different organic acids.The effect of genetic engineering was examined by testing glucose oxidase deficient (Δgox) mutants for the production of different organic acids in a defined production medium.The results obtained showed that the gluconic acid accumulation was completely inhibited and increased amounts of citric acid, oxalic acid and malic acid were observed in the Δgox mutants.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section for Sustainable Biotechnology, Aalborg University Copenhagen, A. C. Meyers Vænge 15, Copenhagen, DK-2450, SV, Denmark.

ABSTRACT
Aspergillus carbonarius has potential as a cell factory for the production of different organic acids. At pH 5.5, A.carbonarius accumulates high amounts of gluconic acid when it grows on glucose based medium whereas at low pH, it produces citric acid. The conversion of glucose to gluconic acid is carried out by secretion of the enzyme, glucose oxidase. In this work, the gene encoding glucose oxidase was identified and deleted from A. carbonarius with the aim of changing the carbon flux towards other organic acids. The effect of genetic engineering was examined by testing glucose oxidase deficient (Δgox) mutants for the production of different organic acids in a defined production medium. The results obtained showed that the gluconic acid accumulation was completely inhibited and increased amounts of citric acid, oxalic acid and malic acid were observed in the Δgox mutants.

No MeSH data available.


The yield of gluconic acid production based on the biomass growth. The yield was calculated based on the results from the samples taken on day 7.
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Figure 3: The yield of gluconic acid production based on the biomass growth. The yield was calculated based on the results from the samples taken on day 7.

Mentions: The gox gene deleted from A. carbonarius is supposed to play a key role in the formation of gluconic acid. In order to evaluate the effect of this genetic modification on gluconic acid production, growth experiments were carried out with the Δgox mutants for 7 days at pH 5.5 by employing the A. carbonarius 5010 and KB1039 (ΔkusA) as control. As shown in Figure 2, the KB1039 (ΔkusA) and wild type strain (5010) produced high amount of gluconic acid (72 g/L and 53 g/L respectively) in the production medium after 7 days, and both of the Δgox transformants only produced 0.1 g/L gluconic acid by the end of the growth experiment. However, in order to confirm that the low gluconic acid production was not caused by different growth rates of the Δgox mutants, the biomass of the Δgox mutants was determined after the growth experiment. As shown in Figure 3, the Δgox mutants produced similar amount of biomass as the parent strain, which indicated that they grew equally well under the same conditions. The result confirmed that deletion of the gox gene can effectively inhibit the formation of gluconic acid by A. carbonarius.


Deletion of glucose oxidase changes the pattern of organic acid production in Aspergillus carbonarius.

Yang L, Lübeck M, Lübeck PS - AMB Express (2014)

The yield of gluconic acid production based on the biomass growth. The yield was calculated based on the results from the samples taken on day 7.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230901&req=5

Figure 3: The yield of gluconic acid production based on the biomass growth. The yield was calculated based on the results from the samples taken on day 7.
Mentions: The gox gene deleted from A. carbonarius is supposed to play a key role in the formation of gluconic acid. In order to evaluate the effect of this genetic modification on gluconic acid production, growth experiments were carried out with the Δgox mutants for 7 days at pH 5.5 by employing the A. carbonarius 5010 and KB1039 (ΔkusA) as control. As shown in Figure 2, the KB1039 (ΔkusA) and wild type strain (5010) produced high amount of gluconic acid (72 g/L and 53 g/L respectively) in the production medium after 7 days, and both of the Δgox transformants only produced 0.1 g/L gluconic acid by the end of the growth experiment. However, in order to confirm that the low gluconic acid production was not caused by different growth rates of the Δgox mutants, the biomass of the Δgox mutants was determined after the growth experiment. As shown in Figure 3, the Δgox mutants produced similar amount of biomass as the parent strain, which indicated that they grew equally well under the same conditions. The result confirmed that deletion of the gox gene can effectively inhibit the formation of gluconic acid by A. carbonarius.

Bottom Line: Aspergillus carbonarius has potential as a cell factory for the production of different organic acids.The effect of genetic engineering was examined by testing glucose oxidase deficient (Δgox) mutants for the production of different organic acids in a defined production medium.The results obtained showed that the gluconic acid accumulation was completely inhibited and increased amounts of citric acid, oxalic acid and malic acid were observed in the Δgox mutants.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section for Sustainable Biotechnology, Aalborg University Copenhagen, A. C. Meyers Vænge 15, Copenhagen, DK-2450, SV, Denmark.

ABSTRACT
Aspergillus carbonarius has potential as a cell factory for the production of different organic acids. At pH 5.5, A.carbonarius accumulates high amounts of gluconic acid when it grows on glucose based medium whereas at low pH, it produces citric acid. The conversion of glucose to gluconic acid is carried out by secretion of the enzyme, glucose oxidase. In this work, the gene encoding glucose oxidase was identified and deleted from A. carbonarius with the aim of changing the carbon flux towards other organic acids. The effect of genetic engineering was examined by testing glucose oxidase deficient (Δgox) mutants for the production of different organic acids in a defined production medium. The results obtained showed that the gluconic acid accumulation was completely inhibited and increased amounts of citric acid, oxalic acid and malic acid were observed in the Δgox mutants.

No MeSH data available.