Enhancing itaconic acid production by Aspergillus terreus |
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Authors: | Gregor Tev? Mojca Ben?ina Matic Legi?a |
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Institution: | (1) National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia; |
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Abstract: | Aspergillus terreus is successfully used for industrial production of itaconic acid. The acid is formed from cis-aconitate, an intermediate of the tricarboxylic (TCA) cycle, by catalytic action of cis-aconitate decarboxylase. It could be assumed that strong anaplerotic reactions that replenish the pool of the TCA cycle intermediates
would enhance the synthesis and excretion rate of itaconic acid. In the phylogenetic close relative Aspergillus niger, upregulated metabolic flux through glycolysis has been described that acted as a strong anaplerotic reaction. Deregulated
glycolytic flux was caused by posttranslational modification of 6-phosphofructo-1-kinase (PFK1) that resulted in formation
of a highly active, citrate inhibition-resistant shorter form of the enzyme. In order to avoid complex posttranslational modification,
the native A. niger pfkA gene has been modified to encode for an active shorter PFK1 fragment. By the insertion of the modified A. niger pfkA genes into the A. terreus strain, increased specific productivities of itaconic acid and final yields were documented by transformants in respect to
the parental strain. On the other hand, growth rate of all transformants remained suppressed which is due to the low initial
pH value of the medium, one of the prerequisites for the accumulation of itaconic acid by A. terreus mycelium. |
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