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.