Team:TU Darmstadt/Project/Bio/Monomeres/Itaconsaeure

Biotechnological production of itaconic acid in Escherichia coli

Figure 1 Itaconic acid pathway including cis-aconitate decarboxylase

The compilation of our toolbox requires a molecule containing at least two carboxygroups for esterifications with polyalcohols. Furthermore it is important that one compartment of the polymer contains a crosslinking functionality which composes bonds with other strings under specific conditions. A molecule that complies with both requirements is the dicarbonacid itaconic acid, which has an ethylene group that preserves the cross-linking functionality by addition reactions under radical activation.

Itaconic acid is already used as a comonomer for the synthesis of polyacrylates and vulcanized rubber as well as a basic module for biologically degradable polymers that are for example used in the packaging industry. The property to act as a comonomer with different other components has the consequence that itaconic acid is discussed as a possible substitute for methacrylic acid which is utilized to date in the petrochemical industry.  (1)

Figure 2 cis-aconitate decarboxylase (coded by cadA)

The conventional exploitation of itaconic acid is achieved by chemical synthesis or takes place in Aspergillus terreus where amounts of 80g/L are provided. (2) An important disadvantage of the recent production is the high cost of approximately US$4/kg. (3)

A possibility to achieve a better production of itaconic acid in a different host than Aspergillus terreus could be performed by the introduction of a single key enzyme of the Aspergillus terreus.

The cis-aconitate decarboxylase (BBa_K1602003)  encoded by cadA from Aspergillus terreus catalyzes the reaction of cis-aconitate to itaconic acid under loss of carbon dioxide. Cis-aconitate is an intermediate of the TCA-cycle that occurs in most organisms. For that reason there are a lot of different possible hosts. We decided to use Escherichia coli which contains the whole TCA-cycle and is also well characterized as a model organism.

  1. Huang X, Lu X, Li Y, Li X, Li JJ. Improving itaconic acid production through genetic engineering of an industrial Aspergillus terreus strain. Microb Cell Fact. 2014;13:119.
  2. Huang X, Chen M, Lu X, Li Y, Li X, Li JJ. Direct production of itaconic acid from liquefied corn starch by genetically engineered Aspergillus terreus. Microb Cell Fact. 2014;13:108.
  3. Willke T, Vorlop KD. Biotechnological production of itaconic acid.
    Appl Microbiol Biotechnol. 2001;56(3-4):289-95.