Biotechnological production of itaconic acid in Escherichia coli
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)
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.
- 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.
- 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.
- Willke T, Vorlop KD. Biotechnological production of itaconic acid.
Appl Microbiol Biotechnol. 2001;56(3-4):289-95.