Fermentation process for producing itaconic acid under nitrogen free conditions

1. A method for the production of itaconic acid, which method comprises fermenting a recombinant cell selected from a bacterial cell or a yeast cell capable of producing itaconic acid in a suitable fermentation medium, thereby to produce itaconic acid, wherein:

(a) the recombinant cell: (i) overexpresses cis-aconitate decarboxylase; and (ii) overexpresses a part of the citric acid cycle and/or has reduced activity of a native metabolic route to acetate and/or lactate, wherein overexpression of a part of the citric acid cycle is overexpression of a citrate synthase and/or overexpression of an aconitase and wherein reduced activity of a native metabolic route to acetate is reduced activity of a phosphate acetyltransferase by deleting, disrupting or inactivating the pta gene in the recombinant cell and/or wherein reduced activity of a native metabolic route to lactate is reduced activity of a lactate dehydrogenase by deleting, disrupting or inactivating the ldhA gene in the recombinant cell; and,

(b) the fermentation is carried out under anaerobic conditions, wherein fermentation carried out under anaerobic conditions means a fermentation process run in the absence of oxygen or in which substantially no oxygen is consumed or a fermentation process run under oxygen limited, or micro-aerobical, conditions; and

(c) wherein glutamate production is repressed by carrying out the fermentation under nitrogen free conditions.

2. The method according to claim 1 , wherein the cis-aconitate decarboxylase is an Aspergillus terreus cis-aconitate decarboxylase.

3. The method according to claim 1 wherein production of itaconic acid is accompanied by either ethanol and formate production or H 2 and CO 2 production.

4. The method according to claim 1 , wherein the bacterial cell is E. coli , or wherein the yeast cell is S. cerevisiae.

5. The method according to claim 1 which comprises recovery of the itaconic acid.

6. A method for the production of itaconic acid, which method comprises fermenting a recombinant bacterial cell capable of producing itaconic acid in a suitable fermentation medium, thereby to produce itaconic acid, wherein:

(a) the recombinant cell: (i) overexpresses Aspergillus terreus cis-aconitate decarboxylase; and (ii) overexpresses a part of the citric acid cycle and has reduced activity of a native metabolic route to acetate and lactate, wherein overexpression of a part of the citric acid cycle is overexpression of the gltA gene coding for citrate synthase and overexpression of the acnA gene coding for aconitase and wherein reduced activity of a native metabolic route to acetate is reduced activity of a phosphate acetyltransferase by deleting, disrupting or inactivating the pta gene in the recombinant cell and wherein reduced activity of a native metabolic route to lactate is reduced activity of a lactate dehydrogenase by deleting, disrupting or inactivating the ldhA gene in the recombinant cell; and,

(b) the fermentation is carried out under anaerobic conditions, wherein fermentation carried out under anaerobic conditions means a fermentation process run in the absence of oxygen or in which substantially no oxygen is consumed or a fermentation process run under oxygen limited, or micro-aerobical, conditions; and,

(c) wherein glutamate production is repressed by carrying out the fermentation under nitrogen free conditions.

7. The method according to claim 6 wherein the recombinant bacterial cell is a recombinant E. coli cell.

8. The method according to claim 6 wherein in step (a) the citrate synthase is C. glutamicum citrate synthase.

9. The method according to claim 6 wherein in step (a) the aconitase is C. glutamicum aconitase.

10. The method according to claim 6 wherein in step (b) the fermentation process is run in the absence of oxygen or in which substantially no oxygen is consumed.