Modified microorganism with improved biomass separation behaviour

1. A modified microorganism having, compared to its wild-type, a deletion of the wcaJ-gene or an introduction of at least one mutation into the wcaJ-gene that leads to the expression of a truncated enzyme encoded by the wcaJ-gene in which at least 100 amino acids of the wild-type enzyme encoded by the wcaJ-gene are deleted from the C-terminal end;

wherein the wild-type from which the modified microorganism has been derived belongs to the family of Pasteurellaceae and wherein the wild-type refers to the naturally occurring microorganism that has not been genetically modified,

wherein the wcaJ-gene in the wildtype comprises a nucleic acid

encoding an amino acid sequence which is at least 95% identical to SEQ ID NO: 4 over the total length of the amino acid sequence of SEQ ID NO: 4.

2. Modified microorganism according to claim 1 , wherein the wild-type from which the modified microorganism has been derived has a 16S rDNA of SEQ ID NO: 1 or a sequence, which shows a sequence homology of at least 96% with SEQ ID NO: 1.

3. Modified microorganism according to claim 1 , wherein the wild-type from which the modified microorganism has been derived belongs to the genus Basfia.

4. Modified microorganism according to claim 3 , wherein the wild-type from which the modified microorganism has been derived belongs to the species Basfia succiniciproducens.

5. Modified microorganism according to claim 4 , wherein the wild-type from which the modified microorganism has been derived is Basfia succiniciproducens strain DD1 as deposited under DSM 18541 with the DSMZ, Germany.

6. Modified microorganism according to claim 1 , wherein the microorganism further has, compared to its wild-type,

i) a reduced pyruvate formate lyase activity,

ii) a reduced lactate dehydrogenase activity, or

iii) a reduced pyruvate formate lyase activity and a reduced lactate dehydrogenase activity.

7. Modified microorganism according to claim 6 , wherein the microorganism comprises:

A) a deletion of the ldhA-gene or at least a part thereof, a deletion of a regulatory element of the ldhA-gene or at least a part thereof or an introduction of at least one mutation into the ldhA-gene;

B) a deletion of the pflD-gene or at least a part thereof, a deletion of a regulatory element of the pflD-gene or at least a part thereof or an introduction of at least one mutation into the pflD-gene;

C) a deletion of the pflA-gene or at least a part thereof, a deletion of a regulatory element of the pflA-gene or at least a part thereof or an introduction of at least one mutation into the pflA-gene;

D) a deletion of the ldhA-gene or at least a part thereof, a deletion of a regulatory element of the ldhA-gene or at least a part thereof or an introduction of at least one mutation into the ldhA-gene

and

a deletion of the pflD-gene or at least a part thereof, a deletion of a regulatory element of the pflD-gene or at least a part thereof or an introduction of at least one mutation into the pflD-gene;

or

E) a deletion of the ldhA-gene or at least a part thereof, a deletion of a regulatory element of the ldhA-gene or at least a part thereof or an introduction of at least one mutation into the ldhA-gene

and

a deletion of the pflA-gene or at least a part thereof, a deletion of a regulatory element of the pflA-gene or at least a part thereof an introduction of at least one mutation into the pflA-gene.

8. A method of producing an organic compound comprising:

I) cultivating the modified microorganism of claim 1 in a culture medium comprising at least one assimilable carbon source to allow the modified microorganism to produce the organic compound, thereby obtaining a fermentation broth comprising the organic compound;

II) recovering the organic compound from the fermentation broth obtained in process step I),

wherein the organic compound is a carboxylic, dicarboxylic or tricarboxylic acid.

9. Method according to claim 8 , wherein the organic compound is succinic acid.

10. Method according to claim 8 , wherein the assimilable carbon source is selected from the group consisting of sucrose, maltose, D-glucose, glycerol, mixtures of glycerol and D-glucose, mixtures of glycerol and sucrose, mixtures of glycerol and D-xylose, mixtures of glycerol and mixtures of maltose and D-glucose and fructose.

11. Method according to claim 8 , wherein the process further comprises the process step:

III) conversion of the organic compound contained in the fermentation broth obtained in process step I) or conversion of the recovered organic compound obtained in process step II) into a secondary organic product being different from the organic compound by at least one chemical reaction.

12. Method according to claim 11 , wherein the organic compound is succinic acid and wherein the secondary organic product is selected from the group consisting of succinic acid esters or polymers thereof, tetrahydrofuran (THF), 1,4-butanediol (BDO), gamma-butyrolactone (GBL) and pyrrolidones.