Improved cysteine-producing strains
AssigneeWacker Chemie AG
InventorsRupert PFALLER, Johanna KOCH
Life of this patent
Estimating the term…
Abstract
Genetically modified microorganism strains for the fermentative production of cysteine provide higher yields of L-cysteine or L-cystine during fermentation. Cysteine production is improved in the genetically modified microorganism strains by attenuating or inactivating phosphoenolpyruvate synthase enzyme activity, alone or in combination with the overexpression of efflux proteins and proteins that reduce feedback inhibition by cysteine and by serine.
Claims19
-12. (canceled)
A microorganism strain suitable for fermentative production of L-cysteine, comprising a genetically modified microorganism strain having inactivated or reduced enzyme activity relative to the activity of the corresponding wild-type enzyme of the enzyme class identified by the number EC 2.7.9.2 in the KEGG database;
- and increased L-cysteine production relative to a microorganism strain having wild-type enzyme activity of the enzyme class identified by the number EC 2.7.9.2 in the KEGG database,
- wherein the gene encoding said enzyme activity is ppsA.
A fermentative process for producing L-cysteine, comprising:
- providing a microorganism strain, selected from the group consisting of Escherichia coli, Pantoea ananatis and Corynebacterium glutamicum and suitable for fermentive production of L-cysteine, wherein the strain comprises inactivated or reduced PpsA enzyme activity relative to the activity of the corresponding wild-type PpsA enzyme, and increased L-cysteine production relative to a microorganism strain having wild-type enzyme activity of the PpsA enzyme;
- culturing the microorganism strain under fermentation conditions to produce L-cysteine;
- and
- collecting the cysteine from the culture.
The process of claim 31, wherein the microorganism strain further comprises at least one mutation in a ppsA gene, selected from the group consisting of the ppsA gene from Escherichia coli, the ppsA gene from Pantoea ananatis, and a gene homologous to these genes, wherein a gene homologous to these genes is a DNA sequence which is at least 80% identical to these genes.
The process of claim 32, wherein the microorganism strain overexpresses a serine O-acetyltransferase protein having a reduced feedback inhibition by cysteine;
- the efflux gene;
- and a serine feedback-resistant variant of 3-phosphoglycerate dehydrogenase.
Dependencies are inferred from the claim text.