Patent ID: 7172887

Claim:
A method for producing citric acid, comprising (a) culturing a mutant of a parent cell, wherein the mutant produces less oxaloacetate hydrolase than the parent cell, wherein the oxaloacetate hydrolase (i) has an amino acid sequence that has at least 90% identity with amino acids 1-341 of SEQ ID NO:2; (ii) is encoded by a nucleic acid sequence having at least 90% homology with the cDNA sequence of SEQ ID NO: 1; and/or (iii) is encoded by a nucleic acid sequence which hybridizes under high stringency conditions with the nucleic acid sequence of SEQ ID NO: 1, the cDNA sequence of SEQ ID NO: 1, the complete complementary strand of SEQ ID NO: 1, and/or the complete complementary strand of the cDNA sequence of SEQ ID NO: 1, wherein the high stringency conditions are defined as prehybridization and hybridization at 42Â° C. in 5Ã—SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 50% formamide, followed by washing three times for 15 minutes using 2Ã—SSC, 0.2% SDS at 65Â° C.; and (b) recovering the citric acid.