Patent 7211421 was granted and assigned to AJINOMOTO CO., INC. on May, 2007 by the United States Patent and Trademark Office.
An Escherichia coli mutant strain deficient in dihydrodipicolinate synthase or dihydrodipicolinate reductase is transformed with a chromosomal gene library of Bacillus methanolicus, and a transformant strain which can grow on a minimal medium is selected. Recombinant DNA which codes for dihydrodipicolinate synthase or dihydrodipicolinate reductase (named dapB) is obtained from the transformant.