A process for the preparation of 5'-guanylic acid and expression vectors for use therein.

摘要

5'-guanylic acid may be produced with higher yield by an enzymatic reaction using, as a source of enzyme, fermented product such as fermented liquor and microbial cells obtained by culturing a transformant of Escherichia coli which is capable of producing 5'-guanylic acid from 5'-xanthylic acid, adenosine-5'-triphosphate and at least one substrate selected from ammonia and glutamine and which is produced by transformation of a strain of E. coli carrying a temperature-sensitive cl repressor with a novel recombinant plasmid prepared by recombination of a DNA fragment carrying the PL promoter located upstream of a gene of 5'-guanylic acid synthetase with a vector DNA. It is possible to culture the transformed microorganism in a medium containing 5'-xanthylic acid, adenosine-5'-triphosphate and at least one member selected from ammonia and glutamine.