Patent ID: 7776566

Claim:
A method for producing a purine nucleoside by fermentation comprising: culturing an Escherichia coli microorganism in a culture medium to produce and accumulate the purine nucleoside in the medium, and collecting the purine nucleoside, wherein said microorganism has purine nucleoside-producing ability and is modified to block reactions catalyzed by succinyl-adenosine monophosphate synthase, purine nucleoside phosphorylase, adenosine deaminase, 6-phosphogluconate dehydrase, adenine deaminase, and phosphoglucose isomerase, said succinyl-adenosine monophosphate synthase being encoded by a gene obtained by PCR amplification employing the primer pair of SEQ ID NO: 3 and SEQ ID NO: 4 and Escherichia coli chromosomal DNA as the template, said purine nucleoside phosphorylase being encoded by a gene obtained by PCR amplification employing the primer pair of SEQ ID NO: 5 and SEQ ID NO: 6 and Escherichia coli chromosomal DNA as the template, said adenosine deaminase being encoded by a gene obtained by PCR amplification employing the primer pair of SEQ ID NO: 11 and SEQ ID NO: 12 and Escherichia coli chromosomal DNA as the template, said 6-phosphogluconate dehydrase being encoded by a gene obtained by PCR amplification employing the primer pair of SEQ ID NO: 20 and SEQ ID NO: 21 and Escherichia coli chromosomal DNA as the template, said adenine deaminase being encoded by a gene obtained by PCR amplification employing the primer pair of SEQ ID NO: 24 and SEQ ID NO: 25 and Escherichia coli chromosomal DNA as the template, said phosphoglucose isomerase being encoded by a gene obtained by PCR amplification employing the primer pair of SEQ ID NO: 22 and SEQ ID NO: 23 and Escherichia coli chromosomal DNA as the template, wherein said microorganism is further modified to desensitize feedback inhibition of phosphoribosyl pyrophosphate amidotransferase, said phosphoribosyl pyrophosphate amidotransferase being encoded by a gene obtained by PCR amplification employing the primer pair of SEQ ID NO: 1 and SEQ ID NO: 2 and Escherichia coli chromosomal DNA as the template, and wherein said microorganism is further modified to inactivate a purine repressor, said purine repressor being encoded by a gene obtained by PCR amplification employing the primer pair of SEQ ID NO: 7 and SEQ ID NO: 8 and Escherichia coli chromosomal DNA as the template.