Synthesis of 5-Methyluridine by a Thermophile, Bacillus stearothermophilus JTS 859

Many thermophiles, which can grow at 65°C, were examined as to their ability to produce 5-methyluridine from inosine and thymine (5-methyluracil) in the presence of phosphate and cells as enzyme sources. Bacillus stearothermophilus JTS 859 was selected as a strain that synthesized 5-methyluridine efficiently. The reaction is supposed to be carried out by a combination of a thermostable purine nucleoside phosphorylase and a thermostable pyrimidine nucleoside phosphorylase. Their half-lives were 7200 hr and 400 hr at 63°C, and 148 hr and 14 hr at 70°C, respectively.