Production of 5-methyluridine by immobilized thermostable purine nucleoside phosphorylase and pyrimidine nucleoside phosphorylase from Bacillus stearothermophilus JTS 859

5-Methyluridine was produced continuously from thymine and inosine by immobilized enzymes, which consisted of thermostable purine nucleoside phosphorylase and thermostable pyrimidine nucleoside phosphorylase obtained from Bacillus stearothermophilus JTS 859. The process was carried out in a column reactor at 60° C for 17 d without any bacterial contamination under non-aseptical conditions. Half-lives of the activity of the immobilized enzymes were 47 d and 4.5 d at 60° C and 70° C, respectively, although half-life of the crude enzyme was only 14 h at 70° C.