抄録
A hydroxymethylpyrimidine-requiring mutant of E. coli, 70-17, does not respond to mono- or pyrophosphate ester of the pyrimidine in the growth medium of Davis and Mingioli which contains excess amount of inorganic phosphate that represses the synthesis of alkaline phosphatase. A number of mutant strains which respond to mono- or pyrophosphate ester of the pyrimidine have been isolated from the strain, 70-17, following the mutagenesis of N-methyl-N′-nitro-N-nitrosoguanidine, although they require the phosphate esters for growth in much more amounts than the free form of the pyrimidine in the minimal medium at the short time incubation. One of these strains, 70-17-15, has been identified as a hvdroxymethyl-pyrimidine-requiring, alkaline phosphatase constitutive mutant whose synthetic ability for alkaline phosphatase has no longer been repressed by excess amount of inorganic phosphate present in the medium. Experimental evidence have been obtained that mono- or pyrophosphate ester of hydroxymethylpyrimidine is dephosphorylated by this enzyme, and resulting free form of hydroxymethylpyrimidine is utilized for the thiamine biosynthesis in this organism. The strain is useful for the bioautographic identification and quantitative assay, for mono- and pyrophosphates of hydroxymethylpyrimidine from biological materials.
