[Characteristics of nucleoside and pyrimidine base metabolism in Corynebacterium glutamicum]

Corynebacterium glutamicum ATCC 13032 can utilize uridine as a sole source of carbon for its growth. Uridine degradation seems to be catalysed by hydrolase since it does not depend on the presence of phosphorus when the enzyme activity is assayed in vitro. Other nucleosides (adenosine, inosine, guanosine, cytidine, thymidine, deoxyuridine, deoxyadenosine, deoxyguanosine) cannot serve as a source of carbon for the growth of the bacterium. The label of thymidine-3H (methyl) is not incorporated into the acid-insoluble fraction of nucleic acids whereas the label of thymine-14C is incorporated. The cells are not susceptible to the presence of fluorodeoxyuridine in the medium but are inhibited by low concentrations (0.01 mcg/ml) of fluorouracil, the inhibition being eliminated with equimolar concentrations of uracil. Therefore, Corynebacterium glutamicum cannot assimilate thymidine or its analogue, fluorodeoxyuridine, in contrast to thymine which can be used as a sole source of nitrogen in the medium.