Thymidine incorporation into Rhizobium meliloti

Thymidine is rapidly catabolized to thymine, beta-aminoisobutyric acid, and carbon dioxide by Rhizobium meliloti cells. The incorporation of labelled thymidine into the DNA of R. meliloti cells can be enhanced by the addition of low concentrations (10-20 micrograms/mL) of deoxyadenosine or other nucleosides (adenosine, uridine, guanosine). However, at high concentrations ( greater than 50 micrograms/mL) these compounds inhibit thymidine incorporation. Conditions to obtain highly radioactive DNA of Rhizobium are described.