A Study on the lack of [methyl-3H] thymidine uptake and incorporation by chemolithotrophic bacteria

Five chemolithotrophic bacteria were tested for their ability to incorporate [methyl-³H] thymidine. None of the bacteria incorporated the label, even after incubation for 24 hours. The inability of these bacteria to incorporate thymidine appears to be due to an absence of transport mechanisms for exogenous nucleosides. As a result of these findings, it is concluded that activities deduced from labeled thymidine incorporation measurements probably do not include the activity of chemolithotrophic bacteria.