Differential sulfate uptake by two species of bacteria under light or dark incubation conditions

Sulfur-35 was used as an isotope tracer to study the uptake of sulfate by Corynebacterium striatum, Pseudomonas fluorescens, and Serratia marcescens in a medium free from organic sulfur. In two different experiments, P. fluorescens and S. marcescens were found to take up sulfate faster when incubated in the dark than in the light. This differential sulfate uptake was not observed for C. striatum. Some of the implications of these results are discussed.