The cbbL gene is required for thiosulfate-dependent autotrophic growth of Bradyrhizobium japonicum.

Bradyrhizobium japonicum is a facultative chemolithoautotroph capable of using thiosulfate and H2 as an electron donor and CO2 as a carbon source. In B. japonicum USDA110, the mutant of cbbL gene encoding a large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) was unable to grow using thiosulfate and H2 as an electron donor. The cbbL deletion mutant was able to grow and oxidize thiosulfate in the presence of succinate. These results showed that the major route of CO2 fixation for thiosulfate-dependent chemoautotrophic growth is the Calvin-Benson-Bassham cycle involving RuBisCO in B. japonicum.