The shxVW genes of Paracoccus pantotrophus were identified to be essential for lithotrophic oxidation of sulfur and hydrogen. shxV predicts a membrane protein which is 42% identical to CcdA of P. pantotrophus essential for cytochrome c biogenesis. shxW predicts a periplasmic thioredoxin. Disruption of shxV by an Ω-kanamycin interposon disabled the resulting mutant GBΩV to grow with thiosulfate or molecular hydrogen and to express ShxW while cytochrome c formation was not affected. Mixotrophic growth with succinate and thiosulfate of strain GBΩV revealed 2% of the thiosulfate-dependent oxygen uptake rate as compared to the wild-type while antigens of proteins essential for sulfur oxidation were present in both strains. Mixotrophic growth of strain GBΩV with succinate and molecular hydrogen revealed neither hydrogenase activity nor antigens. Complementation analysis with plasmid pBHP6 carrying the shxVW genes revealed the wild-type phenotype of strain GBΩV(pBHP6).