Required for the stabilization, possibly via formation of a disulfide bond, of the obligatory competence protein ComGC. Not normally required for production of the secreted lantibiotic sublancin 168, although it can partially substitute for BdbB when the latter is absent. It may also be required for the stability of other secreted proteins. Not required for sporulation. Present in detergent-resistant membrane (DRM) fractions that may be equivalent to eukaryotic membrane rafts; these rafts include proteins involved in signaling, molecule trafficking and protein secretion. A late competence gene, expression is enhanced in the presence of ComK. Cells partially restore cytochrome c oxidase activity in a CcdA-deficient mutant, possibly because the bacteria can no longer oxidize the two heme-binding thiol groups in apocytochrome c. Belongs to the DsbB family. BdbC subfamily.