Abstract
The composition and organization of the Bacillus cereus respiratory system were studied. The abolition of NADH-dependent respiration in vegetative and sporulating cell membranes by near-UV light (360 nm) indicated that electrons reduce oxygen only through a quinone-cytochrome pathway. Difference spectroscopy demonstrated the presence of cytochromes b555, c548, aa3, b562, and a2. This composition and studies with respiratory inhibitors suggested that cytochromes are organized in at least two branches, one being highly sensitive to cyanide.