Bacillus cereus dissociates hemoglobin and uses released heme as an iron source

B. cereus can use hemoglobin, heme, and heme-albumin complex as iron sources, but does not use other iron binding proteins such as transferrin and lactoferrin. B. cereus digests heme-protein complexes and elicits heme release from the proteins, but does not digest transferrin and lactoferrin. Dissociation of heme-proteins corresponded to the use of iron sources by B. cereus. This activity was completely inhibited by EDTA and phosphoramidon, and metalloendopeptidase inhibitors, therefore it appeared that the metalloprotease(s) are related to digestion and use of heme-protein complexes by B. cereus. B. cereus could bind released heme to its cells. These findings suggest that B. cereus can dissociate heme from heme-protein complex, and capture the released heme to use as an iron source.