Carbon monoxide production from heme compounds by bacteria

Carbon monoxide formation from heme compounds by bacteria was investigated to study microbial hemoprotein catabolism with reference to heme degradation by mammalian tissues. Hemolytic and nonhemolytic bacteria were incubated aerobically and anaerobically with the following substrates: erythrocytes, hemoglobin, myoglobin, cytochrome c, hematin, iron hematoporphyrin, copper hematoporphyrin, protoporphyrin, and bilirubin. After 18 hr at 37 C the evolved CO was measured by gas chromatography. None of the bacteria formed CO anaerobically. Under aerobic conditions both alpha-hemolytic Streptococcus mitis and hemolytic Bacillus cereus formed CO from all of the heme compounds tested, whereas nonhemolytic Streptococcus mitis did not evolve CO from any of the substrates. The hemolytic bacteria did not produce CO when the iron of heme was either replaced by copper or removed, as in copper hematoporphyrin and in protoporphyrin, respectively.