Cytochemical evidence for aerobic pathways in Mycobacterium lepraemurium

Three enzymes of aerobic pathways (cytochrome c oxidase, peroxidase and catalase) and one key enzyme of the tricarboxylic acid cycle (succinate dehydrogenase) were investigated for their ultrastructural localization in M. lepraemurium in infected mouse liver and in cultures of M. fortuitum as a control. All four enzymes were localized in M. fortuitum. To M. lepraemurium only cytochrome c oxidase and peroxidatic activity were detected. The localization of the latter enzyme activity was different compared with M. fortuitum. Succinate dehydrogenase was not detected in M. lepraemurium but rather surprisingly was found in the membrane of the phagosomes containing the bacteria. It is concluded that M. lepraemurium can function aerobically and has either a glyoxalate pathway or is an obligate autotroph.