Failure to detect o-diphenoloxidase in cultivable mycobacteria obtained from feral armadillos

Abstract

We reported earlier that Mycobacterium leprae separated from lepromatous human as well as armadillo tissues contains an unusual form of o-diphenoloxidase which oxidized several diphenols, including D- and L-DOPA (3,4-dihydroxyphenylalanine) to quinones in vitro. It was not known whether any other species of mycobacterial separated from infected armadillo tissue would show o-diphenoloxidase activity. Recently, a few feral armadillos with mycobacterioses caused by cultivable bacilli became available. The data presented in this report demonstrate that cultivable mycobacteria obtained from the tissues of wild-caught armadillos did not contain the enzyme. Two species of nocardia tested converted DOPA to pigment, but this reaction was found to be non-enzymatic, being unaffected by heating. On the other hand, o-diphenoloxidase of the leprosy bacilli was sensitive to higher temperature. Visual evidence on the occurrence of the enzyme in M. leprae is also presented.