Partial characterization of the cell walls ofMycobacterium leprae

Cell walls were prepared fromMycobacterium leprae (separated and purified from experimentally infected armadillo),M. tuberculosis, M. smegmatis, andMicrococcus lysodeikticus. The purity of the above wall preparations was confirmed after negative staining and shadow-casting and subsequent observation under the electron microscope. As judged from the electron microscopic observations, the bacteria were of different fragility in the following increasing order:M. tuberculosis, M. smegmatis, M. leprae, andMicro. lysodeikticus. The cell walls were hydrolyzed with 6N HCl, and the amino acids were identified by thin-layer chromatography compared with the authentic standards. With the same purification procedures, it was not possible to obtain satisfactorily pure peptidoglycan fromM. leprae. In leprosy bacilli,meso-DAP was found to be present, ín the walls; however, contamination by nonwall amino acids did not allow the confirmation of previous results, a finding that suggests that glycine completely replaced L-alanine inM. leprae cell walls.