Comparative Cell Wall Analyses of Morphological Forms Within the Genus Actinomyces

Comparative cell wall analyses were made of mycelial and smooth forms ofActinomyces bovis andA. israelii to determine the changes which occur in the cell wall composition concurrent with a change in morphology, and to evaluate cell wall analyses as a criterion for taxonomic identification within the genusActinomyces . Cell walls of the spider forms ofA. boyis had little or no aspartic acid and a high hexosamine concentration; cell walls of the smooth forms had a high aspartic acid content and low concentrations of hexosamine. Both forms had large amounts of glutamic acid, alanine, and lysine, as previously reported. A strain ofActinomyces , previously identified asA. naeslundii on the basis of morphology and aerobic growth characteristics, was found to have the basic cell wall composition ofA. israelii . When transferred from theActinomyces maintenance broth to a thioglycolate broth, the cells of this strain passed from a mycelial form through a transient filamentous morphology to become diphtheroidal with continued incubation. Concomitantly, the concentrations of glutamic acid relative to alanine decreased, and the hexosamine content increased. Variation in morphology within the speciesA. israelii andA. bovis could not be related to any mutual chemical change of their cell walls.