Colony morphology, ultrastructure and morphogenesis in Mycoplasma hominis, Acholeplasma laidlawii and Ureaplasma urealyticum.

Colonies of Mycoplasma hominis, Acholeplasma laidlawii (three strains) and Ureaplasma urealyticum were examined by light and electron microscopy and their characteristic morphology, ultrastructure and morphogenesis are described. Mycoplasma hominis and A. laidlawii, PG8 and oral strains, developed typical 'fried-egg' colonies which were remarkably heterogeneous in size. The colonies of A. laidlawii strain NCTC 10116 were more homogeneous and grew mainly on the surface of the agar showing a fine granular appearance. Ureaplasma urealyticum produced smaller, granular colonies which grew deeply embedded in the agar and generally without much surface growth. The cellular ultrastructure in these colonies was also examined. The results indicate that several aspects of colony morphogenesis and ultrastructure varied for each of the three species examined.