Differences in the growth requirements of some strains of Ureaplasma urealyticum of human origin.

The growth requirements of Ureaplasma urealyticum strains T-McA, T-Pi, T-27, and T-207 were studied. All strains grew in T-broth containing horse serum. Only strain T-McA grew in broth containing serum fraction A, a finding that confirmed that ureaplasmas are not homogeneous and suggested that they can be divided into two species on the basis of their requirement for horse serum. The growth factors required by T-McA are arginine, cystine, methionine, and unidentified metabolites in serum fraction A and trypticase soy broth. The vitamins in Eagle's minimal essential medium are not essential metabolites for T-McA but enhanced its growth. Therefore, we recommend that these vitamins be incorporated in ureaplasma media and that the effect of supplementing media with arginine, cystine, and methionine for the primary isolation of ureaplasmas be ascertained.

Morphology, ultrastructure, and mode of division of Mycoplasma fermentans, Mycoplasma hominis, Mycoplasma orale, and Mycoplasma salivarium.

The morphology of viable Mycoplasma fermentans, Mycoplasma hominis, Mycoplasma orale types 1 and 2, and Mycoplasma salivarium was studied in broth cultures by interference microscopy and in thin sections by electron microscopy. Only spherical cells were seen by interference microscopy. M. hominis had a capsule-like outer layer. Except for M. orale type 1, mycoplasmas in thin sections were 0.3-1 mum in diameter, with a bounding trilaminar membrane 7.5-10 nm thick. The mycoplasmas contained DNA fibrils and randomly distributed ribosomes. No polyribosomes were seen. Dividing mycoplasmas elongated slightly; the membrane invaginated, forming one bud. Sometimes M. hominis and M. salivarium produced one bud by elongation, and the bud was attached by a tube. This method of division is not considered as characteristic but rather as due to centrifugal force separating unfixed cells during preparation for electron microscopy. Cross-septa were never observed. In thin sections M. orale type 1 was elongated and without buds, an observation which suggested that preparation for electron microscopy distorted the mycoplasmas.

A study of the amino acids and proteins of some human T-mycoplasma membranes.

Purified membranes were prepared from seven human T-mycoplasmas. Their amino acid composition was determined and was similar to that of other biological membranes. Their proteins were examined by isoelectric focusing and 7 to 10 protein bands were detected mostly in the pH 4 to 7 range of the gel. T-mycoplasma T-McA also had one distinctive band at pH 3 while T-mycoplasma T-213 had a prominent basic band at pH 9. The proteins were denatured by storage at -25 degrees. Five to seven Periodic Schiff-positive bands also were observed but were not identified.