Abstract
Some strains of Mycoplasma mycoides subsp. mycoides, mostly isolated from goats, grow to greater turbidity in broth and form larger colonies on solid medium than does the type strain, PG1. These strains also digest casein, liquefy inspissated serum actively and survive longer at 45 degrees C and are referred to as LC (large colony) strains. Strains more closely resembling PG1 have been called SC (small colony) strains. The SC strains comprise those from contagious bovine pleuropneumonia (CBPP) and some from goats. One LC strain was isolated from a steer; all others have come from goats. Differentiation of M. mycoides subsp. mycoides into 2 types on the basis of the characteristics described may be relevant to their role in CBPP.