Lack Of Genetic Relatedness Between Mycoplasma-Alvi And Mycoplasma-Sualvi

In hybridization experiments performed with deoxyribonucleic acids extracted from the type strains of Mycoplusma alvi and Mycuplusma sualvi, no hybridization was demonstrated. A representative strain (strain 1161-111) of a supposedly new species that exhibited some resemblance to M. alvi especially showed levels of deoxyribonucleic acid-deoxyribonucleic acid relatedness of less than 4 % with both species. Mycoplaswa alvi Gourlay, Wyld and Leach 1977 (3) and Mycoplasma sualvi Gourlay, Wyld and Leach 1978 (4) share a number of prominent characteristics. The cells of both species are predominantly flask or club shaped with more or less well defined polar structures that probably serve as attachment organelles. In M. alvi each organelle contains a rod-shaped central core, which has not been demonstrated in M. sualvi. Although M. alvi and M. sualvi are facultative anaerobes, the growth of both organisms is better under anaerabic conditions. The biochemical properties of these two species, including utilization of glucose and arginine, are likewise identical. M. alvi is a common inhabitant of bovine alimentary and urogenital tracts, whereas M. sualvi occupies a similar ecological niche in pigs. Serologically, the two species are distinct. The guanine-plus-cytosine contents of the deoxyribonucleic acids (DNAs) of M. alvi and M. sualvi are 26.4 and 23.7 mol% (buoyant density method), respec- tively, and thus demonstrate a significant difference between the two species (3, 4).