Journal of General Microbiology- ( 1972), 72,501-510 Printed in Great Britain Serological Heterogeneity of Mycoplasma pulmonis

Twelve stock and 15 freshly isolated strains of Mycoplasma pulmonis were examined and compared using four serological techniques. Complement fixation tests and inhibition of growth on solid medium showed that the strains were all M. pulmonis, although, with some strains, only one of these techniques gave an unequivocal result. These tests were confirmed to be specific only at a species level. Gel diffusion and metabolic inhibition techniques revealed heterogeneity of the strains at the subspecies level. The relationship between some strains was statisti-cally significant and stable in vitro and some small groups could be defined. These serogroups bore no relationship to groups formed on the basis of protein patterns produced on polyacrylamide gel electrophoresis of strains of Mycoplasma pulmonis