Comparative properties of spiroplasmas and emerging taxonomic concepts: a proposal.

The major serogroups and distinct subgroups of spiroplasmas seem to represent distinct species. The scheme of classification into these groups was initially based on serologic properties and later supported by the results of studies of DNA-DNA homology and polyacrylamide gel electrophoretic analyses of cellular proteins. Because separate subgroups within the same major serogroup cross-react in growth inhibition tests and other serologic tests, a taxonomic scheme is proposed which implies that certain major criteria for species differentiation within the genus Mycoplasma cannot be appropriately applied to the genus Spiroplasma without modification. Nevertheless, the grouping scheme and proposed speciation satisfy requirements for a species concept that is utilitarian and operational and consistent with recommendations by the International Committee on Systematic Bacteriology, Subcommittee on the Taxonomy of Mollicutes.