IX. IDENTIFICATION OF MYCOPLASMAS
381
information is available (Subcommittee on the Taxonomy of 1clycoplasmatales 1975 ; Edward, 1974). The one species described within this
genus, T. acidophilum, is distinguished by a temperature optimum for
growth of about 59°C and a pH optimum of about 1-2. Sterol is not
required for growth. The genome size is 1 . 0 ~
l o 9 daltons (Christiansen
et al., 1975). It has been recovered up till now only from burning coal
refuse piles.
Note. The description in Sections 111-V of the biochemical and serological methods in the identification of mycoplasmas is prepared with
special reference to those species that are classified within the genera
Mycoplasma, Ureaplasma and Acholeplasma, which together comprise the
vast majority of the species that are of interest to the laboratory worker
concerned with mycoplasmas of human and animal provenance. I n all
essentials, the procedures used to identify these mycoplasmas will also be
applicable to organisms belonging to the genus Spiroplasma. The growth
conditions and hence the techniques to be used for the isolation and
propagation of Anaeroplasma species, and the methods used for their
characterisation and identification, do, on the other hand, differ rather
profoundly from those suitable for the other mycoplasmas. Since moreover
the authors have as yet no personal experience with these organisms, no
further mention will be made of them in this Chapter. Readers having a
special interest in Anaeroplasma species are referred to the papers by
Robinson and Hungate (1973), Robinson et al. (1975), and Robinson and
Allison (1975). Similar considerations hold true for Tlzermcplawia for
which reference should be made to Darland et al. (1970) and Belly et al.
(1973).
C. Species
1. The species concept
The basic unit of biological relatedness is the species. I n organisms that
reproduce sexually species are defined by the ability of their members to
breed with one another. I n organisms that reproduce asexually the species
concept represents a major probleni that has never attained a fully satisfactory solution. Whereas in traditional microbial taxonomy the grouping
of supposedly related strains in the category of a species is based mainly on
phenotypic characters, the burst of nucleic acid homology studies which
has occurred in recent years does in fact represent a genetic approach to
the classification of micro-organisms. For obvious reasons nucleic acid
hybridisation techniques do not offer themselves as a means of routine
identification and classification. Nevertheless, nucleic acid homology data
may, at least under ideal circumstances, provide a rational and meaningful
381
information is available (Subcommittee on the Taxonomy of 1clycoplasmatales 1975 ; Edward, 1974). The one species described within this
genus, T. acidophilum, is distinguished by a temperature optimum for
growth of about 59°C and a pH optimum of about 1-2. Sterol is not
required for growth. The genome size is 1 . 0 ~
l o 9 daltons (Christiansen
et al., 1975). It has been recovered up till now only from burning coal
refuse piles.
Note. The description in Sections 111-V of the biochemical and serological methods in the identification of mycoplasmas is prepared with
special reference to those species that are classified within the genera
Mycoplasma, Ureaplasma and Acholeplasma, which together comprise the
vast majority of the species that are of interest to the laboratory worker
concerned with mycoplasmas of human and animal provenance. I n all
essentials, the procedures used to identify these mycoplasmas will also be
applicable to organisms belonging to the genus Spiroplasma. The growth
conditions and hence the techniques to be used for the isolation and
propagation of Anaeroplasma species, and the methods used for their
characterisation and identification, do, on the other hand, differ rather
profoundly from those suitable for the other mycoplasmas. Since moreover
the authors have as yet no personal experience with these organisms, no
further mention will be made of them in this Chapter. Readers having a
special interest in Anaeroplasma species are referred to the papers by
Robinson and Hungate (1973), Robinson et al. (1975), and Robinson and
Allison (1975). Similar considerations hold true for Tlzermcplawia for
which reference should be made to Darland et al. (1970) and Belly et al.
(1973).
C. Species
1. The species concept
The basic unit of biological relatedness is the species. I n organisms that
reproduce sexually species are defined by the ability of their members to
breed with one another. I n organisms that reproduce asexually the species
concept represents a major probleni that has never attained a fully satisfactory solution. Whereas in traditional microbial taxonomy the grouping
of supposedly related strains in the category of a species is based mainly on
phenotypic characters, the burst of nucleic acid homology studies which
has occurred in recent years does in fact represent a genetic approach to
the classification of micro-organisms. For obvious reasons nucleic acid
hybridisation techniques do not offer themselves as a means of routine
identification and classification. Nevertheless, nucleic acid homology data
may, at least under ideal circumstances, provide a rational and meaningful