Prokaryote Characterization and Identification
The aim of characterization (in the present context) is to obtain a complete collection of data describing the properties of a prokaryotic pure culture, i.e., to develop a description. The aim of “identification” is to equate the properties of a pure cult
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Prokaryote Characterization and Identification HANS G. TRÜPER AND KARL-HEINZ SCHLEIFER
The aim of characterization (in the present context) is to obtain a complete collection of data describing the properties of a prokaryotic pure culture, i.e., to develop a description. The aim of “identification” is to equate the properties of a pure culture with those of a well-characterized and accepted species. When identification in this sense cannot be accomplished, the aim of identification must shift to characterization of a new species, i.e., to a new description. It is clear that the amount of data required for the identification of an isolate with an established species is usually lower than the amount of data collected for characterization. And it is also clear that the final aim of characterization, as mentioned above, is never reached because continuing progress in scientific and technological methods allows the study of an ever-increasing number of characters or properties of a species. Although this continuous progress results in a higher reliability in identification, the practical aim of identification is to base it upon the smallest possible number of characteristics. Therefore, identification in many cases (especially with pathogenic organisms) is a compromise between accuracy and speed. The selected characteristics used for identification usually are weighted and are those that have proved to be significant in distinguishing one organism from another.
Prokaryote Systematics Definitions We may define systematics as the scientific study of organisms with the ultimate object of characterizing and arranging them in an orderly manner. Systematics also might be defined as “the study of organismal diversity and interrelationships.” Following Cowan (1968), systematics includes taxonomy (with its subdivisions, see below) and includes aspects of ecology, biochemistry, genetics, pathology, molecular biology, and microscopy. Taxonomy is often used as a synonym for systematics. Stanier et al. (1986) define taxonomy as “the art of biological classification,” while Simpson (1961) defines it as the theoretical study of classification, including its bases, principles, and rules. Cowan (1968) states that taxonomy consists of: This chapter was taken unchanged from the second edition.
1. Classification, which means the orderly arrangement of units into groups. 2. Nomenclature, which means the labeling of units defined by classification. 3. Identification of unknowns with the units defined by classification and labeled by nomenclature (i.e., identification is the practical application of the arts of classification and nomenclature). Classification is often confused with identification, because identification may be understood either transitively (identification of unknowns with units defined by classification) or intransitively (to describe the identity of a species as such and use it as a basis for classification). Thus Stanier et al. (1986) consider the
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