INVESTIGADORES
MORATA Vilma Ines
capítulos de libros
Título:
Classification of the Bacteria: Traditional
Autor/es:
MORATA DE AMBROSINI V.I.; MARTÍN, M.C.; MERÍN, M.G.
Libro:
Encyclopedia of Food Microbiology (2nd Edition)
Editorial:
Academic Press
Referencias:
Lugar: Londres; Año: 2013; p. 169 - 173
Resumen:
Taxonomy is a subdiscipline of biology that deals with classification
of living beings. Classification involves characterizing,
naming, and grouping organisms according to their natural
relationships. Systematics relates taxonomy with phylogenetics,
which studies the relation among the sequences of
organisms, like a phylogenetic tree (see Bacteria: Classification
of the Bacteria ? Phylogenetic Approach).
Bacterial taxonomy has changed profoundly during recent
decades, incorporating novel identification methods and additional
criteria to describenewspecies.This ?polyphasic taxonomic
approach? involves the combination of phenotypic, genotypic,
and phylogenetic techniques that are necessary to identify and
describe bacteria.The phenotypic study includes morphological,
metabolic, physiological, and chemical characteristics of the cell,
whereas genotypic analysis compares the bacterial genome. With
these two techniques, organisms are grouped according to their
similarities. These studies are complemented with phylogenetics,
which studies the parental relation among microorganisms.
Polyphasic taxonomy also considers the importance of the
habitat of each bacterium and its ecology.
Traditional bacterial taxonomy provides useful identification
methods based on phenotypic characteristics. The prominent
role it used to play in the past is now decreasing, however,
due to the easiness to obtain particular DNA sequences. These
advances in molecular techniques are the cause for the decline
in importance of the traditional approach of taxonomy because
its reliability does not meet modern standards. In fact, newly
developed genetic techniques allow for microbial identification
without the need to culture them, as many microorganisms can
be present in their noncultural state (see Identification
Methods: Culture-Independent Techniques).
In any study involvingmicroorganisms, reliable identification
of isolates is absolutely essential. Identification is possible only
when coherent bacterial classification is available. Bacteria are
classified into a hierarchy of ranks (from high to low): domain,
phylum, class, order, family, genus, species, and subspecies.