Taxonomy (Greek : taxis = arrangement or order), and nomos = law, or nemein = to distribute or govern) refers to the science or discipline that essentially deals with the logical arrangement of living things into categories. It may also be defined as ‘the laws and principles of classification of living organisms’.
TAXONOMY
Taxonomy (Greek : taxis = arrangement or order), and
nomos = law, or nemein = to distribute or govern)
refers to the science or discipline that essentially deals with the logical
arrangement of living things into categories. It may also be defined as ‘the laws and principles of classification
of living organisms’.
Aristotle—in fact, was the first ever
taxonomist in the fourth century BC who painstakingly and meticulously categorized the so-called ‘living objects’ in the universe into almost 500 well defined
species of plant and animal kingdoms.
Carolus Linnaeus (1735 – 1759) — a renowned
Swedish botanist, virtually named a relatively much larger segment of plants and animals and classified them with
great skill and wisdom into the two predominant kingdoms, namely : Plantae and Animalia. In reality, Carolus was instrumental in devis-ing the
unique ‘Binomial Scheme of
Nomenclature’.
Ernst H Haeckel — in the year 1866 logistically
segregated the ‘microorganisms’ from
the existing plant and animal
kingdoms. It was Ernst who first and foremost introduced the new terminology Protist exclusively reserved for the microorganisms. He subsequently coined another term Protista to specifically and categorically include algae (microscopic), fungi,
and protozoa thereby forming a ‘third
kingdom’.
Comments : (1) There was disapproval with regard to the inclusion of both
bacteria and fungi together in the aforesaid kingdom Protista.
(2) Bearing in mind the recent advances in the
domain of ‘Cell Biology’, profuse ob-jections were raised pertaining
to the two or three kingdom classification schemes as encountered in Protista.
Robert H Whittaker (1969) — duly
put forward a most scientific, plausible, and logical system of classification of the living
organisms which was widely accepted by the modern microbiologists across the
world. However, Robert’s system articulately recognizes the five kingdoms applicable to all living
things, namely: Monera, Protista, Fungi,
Animalia, and Plantae.
Monera — predominantly includes bacteria and cyanobacteria.
Protista — essentially comprises of eukaryotes and protozoa.
Fungi — specifically belongs to the
organisms attached to the kingdom of fungi.
Animalia and Plantae —
particularly include the traditional animals and plants.
It is,
however, pertinent to mention here some of the main terminologies, one may
frequently come across in the proper and elaborated description of the taxonomy of microorganisms, such as: (a) Species
– i.e., the fundamental rank in the
classification system; (b) genus – i.e., clubbing together of two or more species ; (c) family – i.e., the collection of genera; (d) order – i.e., the collection of families with identical characteristic
features ; (e) class – i.e., the arranging together of order ; (f) phylum (or division) – i.e., grouping together of classes;
and (g) kingdom – i.e.,
collection of two or more phyla.
Taxon, also known as the basic
taxonomic group represents the species i.e., a collection of strains with almost similar
characteristic features. In usual practice, the microbial species invariably comprise of a specialized typical
strain termed as the type strain,
along with all other strains which are regarded very much identical to the type strain so as to justify their
logical inclusion in the species. In other words, the type strain is symbolized and designated to be the permanent reference specimen for the
species. However, it may be stressed that it is not necessarily always the
particular strain which happens to be most characterwise typical of all the
strains strategically included in the species,
whereas it is essentially the specific strain to which all the rest of the
strains should be critically compared to ascertain, whether they do have a
close resemblance sufficient enough to belong to the same species. The above glaring statement of facts pertaining to the type strains are extremely vital and
important; and, therefore, specialized and particular attention need to be
given to their genuine and regular mainte-nance as well as preservation. The
following are two world famous
reference collection centres located in USA and UK, namely:
(a) American Type Culture Collection (ATCC),
Rockville, Maryland, USA, and
(b) National
Collection of Type Cultures (NCTC), UK.
Interestingly,
one may critically observe that the various strains strategically present very much within species may differ slightly from one another in three prominent manners, namely:
(a) Biovars: These are variant bacterial
strains and are duly characterized by biochemical
or physiological characteristics.
(b) Morphovars: These are variants within a
species defined by variation in morphological
characteristics.
(c) Serovars: These are variants within a
species defined by variation in serological
reactions.
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