in biology to describe certain organism, which refers to the realms of animals, fungi or plants, developed their own nomenclature.It reflects belonging to the same species depending on the characteristics of morphology and appearance.By the criteria of the animals are applicable to the form, depending on the possibility of giving fertile offspring at fertilization.However, these patterns are only applicable to these organisms, while microbes can not be classified in this manner.
concept of strain in microbiology
Because of the huge number of organisms with morphological properties but different biochemical and immunological features, to name it is impossible to use standard nomenclature.As a result, we put such a thing as a strain.This is a pure culture of bacteria that managed to identify and isolate in a certain place at a certain hour.
Each microbe that belongs to one strain, similar to other such representative biochemical, morphological, genetic and immunological criteria.But within one bacterial species is not observed such an analogy.Because strain - is the name of a more flexible microbial culture.Since the rapid exchange of genetic material (mutation) leads to the appearance of new organisms within a species, but other properties, it is this definition allows more accurately characterize the pathogenicity and virulence factors.
Bacterial strains
existing nomenclature of bacteria allows to classify types of organisms, but does not characterize their new properties.The latter appear as a result of rapid mutation, acquiring new properties, including pathogenic to humans, farm animals and plants, as well as other microbes.An example of the nomenclature of the example of E. coli as follows: Kingdom - bacteria type - proteobacteria, gamma-proteobacteria class, order - Enterobacteriales, the family Enterobacteriaceae.Rod - Escherichia, and the view - Escherichia colli.However, there are many cultures of bacteria species Escherichia colli, showing different properties.They are marked in some strains of bacteria and have the added title.For example, Escherichia colli O157: H7.
very E. coli is present in the intestines of humans and does not cause disease, but strain O157: H7 - extremely pathogenic due to the presence of more virulence factors.She noted enterotoxigenic epidemic diseases in the last 5 years.
Viral strains
strain concept - a flexible title organisms with similar properties that have been isolated and then identified and described in a particular place at a particular time.With its passage virus can acquire new properties due to antigenic drift.This will create a new viral strain, probably more pathogenic than its progenitor.
demonstrate the emergence of new strains can be the example of the influenza virus.It belongs to the family of orthomyxoviruses called depending on the antigens (hemagglutinin and neuraminidase) HxNy.X and Y - are numerical values which reflect the presence of antigens.Example - H5N1, known for the recent epidemic of swine flu with a rapidly progressive hemorrhagic pneumonia.According to the theory of the strain due to the antigenic drift can develop a new and more dangerous strain.
Fungal strains and strains protists
Of all bacteria molds are the least variable, although their biochemistry is also complex.At the expense of a more complex structure than that of bacteria and viruses, and also due to lack of mechanisms for rapid gene transfer of new fungal strains increases slightly.There is also the view that any new recently discovered fungal strains - it existed before the body, which is simply not caught researchers.
similar situation is in the kingdom of protists.Their ability to mutate small because the probability that the new strains appear quickly, extremely small.However, new variants of a single species of organisms still appear.Therefore, apparently, they have also existed previously but has not been detected.
