09-21-2013, 01:27 PM
Researchers who are engaged in studying the evolution of bacteria are more concerned with the taxonomic classification schemes that allow them to compare the genes that are highly conserved between diverse species. A phylogenetic tree is based upon these comparisons and presents the extent of relatedness among various organisms. Among the novel application of this taxonomic classification is the identification and characterization of pathogens that are non cultivable in the laboratory.
The universal phylogenetic tree was initially developed by American microbiologist Carl Richard Woese consisting of three main divisions namely Archaea, Bacteria and Eucarya for all the living organisms. The basis of the classification was the comparison of the 16s rRNA (ribosomal RNA) sequences. The rRNA sequence comparison between various organisms is very useful since these sequences are efficiently conserved and have a gradual, slow and consistent change rate.
Scientists utilize the phylogenetic trees for a variety of purposes including, studying the features of the extinct species and ancestral lineages, testing of the evolutionary hypothesis and to classify the organisms. Utilizing phylogenies as a base for the classification is relatively a new advance in biology. The key advantages of the phylogenetic classification in comparison to the Linnaean system are that, it provides the information about the evolutionary history and it does not rank the organisms artificially into kingdoms, orders and so on.
Molecular subtyping is essential to verify whether the two strains of bacteria are from the same species or different species. PFGE (Pulsed Field Gel Electrophoresis) is the mainly utilized molecular technique in this analysis. Chromosomal DNA is digested with the aid of a restriction enzyme that creates comparatively infrequent cuts in the DNA and as a consequence produces DNA fragments of different sizes in different strains. The DNA fragments obtained from the different strains are then compared by running them on a gel.
The universal phylogenetic tree was initially developed by American microbiologist Carl Richard Woese consisting of three main divisions namely Archaea, Bacteria and Eucarya for all the living organisms. The basis of the classification was the comparison of the 16s rRNA (ribosomal RNA) sequences. The rRNA sequence comparison between various organisms is very useful since these sequences are efficiently conserved and have a gradual, slow and consistent change rate.
Scientists utilize the phylogenetic trees for a variety of purposes including, studying the features of the extinct species and ancestral lineages, testing of the evolutionary hypothesis and to classify the organisms. Utilizing phylogenies as a base for the classification is relatively a new advance in biology. The key advantages of the phylogenetic classification in comparison to the Linnaean system are that, it provides the information about the evolutionary history and it does not rank the organisms artificially into kingdoms, orders and so on.
Molecular subtyping is essential to verify whether the two strains of bacteria are from the same species or different species. PFGE (Pulsed Field Gel Electrophoresis) is the mainly utilized molecular technique in this analysis. Chromosomal DNA is digested with the aid of a restriction enzyme that creates comparatively infrequent cuts in the DNA and as a consequence produces DNA fragments of different sizes in different strains. The DNA fragments obtained from the different strains are then compared by running them on a gel.
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