The naming and classification of microbial life is a necessity to fully understand the various forms microbes consist of. The current system of using binomial nomenclature for organisms had originated from the publication of Species Plantarum, a work of Carolus Linnaeus, a Swedish botanist of the eighteenth century. Linnaeus provided a naming and classification system that had grouped organisms based on characteristic similarity. He grouped organisms that could interbreed successfully into categories known as species. He had grouped species into genera, genera were grouped into families, families were grouped into orders, orders were grouped into classes, classes were grouped into phyla, and phyla were grouped into kingdoms. The name of an organism using Linnaeus’ system consisted of a genus name that was always a noun, and a specific epithet.
This form of using two words to classify an organism was known as binomial nomenclature. Other scientists who are responsible for the current taxonomic rules used today are Carl Woese and George Fox. As biochemical tests and morphology had not provided enough information to classify organism fully, Woese and Fox had sequenced the nucleotides of small subunits of ribosomal RNA, or rRNA, to better understand the relationships between different organisms. As rRNA molecules are present in all cells and are a key component protein synthesis, changes in their nucleotide sequences are presumably very rare. In 1976, Fox and Woese had sequenced the rRNA of an odd group of prokaryotes that had produced methane gas as metabolic waste. This characteristic made these organisms unlike other prokaryotic or eukaryotic organisms. This led to the use of the taxon Domain, which contained the Linnaean taxa of kingdoms. The three domains identified by Woese and Fox were Eukarya, bacteria, and Archaea.
Microorganisms are commonly distinguished using techniques such as physical characteristics, serological tests, biochemical tests, nucleic acid analysis, and phage typing. Physical characteristics of microorganisms can be used as an identification method by comparing and observing the morphology, or shape, of the organism. Serological tests are blood tests that can compare antibody production depending on the species. Biochemical tests are used to determine the ability of an organism to ferment carbohydrates.
Bacteria can be also be differentiated by the composition of fatty acids. Biochemical tests can be used only to identify microbes able to be grown under laboratory conditions. Nucleic acid analysis is used to take the sequence of nucleotides in DNA or RNA to classify specific microbes. Techniques such as polymerase chain reaction, or PCR, can be used to analyze and compare nucleotide sequence. Phage typing is used to identify different bacteriophage, which are viruses that use bacteria as their host. Phage are specific to the hosts they infect, using this, different strains of phage can be determined.