Primitive atmosphere → small organic molecules → large organic molecules → primitive ocean → primitive life

Simple organic molecules such as amino acids and nucleic acids→Prokaryotes→Eukaryotes

Proposed by Robert. H. Whittaker, living things include the kingdoms Animalia, Plantarum, Fungi, Protists, and Prokaryotes

reason

In the study of biological evolution and systematic classification, a tree-like branch diagram is often used to summarize the genetic relationships between various (types of) organisms. This tree-like branch diagram is called a phylogenetic tree. Phylogenetic trees constructed by comparing the numerical differences between biological macromolecule sequences are collectively called molecular phylogenetic trees.

unique traits

It is the most basic classification unit. It can be defined as a collection of similar strains, which should be significantly different from strains of other groups in terms of performance characteristics, genetic relationships, etc.

A pure species of a microorganism isolated from nature must completely match the recorded characteristics of a known typical species in order to be identified as the same species. Sometimes, most of the characteristics of the isolated pure species are completely consistent with the typical species, but there is a certain characteristic that is different from the typical species, and this characteristic is stable and will not differentiate it into a new species, the microorganism is called Subspecies or variant of a typical bacterial species.

When the character differences between different strains of the same species and the same subspecies are not enough to distinguish them as new subspecies, they can be divided into different types.

In nature, it is often found that some types of microorganisms are between two other microorganisms in terms of characteristics and cannot be strictly distinguished from each other, so they are called the same "group".

Refers to the pure culture of the same microorganism from different sources.

"Identification of Bacteria and Actinomycetes"

Berger's Manual of Identification Bacteriology

"Bacterial Taxonomy"

Ainsworth system

V.Arx System

Kendrick system

"Fungi Dictionary"

Alexopoulos&Mins System

According to the characteristics of nucleic acid structure

Depends on the host

form

Physiology and biochemistry

serology test

Phage typing

It is currently known that the cell wall components of bacteria, molds and yeasts are significantly different, so the cell wall component analysis can be used to classify microorganisms.

It is generally believed that the chemical structure of each substance has a specific infrared absorption spectrum. If the absorption spectra of two samples are exactly the same, they can be initially It was initially believed that they were the same substance, so people used infrared spectroscopy technology to measure the chemical composition of microbial cells to classify microorganisms.

DNA is the main carrier of genetic information, and genetic information is determined by the sequence of the four bases on the DNA chain. Different organisms, and the more distantly related the species, the greater the difference in the sequence of their base pairs. . Therefore, taxonomists consider using the characteristics of DNA, the genetic material of prokaryotic animals, as one of the basis for classification, mainly including GC content measurement, nucleic acid hybridization technology and sequence analysis, etc.

The numerical classification method is developed based on the classification principles published by the French botanist Adanson and with the help of modern computer technology.