Microbial classification
Morphological characteristics"
(1) Individual morphology microscopic examination of cell shape, size, arrangement, Gram staining reaction, motility, flagella position, number, presence or absence of spores, shape and location, capsule, cell contents; actinomycetes and fungi Mycelial structure, shape and structure of spore silk, sporangia or spore ear, shape, size, color and surface characteristics of spores.
Training characteristics
1) Lawn traits (shape, gloss, transparency, color, texture, etc.) on colonies and slopes on solid medium plates;
2) growth of the inoculation culture in a semi-solid medium;
3) The degree of turbidity in the liquid medium, the liquid surface has a sterile membrane, a fungus ring, a flocculent precipitate at the bottom of the tube, the color of the culture solution, and the like.
Physiological and biochemical characteristics
(1) Energy metabolism uses light energy or chemical energy;
(2) Oxygen requirements: obligate aerobic, microaerobic, facultative anaerobic and obligate anaerobic;
(2) The types of carbon sources and nitrogen sources required for nutrition and metabolic properties, whether there are special nutritional needs, and the types of enzymes present.
Ecological habit
Growth temperature, pH, halophilicity, pathogenicity, parasitism, symbiotic relationship, etc.
Serological response
Antisera are prepared from known strains, strains or strains, and then an unknown strain, type or strain is determined based on whether they are serologically specific to the microorganism to be identified.
Phagocytic reaction
The parasites of the cells are specific, and plaques are produced on the plates with sensitive bacteria. The shape and size of the spots can be used as the basis for identification; in liquid culture, the inoculating solution of the phage changes from turbidity to clarification. The professionalism of phage parasitism is different. The parasitic range is multivalent phage, which can infect a variety of bacteria of the same genus; monovalent phage only infects the same kind of bacteria; extremely specialized phage even only for the same kind of bacteria A strain has invasive power, so it is possible to find a suitable specialized phage as a biological reagent for identifying various bacteria.
Cell wall component
The cell wall of Gram-positive bacteria contains more peptidoglycans and less lipids. Gram-negative bacteria are the opposite. The cell wall of Streptomyces contains alanine, glutamic acid, glycine and 2,6-aminopimelic acid, while the arabinose is characteristic of Nocardia. The mold cell wall mainly contains chitin.
Infrared absorption spectrum
Infrared absorption spectroscopy is used to determine the chemical composition of microbial cells and to understand the chemical properties of microorganisms as one of the classification criteria.
GC content
The material basis of biological inheritance is nucleic acid, and the similarities and differences in nucleic acid composition reflect the kinship between organisms. In the case of a biological DNA, its base sequence is fixed. By determining the mole percentage of guanine (G) and cytosine (C) in the four bases, it is possible to understand the degree of different origin of various microbial DNA molecules. Microorganisms with close phylogenetic relationships, the two microorganisms whose G+G content is the same or similar, are not necessarily closely related because the order of the four bases of their DNA is not necessarily the same.
DNA heterozygosity
To determine the genetic relationship between microorganisms, the base sequence of their DNA must be compared. The most common method is DNA hybridization. The basic principle is the reversibility of DNA melting and the specificity of base pairing. The DNA is extracted and melted, and the complementary bases are re-paired into a double strand. The hybridization rate can be measured based on the case where a double strand can be generated. The higher the heterozygosity rate, the higher the similarity of the base sequence between the two DNAs, and the closer the kinship between them.
Ribosomal ribose acid (rRNA) correlation
RRNA homologous properties show their genetic relationship between strains with low DNA correlation. The Rrna-DNA hybridization assay can determine the correlation of Rrna and reveal the homology of Rrna.
Base sequence of rRNA
The base sequence of RNA is transcribed from DNA, so it has a corresponding relationship. The 16S rRNA labeled in bacteria is extracted and isolated, and digested with ribonucleic acid to obtain various oligonucleotides. The base sequence on these oligonucleotides can be determined as a marker for bacterial taxonomy.
Composition analysis of ribosomal proteins
The 30S and 50S ribosomal protein subunits of the tested bacteria were isolated, and the types and contents of the ribosomal proteins contained therein were compared. The identified strains were divided into several groups, and a phylogenetic map was drawn.
Edit this section of the microbial classification system Here only a brief system of prokaryotic and eukaryotic microorganisms.
Prokaryotae
(1) Light energy nutrient prokaryotic gate
I Blue-green photosynthetic bacteria (cyanobacteria)
II red photosynthetic bacteria
III Green Photosynthetic Bacteria
(2) Chemical energy prokaryotes
I Bacterium
II rickettsia
III flexible membrane
IV archaea
Eucaryotic microbes
The true nuclear program mainly includes various fungi, as well as slime bacteria.
The basic principle of fungal classification of each energy classification unit is based on morphological characteristics, supplemented by physiological and biochemical, cytochemical and ecological characteristics. Filamentous fungi are mainly classified according to the method of spore production and the characteristics of the spore itself, as well as the culture characteristics. Identification, parasitism and symptoms of some pathogenic fungi can also be used as a reference. Fungi can be divided into the following four categories:
I The mycelium of the genus Algae is unseparated and contains multiple nuclei. Sexual reproduction forms oospores or spores.
The Ascomycetes mycelium is separated, and the ascospore spores are formed in the sexual stage.
III Basidiomycetes mycelium is separated, and the spores are formed in the sexual stage.
IV Deuteromycetes include all fungi that have only found a sexual stage in the asexual generation.
Myxobacteria can also be divided into four classes, namely
I. Myxomycetes protrudes from the ends of the cell with long sticky filaments and successively form a network of viscous masses - pseudo-mass.
II Myxobacteria secretes oxymycin to form a pseudogenic mass.
III Myxoplasma forms a syngenetic group, and saprophytic free life.
IV Rhizoctonia pathogens form the original mass, obligate parasitism. It is also attributed to fungi.
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