Microorganisms (microorganism referred to as microbe) are a large group of organisms, including bacteria, viruses, fungi and some small protozoa, etc. It is a tiny individual, but it is closely related to human life. Microorganisms in the natural world can be said to be "ubiquitous, everywhere", covering a wide range of beneficial and harmful species, widely involved in health, medicine, industry and agriculture, environmental protection and many other fields.
Prokaryotes: bacteria, actinomycetes, spirochetes, mycoplasma, rickettsiae, chlamydia.
Eukaryotic: fungi, algae, protozoa.
Noncellular: viruses and subviruses.
Microorganisms are generally categorized in textbooks in mainland China as follows: bacteria, viruses, fungi, actinomycetes, rickettsiae, mycoplasmas, chlamydiae, and spirochetes.
Definition of microorganisms
The general term for all microscopic organisms that are invisible to the naked eye or cannot be seen
1 Characteristics: tiny, generally <0.1mm.
Simple structure, unicellular, simple multicellular, non-cellular
Evolutionary status is low.
2 Classification Prokaryotes: trichobacteria, trisomes.
Eukaryotes: fungi, protozoa, microalgae.
Non-cellular: viruses, subviruses ( virus-like, mimetic viruses, prions)
3 five major **** sex: small size, large area
absorption, fast transformation
growth, reproduction
adaptable, easy to mutate
wide distribution, many kinds of
second, microbial groups
1 Bacteria:
(1)Definition: a class of prokaryotic organisms with short cells, simple structure, tough cell walls, reproduction by dictyostelium and strong aquatic organisms
(2)Distribution: warm, moist and organic matter-rich places
(3)Structure: mainly unicellular prokaryotic organisms, spherical, rod-shaped, spiral
cell wall
Basic structure cell membraneCytoplasm
Structure Nucleus
Flagellum
Special structure pods
Budding spores
(4)Reproduction: Mainly in the form of dictyostelium
(5)Colonies: A single bacterium can not be seen with the naked eye, but when a single or a small number of bacteria in the solid medium ah line, it will be a large number of bacteria. When a single or a small number of bacteria in the solid medium, a large number of propagation, will form a visible, with a certain form of structure of the daughter cell community.
The colony is an important basis for strain identification. The size, shape, gloss, color, hardness, transparency and toxicity of different types of bacterial colonies are different.
2 Actinomycetes
(1)Definition: a class of mainly mycelial growth and spore reproduction of terrestrial prokaryotic organisms
(2)Distribution: low water content, rich in organic matter, slightly alkaline soil
(3)Morphological structure: mainly composed of mycelium, including basidiomycetes and aerial mycelium (part of the aerial mycelium can be differentiated into sporocarps). (some aerial hyphae can mature and differentiate into spore filaments to produce spores)
(4)Reproduction: asexual reproduction through the formation of asexual spores
Asexual reproduction Asexual reproduction
(5)Colonies: on solid medium: dry, opaque, dense velvety surface, colorful dry powder
3 Virus
(1) Definition: a group of viruses that are composed of a few components, such as nucleic acids and proteins, but also of a number of other viruses. A class of "non-cellular organisms" consisting of a few components, such as nucleic acids and proteins, but which must depend on living cells for their survival.
(2) Structure:
(3) Size:
General diameter is about 100nm
The largest virus is cowpox virus with a diameter of 200nm
The smallest is poliovirus with a diameter of 28nm
(4) Proliferation:
The phage is an example of phagosome:
Adsorption, invasion, proliferation, and release
Assembling, release
Adaptation, invasion, proliferation. Assembly Release
Section 2: Nutrition of Microorganisms
I. Chemical Composition of Microorganisms
C,H,O,N,P,S, and Other Elements
II. Nutrients for Microorganisms
1 Water and Inorganic Salts
2 Carbon Sources: Any nutrients that provide microorganisms with the carbon necessary for growth and reproduction
Sources of Microorganisms
Source of Microorganisms
Source of Microorganisms
Source of Microorganisms
Source
Role
3 Nitrogen source: Any nutrient that provides microorganisms with essential nitrogen
Source
Role: Mainly used for the synthesis of proteins, nucleic acids, and nitrogen-containing metabolites
4 Energy source: Nutrients or radiant energy that provide an initial source of energy for microbial life activities
Based on the classification of carbon and energy sources. and energy source classification:
5 Growth factors: microorganisms indispensable for microbial growth of trace organic matter
Microorganisms that can cause disease in humans and animals are called pathogenic microorganisms, and there are eight major categories:
1. Fungi: cause skin diseases. Infections on deep tissues.
2 Actinomycetes:Skin, wound infections.
3 Spirochetes: skin diseases, blood infections e.g. syphilis, leptospirosis.
4 Bacteria: skin diseases, pus, upper respiratory tract infections, urinary tract infections, food poisoning, septicemia, acute infectious diseases.
5 Rickettsia: typhus and so on.
6 Chlamydia: trachoma, genitourinary tract infections.
7 Viruses: hepatitis, encephalitis B, measles, AIDS, etc.
8 Mycoplasma: pneumonia, urinary tract infections.
There are tens of thousands of microorganisms in the living world, most of which are beneficial to human beings and only a few of which can cause disease. Some microorganisms are not usually pathogenic, but can cause infections in certain environments, called conditionally pathogenic bacteria. Some microorganisms can cause food spoilage and corruption because they break down natural objects to complete the cycle of nature.
Some people mistake fungi for bacteria, a relatively common misunderstanding. This is especially true for those who were not educated in systematic biology before the 1980s.
One of the most important effects of microorganisms on human beings is to cause epidemics of infectious diseases. Fifty percent of human diseases are caused by viruses. The World Health Organization publishes information showing that infectious diseases occupy the first place among all diseases in terms of morbidity and mortality. The history of microorganisms causing human diseases is also the history of the constant struggle against them. In the prevention and treatment of disease, mankind has made great progress, but new and emerging microbial infections are still occurring, such as a large number of viral diseases have been the lack of effective therapeutic drugs. The causative mechanisms of some diseases are not well understood. The misuse of large quantities of broad-spectrum antibiotics has created strong selective pressures that have led to the mutation of many strains, resulting in the development of drug resistance and new threats to human health. Mutations can occur between some segmented viruses by recombination or reassortment, the prime example being influenza viruses. Each influenza pandemic influenza virus has mutated from the previous strain that caused the infection, and this rapid mutation creates a major obstacle to vaccine design and therapy. And the emergence of drug-resistant Mycobacterium tuberculosis has brought tuberculosis infections, which had been nearly under control, back to the forefront worldwide.
Microbes come in all shapes and sizes, and some are spoilage agents, causing undesirable changes in the odor and organization of food. Some microbes are beneficial, of course, and they can be used to produce such things as cheese, bread, sauerkraut, beer and wine. Microorganisms are so small that they can only be seen through a microscope at a magnification of about 1,000 times. A medium-sized bacterium, for example, is the size of a period when stacked 1,000 on top of each other. Imagine a drop of milk. There are about 50 million bacteria per milliliter of spoiled milk, or about 5 billion bacteria per quart of milk. That's 5 billion bacteria in a drop of milk.
Microorganisms can cause disease and mold and rotting of food, cloth, leather, etc., but they also have a beneficial side. It was Fleming who first discovered penicillin from the inhibition of other bacteria by Penicillium, which was an epoch-making discovery for the medical profession. Later a large number of antibiotics were screened from the metabolites of actinomycetes and other bacteria. The use of antibiotics saved countless lives in World War II. Some microorganisms are widely used in industrial fermentation, the production of ethanol, food and a variety of enzyme preparations, etc.; part of the microorganisms are able to degrade plastics, treatment of wastewater waste gas, etc., and the potential for renewable resources is great, known as the environmental protection microorganisms; there are also microorganisms that can survive in extreme environments, such as: high and low temperatures, high salt, high alkali, and high radiation and other ordinary life-forms can not survive in the environment, but still there is a part of microorganisms. Some microorganisms still exist. It seems that we have discovered a lot of microorganisms, but in fact, due to the culture method and other technical means of limitation, human beings nowadays discovered microorganisms still account for only a small part of the microorganisms existing in nature.
The mechanism of microbial interactions is also quite mysterious. For example, a large number of bacteria, called the normal flora, exist in the intestinal tract of a healthy person, which contains hundreds of bacterial species. In the intestinal environment these bacteria are interdependent, reciprocal **** born. Decomposition and absorption of food, toxic substances and even drugs, the role played by the flora in these processes, as well as the mechanism of bacterial interaction is not yet known. Once the flora is out of balance, diarrhea can be caused.
With medical research entering the molecular level, people are becoming more familiar with terminology such as genes and genetic material. People realize that it is the genetic information that determines the life characteristics of an organism, including its external form and the life activities it engages in, etc., and the genome of an organism is the carrier of this genetic information. Therefore, elucidating the genetic information carried by the genome of an organism will greatly help to reveal the origin and mystery of life. The study of the variation patterns, virulence and pathogenicity of microbial pathogens at the molecular level is a revolution for traditional microbiology.
The genome research of organisms represented by the Human Genome Project has become the frontier of the whole life science research, and microbial genome research is an important branch of it. The world's authoritative magazine "Science" has named microbial genome research as one of the world's major scientific advances. Through genome research to reveal the genetic mechanism of microorganisms, discover important functional genes and on this basis to develop vaccines, the development of new types of antiviral, antibacterial, fungal drugs, will be effective in controlling the prevalence of new and old infectious diseases, and to promote the rapid development of medical and health care and the growth of the cause!
Genomic studies of microorganisms at the molecular level provide new clues and ideas for exploring the mysteries of microbial individuals as well as intergroup roles. In order to fully develop microbial (especially bacterial) resources, the Microbial Genome Research Program (MGP) was initiated in the United States in 1994. Through the study of the complete genome information development and utilization of microorganisms important functional genes, not only can deepen the understanding of microbial pathogenesis, important metabolism and regulatory mechanisms, but also on the basis of the development of a series of closely related to our lives, genetic engineering products, including: vaccines, therapeutic drugs, diagnostic reagents, and a variety of enzyme preparations for industrial and agricultural production. Through the transformation of genetic engineering methods, we can promote the construction of new strains and the transformation of traditional strains, and comprehensively promote the microbial industry era.
Industrial microorganisms are involved in a variety of industries such as food, pharmaceuticals, metallurgy, mining, petroleum, leather, light chemicals and so on. Through the microbial fermentation pathway production of antibiotics, butanol, vitamin C, as well as the preparation of some flavored foods; some special microbial enzymes involved in leather hair removal, metallurgy, oil mining and other production processes, and even directly as a laundry detergent additives; in addition there are a number of microbial metabolites can be used as a natural microbial pesticides widely used in agricultural production. Through the genomic study of Bacillus subtilis, a series of genes related to the production of antibiotics and important industrial enzymes have been found. The genomic study of Lactobacillus as an important microecological regulator involved in the food fermentation process will be helpful to find the key functional genes, and then modify the strain to make it more suitable for the industrialized production process. The genomic study of Bacillus oxidans glucosinolates, a key strain in the two-step fermentation process of vitamin C production in China, will find the important metabolic function genes related to vitamin C production under the premise of completing genome sequencing, and then genetically engineered to realize the construction of new engineered strains, which will simplify the production steps, reduce the production cost, and then realize the substantial improvement of economic benefits. Genomic research carried out on industrial microorganisms, constantly discovering new special enzyme genes and important metabolic processes and metabolite generation-related functional genes, and applying them to the production as well as the transformation of traditional industries and processes, as well as promoting the rapid development of modern biotechnology.
Agricultural microbial genome research to recognize the disease-causing mechanism to develop new countermeasures to control disease
According to statistics, the global crop yield loss due to disease can be as high as 20% per year, of which bacterial diseases of plants are the most serious. There seems to be no better strategy for disease control than cultivating genetically resistant varieties and strengthening horticultural management. Therefore, it is urgent to actively conduct genomic research on certain plant disease-causing microorganisms in order to identify their disease-causing mechanisms and develop new disease-control strategies.
The causative agent of the cash crop citrus is the first plant pathogenic microorganism for which a full sequence has been published internationally. There are also a number of agricultural microorganisms that are very important taxonomically, physiologically and economically, such as Owen's bacillus of carrots, plant-pathogenic Pseudomonas aeruginosa, and Xanthomonas aeruginosa, which are being studied in China, that are in the process of development. Recently, the full sequence of nitrogen-fixing rhizobia has just been determined. The well-established program of screening therapeutic drugs from genomic information of human pathogenic microorganisms can be applied to plant pathogens in an experimental manner. In particular, for species such as citrus pathogens that require insect vectors to complete their life cycle, genetic studies can only be used to find virulence-related factors and resistance targets to develop more effective control measures, except for insecticides that can interrupt their life cycle. The analysis of all the genetic information of nitrogen-fixing bacteria is also of great significance for the development and utilization of their nitrogen-fixing key genes to improve the yield and quality of crops.
Environmental protection microbial genome study identifies key genes to degrade different pollutants
While economic development is advancing in all aspects, the misuse of resources and the destruction of the environment are becoming more and more serious. In the face of the repeated deterioration of the global environment, the promotion of environmental protection has become the people of the world **** the same call. And biological decontamination in environmental pollution management has great potential, microbial participation in the management is the mainstream of biological decontamination. Microorganisms can degrade plastics, toluene and other organic matter; also can deal with industrial wastewater phosphate, sulfur-containing waste gas and soil improvement. Microorganisms are able to decompose substances such as cellulose and promote the regeneration of resources. Genomic research on these microorganisms, in-depth understanding of the genetic background of special metabolic processes under the premise of selective utilization, such as finding the key genes for the degradation of different pollutants, will be combined in a strain, the construction of high-efficiency genetic engineering strains, a bacterium multi-purpose, can be degraded at the same time different environmental pollutants, and greatly exert its potential to improve the environment and eliminate pollution. The American Institute for Genomic Research (AIGR) has combined the biochip method to study the expression profiles of microorganisms under special conditions, with a view to finding their key genes for degrading organic matter, and setting targets for development and utilization.
Microbial genomic research in extreme environments provides insight into the nature of life with great potential for application
Microorganisms that can grow in extreme environments are called extremophiles, or extremophiles. Extremophiles are highly adaptable to extreme environments, and research on the genomes of extreme microorganisms can help study the adaptability of microorganisms under extreme conditions at the molecular level and deepen the understanding of the nature of life.
There is an extremophile bacterium that can survive exposure to thousands of times the intensity of radiation, whereas a single dose of human intensity would kill it. The bacterium's chromosomes shattered into hundreds of fragments after being exposed to millions of radsa radiation, but were able to restore them within a day. The study of its DNA repair mechanism is of great interest for the development of biological management of the environment in radiation-contaminated areas. Exploiting the extreme properties of extremophiles can break through some of the current limitations in the field of biotechnology and establish new technological means to revolutionize the biotechnological capabilities in the fields of environment, energy, agriculture, health, and light chemicals. Extreme enzymes from extreme microorganisms, which can exercise their functions in extreme environments, will greatly expand the application space of enzymes, and are the basis for the establishment of high-efficiency and low-cost biotechnological processes, such as TagDNA polymerase in PCR technology and alkaline enzyme in detergents, etc., all of which are of representative significance. The research and application of extreme microorganisms will be an important way to obtain the advantages of modern biotechnology, and its application potential in the development of new enzymes, new drugs and environmental remediation is great.
Microorganisms in the whole world of life!
When human beings before the discovery and study of microorganisms, all living things are divided into two distinct worlds - the animal world and the plant world. With the gradual deepening of people's understanding of microorganisms, from the two-world system through the three-world system, the four-world system, the five-world system and even the six-world system, until the late 1970s, the Americans, such as Woese, discovered the third form of life on the earth-archaea, which led to the birth of the three-domain doctrine of life. This theory is that life is composed of Archaea, Bacteria and Eucarya. In the "Phylogenetic Tree of Organisms" shown in the figure, the yellow branches on the left are the Bacteria domain; the brown and purple branches in the center are the Archaea domain; and the green branches on the right are the Eucarya domain.
The Archaea domain includes Crenarchaeota, Euryarchaeota, and Korarchaeota; the Bacteria domain includes Bacteria, Actinomycetes, Cyanobacteria, and a variety of prokaryotic organisms other than Archaea; and the Eukarya domain includes Fungi, Protozoa, Animals, and Plants. Except for animals and plants, most other organisms belong to the domain of microorganisms. This shows that microorganisms occupy a special and important position in the classification of organisms.
The evolution of life has always been a hotspot of people's attention. Brown et al. based on parallel homologous genes to construct the "Cenancestor" evolutionary tree of life, that the life of the *** with the ancestor of the Cenancestor is a protozoa. In the process of evolution, the protoorganism produced two branches, a prokaryote (bacteria and archaea) and a proto-eukaryote. In the subsequent evolutionary process, the bacteria and archaea first evolved in different directions, and then the proto-eukaryote swallowed an archaea, and the DNA of the archaea replaced the host's RNA genome, resulting in the emergence of a eukaryote.
From an evolutionary perspective, microorganisms are the oldest of all living things. If you compare the age of the Earth to a year, microbes were born around March 20, and humans appeared on Earth around December 31 at around 7pm.