Species and distribution of microorganisms in the surrounding environment

Microorganisms are a large class of organisms, including bacteria, viruses, fungi and some small protozoa. Although small, it is closely related to people's lives. Microorganisms can be described as "ubiquitous, ubiquitous" in nature, covering a variety of beneficial and harmful, widely involving health, medicine, industry and agriculture, environmental protection and many other fields.

Prokaryotes: bacteria, actinomycetes, spirochetes, mycoplasma, rickettsia, chlamydia.

Eukaryotes: fungi, algae, protozoa.

Cell-free classes: viruses and subviruses.

Generally speaking, in Chinese mainland's textbooks, microorganisms are divided into the following eight categories: bacteria, viruses, fungi, actinomycetes, rickettsia, mycoplasma, chlamydia and spirochetes.

Definition of microorganism

The floorboard of all tiny creatures that are invisible or unclear to the naked eye.

Characteristics of 1: tiny and average.

Simple structure, single cell, simple multicellular and acellular.

Low evolutionary status.

Classification of prokaryotes: three bacteria, three bodies.

Eukaryotes: fungi, protozoa, microalgae.

Acellular class: virus, sub-virus (viroid, pseudovirus, prion)

Five characteristics: small size and large area.

The more absorbed, the faster the transformation.

It grows vigorously and reproduces rapidly.

Strong adaptability and easy to change

Widely distributed and diverse.

Second, the microbial community.

1 bacteria:

(1) Definition: A class of prokaryotes with short cells, simple structure, tough cell walls, dichotomous reproduction and strong aquatic properties.

(2) Distribution: warm and humid, rich in organic matter.

(3) Structure: It is mainly single-celled prokaryote, which is spherical, rod-shaped and spiral.

Cell epidermis

Basic structural cell membrane

cytoplasm

Structural quasi-nucleus

flagellum

Capsule with special structure

bud

(4) Reproduction: mainly in the form of binary fission.

(5) Colony: A single bacterium is invisible to the naked eye. When a single bacterium or a small number of bacteria multiply in solid medium, it will form a daughter cell community with a certain morphological structure that can be seen by the naked eye.

Colony is an important basis for strain identification. Different kinds of bacterial colonies are different in size, shape, luster, color, hardness, transparency and toxicity.

actinomyces

(1) Definition: A kind of terrestrial prokaryote that mainly grows in hyphae and reproduces by spores.

(2) Distribution: In weak alkaline soil with low water content and rich organic matter.

(3) Morphological structure: mainly composed of hyphae, including matrix hyphae and aerial hyphae (some aerial hyphae can mature and differentiate into sporophytes to produce spores).

(4) reproduction: asexual reproduction is carried out by forming asexual spores.

asexual reproduction

(5) Colony: on solid culture medium: dry, opaque, with velvet-dense surface and colored dry powder.

3 virus

(1) Definition: A kind of "acellular organism" which is composed of a few components such as nucleic acid and protein, but its survival depends on living cells.

(2) Structure:

(3) Size:

Generally, the diameter is about 100nm.

The largest virus is vaccinia virus, with a diameter of 200 nanometers.

The smallest virus is poliovirus, with a diameter of 28 nanometers.

(4) Proliferation: Take phage as an example:

Adsorption invasion, proliferation, assembly and release

Section 2 Microbial Nutrition

I. Chemical composition of microorganisms

Carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur and other elements.

Second, the nutritional components of microorganisms

1 water and inorganic salts

Carbon source: any nutrient that can provide carbon for the growth and reproduction of microorganisms.

source

function

Nitrogen source: any nutrient that can provide necessary nitrogen for microorganisms.

source

Function: Mainly used to synthesize protein, nucleic acid and nitrogen-containing metabolites.

Energy: nutrients or radiant energy that can provide the initial energy source for microbial life activities.

According to the classification of carbon sources and energy sources:

5 growth factor: trace organic matter indispensable for microbial growth

Microorganisms that can cause human and animal diseases are called pathogenic microorganisms. There are eight categories:

1. Fungi: cause skin diseases. Deep tissue infection.

Actinomycetes: skin and wound infections.

3 spirochete: skin diseases, blood infections such as syphilis and leptospirosis.

Bacteria: skin disease suppuration, upper respiratory tract infection, urinary tract infection, food poisoning, septicemia, acute infectious diseases, etc.

Rickettsia: typhus, etc.

Chlamydia: trachoma, urogenital infection.

Viruses: hepatitis, Japanese encephalitis, measles, AIDS, etc.

Mycoplasma: pneumonia, urinary tract infection.

There are thousands of kinds of microorganisms in the biological world, most of which are beneficial to human beings, and only a few can cause diseases. Some microorganisms are usually not pathogenic, but can cause infection under certain circumstances, which is called conditional pathogenic bacteria. It can cause food deterioration and corruption, and it is precisely because they decompose natural objects that the material cycle of nature can be completed.

Some people mistake fungi for bacteria, which is a common misunderstanding. Especially those who didn't receive systematic biology education before 1980s.

One of the most important effects of microorganisms on human beings is the prevalence of infectious diseases. 50% of human diseases are caused by viruses. According to the data published by the World Health Organization, the incidence and mortality of infectious diseases rank first among all diseases. The history of human diseases caused by microorganisms is also the history of human struggle against it. Great progress has been made in the prevention and treatment of diseases, but new and reappearing microbial infections continue to occur, for example, a large number of viral diseases have been lacking effective therapeutic drugs. The pathogenesis of some diseases is still unclear. The abuse of a large number of broad-spectrum antibiotics has caused strong selection pressure, which has caused many strains to mutate and produce drug resistance, posing a new threat to human health. Some segmental viruses can mutate through recombination or rearrangement, and the most typical example is influenza virus. Every time an outbreak of influenza occurs, the influenza virus will mutate from the strain that caused the infection last time. This rapid mutation has caused great obstacles to the design and treatment of vaccines. The emergence of drug-resistant mycobacterium tuberculosis has made the tuberculosis infection that was almost controlled rampant in the world.

There are many kinds of microorganisms, some of which are corrupt, that is, they cause bad changes in food odor and tissue structure. Of course, some microorganisms are beneficial. They can be used to produce cheese, bread, pickles, beer and wine. Microorganisms are so small that they must be magnified with a microscope to see them. For example, for medium-sized bacteria, 1000 is only as big as a period. Imagine a drop of milk, there are about 50 million bacteria in every milliliter of rotten milk, or the total number of bacteria in every quart of milk is about 5 billion. That is, a drop of milk can contain 5 billion bacteria.

Microorganisms can cause diseases, which will cause food, cloth, leather and other moldy rot, but microorganisms also have a beneficial side. It was Fleming who first discovered penicillin from Penicillium which inhibited the growth of other bacteria, which was an epoch-making discovery in the medical field. Later, a large number of antibiotics were screened from the metabolites of actinomycetes. The use of antibiotics saved countless lives in World War II. Some microorganisms are widely used in industrial fermentation to produce ethanol, food and various enzyme preparations. Some microorganisms can degrade plastics and treat wastewater and waste gas. , and has great potential of renewable resources, known as environmental microorganisms; Some microorganisms can survive in extreme environments such as high temperature, low temperature, high salt, high alkali and high radiation, and some microorganisms still exist. It seems that many microorganisms have been discovered, but in fact, due to the limitation of technical means such as culture methods, the microorganisms discovered by human beings today only account for a small part of the existing microorganisms in nature.

The interaction mechanism between microorganisms is also quite mysterious. For example, there are a large number of bacteria in the intestines of healthy people, which are called normal flora, including hundreds of bacteria. In the intestinal environment, these bacteria are interdependent and mutually beneficial. The decomposition and absorption of food, toxic substances and even drugs, the role of flora in these processes and the interaction mechanism between bacteria are still unknown. Once the flora is out of balance, it will cause diarrhea.

With the medical research entering the molecular level, people are more and more familiar with the technical terms such as genes and genetic materials. It is recognized that genetic information determines the life characteristics of organisms, including external morphology and life activities, and the genome of organisms is the carrier of these genetic information. Therefore, understanding the genetic information carried by the genome of an organism will be of great help to reveal the origin and mystery of life. It is a revolution to study the variation, virulence and pathogenicity of microbial pathogens at the molecular level.

Biological genome research represented by the Human Genome Project has become the frontier of the whole life science research, and microbial genome research is an important branch. Science, an authoritative magazine in the world, once rated microbial genome research as one of the major scientific advances in the world. Revealing the genetic mechanism of microorganisms through genome research, discovering important functional genes, and developing vaccines and new antiviral, antibacterial and antifungal drugs on this basis will effectively control the epidemic of old and new infectious diseases and promote the rapid development and growth of medical and health undertakings!

Studying the genome of microorganisms at the molecular level provides new clues and ideas for exploring the mystery of the interaction between individuals and groups of microorganisms. In order to fully develop microbial (especially bacterial) resources, the United States launched the Microbial Genome Research Program (MGP)65438-0994. By studying the complete genome information, we can not only deepen our understanding of the pathogenic mechanism, important metabolism and regulation mechanism of microorganisms, but also develop a series of genetic engineering products closely related to our lives, including vaccination vaccines, therapeutic drugs, diagnostic reagents and various enzyme preparations applied to industrial and agricultural production. Through the transformation of genetic engineering methods, we will promote the construction of new strains and the transformation of traditional strains, and comprehensively promote the era of microbial industry.

Industrial microorganisms involve food, pharmacy, metallurgy, mining, petroleum, leather, light chemical industry and many other industries. Production of antibiotics, butanol, vitamin C and preparation of some flavor foods by microbial fermentation; Some special microbial enzymes are involved in leather depilation, metallurgy, oil extraction and mining, and even directly used as additives for washing powder. In addition, some microbial metabolites can be widely used in agricultural production as natural microbial pesticides. By studying the genome of Bacillus subtilis, a series of genes related to the production of antibiotics and important industrial enzymes were found. As an important microecological regulator, lactic acid bacteria participate in the food fermentation process. Genomic research on lactic acid bacteria will help to find key functional genes, and then transform the strain to make it more suitable for industrial production. The genome research of Gluconobacter oxydans, the key strain in the two-step fermentation process of vitamin C in China, will find important metabolic functional genes related to vitamin C production on the premise of genome sequencing, and realize the construction of new engineering strains through genetic engineering transformation, simplify production steps, reduce production costs, and then greatly improve economic benefits. The genome research of industrial microorganisms has continuously found new special enzyme genes and functional genes related to important metabolic processes and metabolites, and applied them to production and the transformation of traditional industries and processes, which has promoted the rapid development of modern biotechnology.

Understand the pathogenic mechanism of agricultural microbial genome research and develop new countermeasures to control diseases

According to statistics, the annual crop yield reduction caused by diseases in the world can be as high as 20%, among which plant bacterial diseases are the most serious. There seems to be no better disease control strategy except cultivating gene-resistant varieties and strengthening horticultural management. Therefore, it is very urgent to actively carry out genome research of some plant pathogenic microorganisms, understand their pathogenic mechanism and develop new countermeasures to prevent and control diseases.

The pathogen of commercial crop citrus is the first plant pathogenic microorganism in the world to publish its full sequence. There are also some agricultural microorganisms that are very important in taxonomy, physiology and economic value, such as Erwinia carrot, Pseudomonas spp. and Xanthomonas spp., which are being studied in China. Recently, the complete sequence of nitrogen-fixing rhizobia in plants has just been determined. Drawing on the mature scheme of screening therapeutic drugs from the genome information of human pathogenic microorganisms, it can be tentatively applied to plant pathogens. Especially citrus pathogens need insect vectors to complete their life cycle. Only by finding virulence-related factors and resistance targets through genetic research can more effective control strategies be formulated. The analysis of all genetic information of nitrogen-fixing bacteria is also of great significance for developing and utilizing its key nitrogen-fixing genes and improving crop yield and quality.

The research of environmental microbial genome found the key genes to degrade different pollutants.

While promoting economic development in an all-round way, the phenomenon of abusing resources and destroying the environment is becoming more and more serious. Facing the repeated deterioration of the global environment, advocating environmental protection has become the unanimous voice of people all over the world. Biological decontamination has great potential in environmental pollution control, and microbial participation in governance is the mainstream of biological decontamination. Microorganisms can degrade plastics, toluene and other organic substances; It can also treat industrial wastewater, sulfur-containing waste gas and phosphate in soil improvement. Microorganisms can decompose cellulose and other substances and promote the recycling of resources. On the premise of understanding the genetic background of special metabolic process, we can selectively use the genome research of these microorganisms, such as finding the key genes that degrade different pollutants, combining them in a certain strain, and constructing an efficient genetic engineering strain, which can degrade different environmental pollutants at the same time and greatly exert its potential of improving the environment and eliminating pollution. The American Genome Institute combined with biochip method to study the expression profile of microorganisms under special conditions in order to find the key genes that degrade organic matter and set the goal of development and utilization.

The study of microbial genome in extreme environment has great potential for understanding the nature of life.

Microorganisms that can grow in extreme environments are called extremophiles, also known as extremophiles. Extreme microorganisms have strong adaptability to extreme environments. The study of extreme microbial genome is helpful to study the adaptability of microorganisms under extreme conditions at the molecular level and deepen the understanding of the nature of life.

There is an extreme microorganism that can survive at thousands of times of radiation intensity, while humans will die at a dose intensity. The chromosome of bacteria is smashed into hundreds of pieces after receiving millions of radar rays, but it can be recovered within one day. It is of great significance to study its DNA repair mechanism for the development of environmental biological control in radiation-polluted areas. Exploiting and utilizing the extreme characteristics of extreme microorganisms can break through some limitations in the current biotechnology field, establish new technical means, and revolutionize the biotechnology capabilities in the fields of environment, energy, agriculture, health and light chemical industry. Extreme enzymes from extreme microorganisms can play a role in extreme environment, which will greatly expand the application space of enzymes and is the basis for establishing efficient and low-cost biotechnology processing, such as TagDNA polymerase in PCR technology and alkaline enzyme in detergent. The research and application of extremophiles will be an important way to gain the advantages of modern biotechnology, and its application potential in new enzymes, new drug development and environmental remediation is huge.

The position of microorganism in the whole life world!

Before human beings discovered and studied microorganisms, all living things were divided into two completely different worlds-the animal kingdom and the plant kingdom. With the gradual deepening of people's understanding of microorganisms, they have experienced three-realm system, four-realm system, five-realm system and even six-realm system from the two-realm system. Until the end of 1970s, American Woese and others discovered the third life form on earth-archaea, which led to the birth of the theory of three realms of life. According to this theory, life is composed of archaea, bacteria and eukaryotes. In the illustrated phylogenetic tree, the yellow branch on the left is the bacterial domain; The brown and purple branches in the middle are archaea; The green branch on the right is the eukaryotic domain.

Archaea includes Archaea, Archaea and Archaea. Bacterial domains include bacteria, actinomycetes, cyanobacteria and various other prokaryotes except archaea; Eukaryotic domain includes fungi, protozoa, animals and plants. Except for animals and plants, most other organisms belong to the category of microorganisms. It can be seen that microorganisms occupy a particularly important position in the classification of biology.

Life evolution has always been the focus of attention. According to the evolutionary tree of "Cenancestor" constructed by parallel homologous genes, Brown thinks that Cenancestor, the ancestor of life, is a protozoan. Protozoa have produced two branches in the process of evolution, one is prokaryote (bacteria and archaea) and the other is prokaryote. In the subsequent evolution process, bacteria and archaea first evolved in different directions, and then prokaryotes swallowed an archaea and replaced the host RNA genome with archaea DNA, resulting in eukaryotes.

From an evolutionary point of view, microorganisms are the old-timers of all living things. If the age of the earth is compared to one year, microbes will be born on March 20th, and humans will appear on the earth around 7 pm on February 3rd/kloc-0.