Will bacteria be the last life on earth?

Scientists say that the last survivor of the future earth will be microorganisms.

According to British media reports, scientists believe that the last creatures on the earth will be microorganisms living deep underground, because as the sun gets hotter and brighter, only bacteria can survive under such extreme conditions.

Scientists from St Andrews University, university of dundee University and Edinburgh University predict that in the next 654.38 billion years, the sun will become very hot and the earth's oceans will begin to disappear.

Jack James of the University of St Andrews in Scotland said: "At this turning point, there is a lot of water in the atmosphere. Water vapor is a greenhouse gas, which will aggravate the greenhouse effect, and the temperature of the earth will rise to 100 degrees Celsius or even higher." "At the same time, with the decrease of oxygen, plants and large animals will disappear quickly."

Soon, a bacterium called extremophile will become the only life form left on the earth. This kind of microorganism now exists on the earth and can survive in harsh environment.

"At that time, there won't be much oxygen, so they need to live in an environment with low oxygen or no oxygen, and because seawater evaporates, they have high pressure and high salt." Jack James said.

But with the deterioration of living conditions, this kind of bacteria will eventually become extinct, and there will be no life on the earth after about 2.8 billion years.

Bacteria (English: germs; Scientific name: bacteria are prokaryotes in a broad sense, which refer to a large class of non-nuclear envelope of nuclei, only called nucleoid region (nucleus

Region) (or pseudonucleus), including eubacteria and archaea. What people usually call bacteria in a narrow sense is a kind of prokaryote, which is a kind of prokaryote with short body and simple structure, and often reproduces in a binary way. It is the most widely distributed creature with the largest number of individuals in nature, and it is the main participant in the natural material cycle.

People usually say that bacteria are bacteria in a narrow sense, and bacteria in a narrow sense are a kind of prokaryotes. They are slender and short in shape, simple in structure and multiply in a binary way. They are the most widely distributed creatures with the largest number of individuals in nature, and they are the main participants in the natural material cycle. The discoverer of bacteria is an Englishman Robert? Hook.

Bacteria are one of the main groups of organisms and belong to the field of bacteria. Bacteria are the most abundant of all living things, and its total number is estimated to be about 5× 10 to the thirtieth power. Bacteria are very small, the smallest known bacteria are only 0.2 micron long, so most bacteria can only be seen under a microscope. Bacteria are generally single-celled, with simple cell structure, lacking nucleus, cytoskeleton and membranous organelles, such as mitochondria and chloroplasts. According to these characteristics, bacteria belong to prokaryotes. There is another kind of organism in prokaryotes called archaea, which is a new category created by scientists according to their evolutionary relationship. For the sake of distinction, this creature is also called eubacteria.

Bacteria-classification

Except for a few archaea, most prokaryotes are true bacteria. It can be roughly divided into six kinds, namely bacteria (in a narrow sense), actinomycetes, cyanobacteria, mycoplasma, rickettsia and chlamydia.

According to its shape, it can be divided into three categories, namely cocci, bacilli and spirillus (including Vibrio, spirillus and spirillus).

According to the life style of bacteria, it can be divided into autotrophic bacteria and heterotrophic bacteria, among which heterotrophic bacteria include saprophytic bacteria and parasitic bacteria.

According to the oxygen demand of bacteria, they can be divided into aerobic (complete aerobic and mild aerobic) and anaerobic (incomplete anaerobic, aerobic tolerant and complete anaerobic) bacteria.

According to the survival temperature of bacteria, it can be divided into three categories: cold-loving, normal temperature and high temperature. The discoverer of bacteria: Dutch businessman Anthony Levinhook.

door

Aquaculture fungi

Thermophylum

Thermal desulfurization bacteria

Singular cocci, a phylum of abnormal cocci

A gold-producing bacterium

Chlorophylum; chlorophylum

Thermo-microorganism

Nitrifying spirillum; nitrifying spirillum

Iron-removing animals, iron-removing animals.

Cyanophyta

Chloramphenicol bismuth chloride

Proteus, Proteus

Thick-walled door

Actinomyces, actinomycetes

Plankton, a floating mold

chlamydia

Spirogyra of the genus Spirogyra

Fibrobacteria phylum

Acidosporium

Bacteroides

flavobacterium

Sphingosine bacteria of sphingolipids

Fusobacterium， Knorr 1922

Microbacteria verrucosa, a phylum of Microbacteria verrucosa.

Reticulate nematodes

Gemmatimonadettes, gemmatimonadettes gate

Bacterial distribution

Bacteria are widely distributed in soil and water, or live with other organisms. The human body also carries quite a lot of bacteria. It is estimated that the total number of bacterial cells in human body and epidermis is about ten times that of human body.

In addition, some species are distributed in extreme environments, such as hot springs and even radioactive waste. They are classified as extreme microorganisms, the most famous of which is Thermotogamaritima, which was discovered by scientists in Italy's submarine volcano. However, there are so many kinds of bacteria that scientists have only studied a few of them and named them. Of all the doors in the field of bacteria, only about half contain species that can be cultured in the laboratory. There are two nutritional modes of bacteria: autotrophic and heterotrophic, among which heterotrophic saprophytic bacteria are important decomposers in the ecosystem, which makes the carbon cycle go smoothly. Some bacteria will carry out nitrogen fixation to transform nitrogen into a form that can be used by organisms.

Bacteria (singular: bacteria) is one of the main groups of organisms and belongs to the field of bacteria. Bacteria are the largest group of all living things, with an estimated total of about

5× 1030. The individual of bacteria is very small, and the smallest known bacteria is only 0.2 micron long.

So most of them can only be seen under a microscope. Bacteria are generally single-celled, with simple cell structure, lacking nucleus, cytoskeleton and membranous organelles, such as mitochondria and chloroplasts. According to these characteristics, bacteria belong to prokaryotes. There is another kind of organism in prokaryotes called archaea, which is a new category created by scientists according to their evolutionary relationship. For the sake of distinction, this creature is also called eubacteria.

There are two ways of bacterial nutrition: autotrophic and heterotrophic, among which heterotrophic saprophytic bacteria are important decomposers in the ecosystem, which make the carbon cycle go smoothly. Some bacteria will carry out nitrogen fixation to transform nitrogen into a form that can be used by organisms. Bacteria also have a great influence on human activities. On the one hand, bacteria are the pathogens of many diseases, including tuberculosis, gonorrhea, anthrax, syphilis, plague and trachoma. However, human beings often use bacteria, such as the production of cheese, yogurt and fermented grains, the production of certain antibiotics, and the treatment of wastewater. These are all related to bacteria. Bacteria are widely used in biotechnology.

1 history

2 copy

3 metabolism

Four sports

Five forms

6 Taxonomy

6. 1 classification status

6.2 Classification of bacteria

7 Use and harm

Other 8 people

9 references

9. 1 reference

9.2 books

10 See Synonyms at 0

The term historical bacteria was first put forward by German scientist Ehrenberg in 1828 to refer to a certain kind of bacteria. This word comes from the Greek β α κ ρ ι ν, which means "small stick".

1866, German zoologist haeckel (Ernst

Haeckel, 1834- 19 19) suggested using "protozoa", including all unicellular organisms (bacteria, algae, fungi and protozoa).

1878, French surgeon Charles Emmanuel

Sedillot, 1804- 1883) proposed "microorganism" to describe bacterial cells or, more generally, tiny organisms.

Because bacteria are unicellular microorganisms, they are invisible to the naked eye and need to be observed with a microscope. 1683, Levin Hook (Anthony Van)

Leeuwenhoek (1632–1723) first observed bacteria with a self-designed Dan Toujing microscope with a magnification of about 200 times. Louis pasteur (Louis

Pasteur (1822- 1895) and robert koch (1843- 19 10) pointed out that bacteria can cause diseases.

Breeding bacteria can reproduce asexually or through gene recombination. The most important way is binary division, that is, the cell wall of a bacterial cell divides horizontally to form two daughter cells. And a single cell will also undergo genetic variation in the following ways: mutation (the genetic code of the cell itself changes randomly), transformation (unmodified DNA is transferred from one bacterium to another in solution), transfection (virus or bacterial DNA, or both DNA are transferred to another bacterium through phage), and bacterial conjugation (the DNA of one bacterium is transferred to another bacterium through a special protein structure formed between two bacteria). Bacteria can obtain DNA in these ways, then divide and pass on the recombinant genome to their offspring. Many bacteria contain plasmids containing extrachromosomal DNA.

When in a favorable environment, bacteria can form aggregates visible to the naked eye, such as colonies.

Bacteria spend a limited adverse environment in the form of spores, such as pasteurized (70-80 degrees Celsius) food can not last for a long time.

Metabolic bacteria have many different metabolic patterns. Some bacteria only need carbon dioxide as a carbon source and are called autotrophs. Those who get energy from light through photosynthesis are called photosynthetic autotrophs. Those who rely on oxidized compounds for energy are called chemoautotrophs. Other bacteria rely on organic carbon as carbon source, which is called heterotrophic bacteria.

Photosynthetic autotrophic bacteria, including cyanobacteria, are the oldest known organisms and may play an important role in producing oxygen in the earth's atmosphere. Other photosynthetic bacteria carry out some processes that do not produce oxygen. Include green sulfur bacteria, green non-sulfur bacteria, purple bacteria and sunlight bacteria.

Nutrients required for normal growth include nitrogen, sulfur, phosphorus, vitamins and metal elements such as sodium, potassium, calcium, magnesium, iron, zinc and cobalt.

According to their reaction to oxygen, most bacteria can be divided into the following three categories: some can only grow under aerobic conditions, called aerobic bacteria; Others can only grow under anaerobic conditions, called anaerobic bacteria; Some facultative anaerobic bacteria can grow under aerobic or anaerobic conditions. Bacteria can also thrive in extreme environments considered by human beings, and such creatures are called extremophile. Some bacteria exist in hot springs and are called thermophilic bacteria; Others live in high salt lakes and are called halophiles; Other bacteria exist in acidic or alkaline environment and are called acidophilic bacteria and alkalophilic bacteria. Others exist in alpine glaciers and are called psychrophilic bacteria.

Moving bacteria can move by flagella, bacteria sliding or changing buoyancy. Another kind of bacteria, spirochete, has some flagella-like structures called axoneme, which connect two cell membranes of periplasm. When they move, their bodies take on a twisted spiral shape. Spirillum has no axoneme, but flagella.

The flagella of bacteria are arranged in different ways. Bacteria can have a polar flagella at one end, or a cluster of flagella. Peripheric organisms have scattered flagella on their surfaces.

Sports bacteria can be attracted or repelled by specific stimuli, which is called chemotaxis, such as chemotaxis, phototaxis and mechanism. In a special kind of bacteria-myxobacteria, individual bacteria attract each other and gather together to form fruiting bodies.

form

germ

coccus

Spirillum

vibrio

The change of taxonomic classification status of bacteria fundamentally reflects the change of thinking in the development history, and many species even change or change their names frequently. In recent years, with the development of DNA sequencing, genomics, bioinformatics and computational biology, bacteriology has been placed in a suitable position.

At first, except cyanobacteria (not classified as bacteria at all, but as blue-green algae), other bacteria were considered as a kind of fungi. With the discovery of their special prokaryotic cell structure, which is obviously different from other organisms (they are all eukaryotes), bacteria are classified as a single species and called prokaryotes, bacteria and monera kingdom at different times. It is generally believed that eukaryotes are derived from prokaryotes.

By studying the rRNA sequence, American microbiologist Carl Woods (Carl

Woese) proposed in 1976 that prokaryotes include two groups. He called them eubacteria and archaea, and later renamed them bacteria and archaea. Woods pointed out that these two kinds of bacteria and eukaryotic cells are different species that originated from a primitive organism. Researchers have abandoned this model, but the three-domain system has gained universal recognition. In this way, bacteria can be divided into several fields, which are considered as one field in other systems. They are usually regarded as a single-source group, but this method is still controversial.

Classification of bacteria Bacteria can be classified in different ways. Bacteria have different shapes. Most bacteria are divided into the following three categories: bacilli are rod-shaped; The cocci are spherical (such as streptococcus or staphylococcus); Spirillum is spiral. The other is Vibrio, which is comma-shaped.

The structure of bacteria is very simple. Prokaryotes have no membrane organelles such as mitochondria and chloroplasts, but have cell walls. According to the composition of cell wall, bacteria can be divided into gram-positive bacteria and gram-negative bacteria. Gram comes from Danish bacteriologist Hans Christian Gram, who invented Gram staining.

Some bacteria have a capsule made of polysaccharide outside the cell wall, forming a cover or capsule. Capsules can help bacteria stay dormant in dry season, and can store food and dispose of waste.

Bacteria are both useful and harmful to the environment, human beings and animals. Some bacteria become pathogens, leading to tetanus, typhoid fever, pneumonia, syphilis, cholera, tuberculosis and even food poisoning. In plants, bacteria cause leaf spot, fire blight and wilting. Infection modes include contact, air transmission, food, water and microorganisms carrying bacteria. Pathogens can be treated with antibiotics and can be divided into bactericidal and bacteriostatic types. Generally speaking, about 80% of bacteria are harmless to people.

Bacteria are usually used in fermented food together with yeast and other kinds of fungi. For example, in the traditional manufacturing process of vinegar, acetic acid bacteria in the air are used to convert alcohol into vinegar. Other foods made by bacteria include cheese, pickles, soy sauce, vinegar, wine and yogurt [7][8]. Bacteria can also secrete a variety of antibiotics, for example, Streptomyces is secreted by Streptomyces [9].

The ability of bacteria to degrade many organic compounds is often used to remove pollution, which is called bioremediation.

)。 For example, scientists use methane-oxidizing bacteria to decompose trichloroethylene and tetrachloroethylene pollution in Georgia, USA [9].

Other bacteria are very old creatures, which appeared about 3.7 billion years ago.

Two kinds of organelles in eukaryotic cells, mitochondria and chloroplasts, are usually considered to be derived from endophytic bacteria.

Microorganisms are widely distributed in places with food, humidity and suitable temperature, which are suitable for their reproduction and growth. Bacteria can be carried from one place to another by airflow. The human body is the habitat of a large number of bacteria; It exists on the skin surface, intestines, mouth, nose and other body parts. They exist in the air we breathe, the water we drink and the food we eat.

Relevant information and pictures are all from the Internet: through Baidu search.

The sources of relevant reference materials are as follows:

Chinese international:/hqzx/2013-07/03/content _16710477.htm.

Baidu encyclopedia: /view/ 19 168.htm

Wikipedia, a free encyclopedia: /wiki/%E7%BB%86%E8%8F%8C