Chapter 1 The Main Themes of Microbiology

Chapter 1 The Main Themes of Microbiology

A. What is microbe? 
    The word microbe (microorganism) is used to describe an organism that is so small that, normally, it cannot be seen without the use of a microscope.
    Members of tile microbial world consist of three major groups: Eukaryote－fungoid、microscopic algae、protozoa and some intestinal parasitic worms; Prokaryote－bacteria、actinomycete、cyanobacteria and archaebacteria; Noncellular orgnism －virus, viroid and prion.

B. The characteristics of microorganism
1．Microscopic
2．independent units
3．less complex
4．rapid growth rates
5. opmipresent
6. Same research techniques

C. The position in life world and systematic taxa
    The categorizing system of biological five kindoms；The categorizing system of three domains.
    The systemic taxa of mocroorganisms follow the systemic taxa built by Linnaeus，including seven grades from top to bottom: Kingdom, Phylum, Class, Order, Family, Genus, Species. There are more than ten grades in the systemic taxa altogether, because each grade, if needed, could sub-divide some auxiliary units
    All species names of cellular microorganisms obey the Latin binominal nomenclature built by Linnaeus without exception，i.e. , a formal species name is built up by Latin words，and it should be italic. According to binomial nomenclature, a formal species name is consisting of a genus name and an adding word of a species. A formal species name present in taxology literature, namers often be added after them, but namers could be omitted generally.
    A formal species name should obey trinomial nomenclature, when the name of microorganism is a subspecies( sub-sp．, Roman type) or a variety (var., Roman type).

D. Research Area of microbiology
    Microbiology is a science of studying microorganisms, including diversity, activities rules of microorganisms and microbial contributions to the economic activities of human being.
    Microbiologists pursue careers in many areas, including universities, hospitals, public health departments, food and chemical industries, pharmaceutical companies, and environmental pollution agencies.

E. The importance and applications of microbiology
    1.Close correlation to the health of human beings and Animals. Many devastating diseases such as smallpox, bubonic plague and influenza have determined the course of history; "new" emerging diseases are arising in developed countries, which partly is because people are engaging in differentlifestyles and living in regions where formerly only animals lived; "old" diseases that were on the wane have begun to reemerge, many of which are brought to this country by people visiting foreign lands; several chronic diseases such as ulcers and perhaps even heart disease may be caused by bacteria; bacteria use the body as an ecological habitat and interact with other bacteria on its surface. Pathogens gain entrance to the body and find a protected habitat inside host ceils. Microorganisms produce medically important products and can produce vaccines against a variety of diseases.
    2. Wide applications in industrial productions. For thousands of years, bread, wine, beer, and cheeses have been made by using technology still applied today. Bacteria are being used to degrade dangerous toxic pollutants. Bacteria are used to synthesize a variety of different products, such as cellulose, hydroxybutyric acid, ethanol, antibiotics and amino acids.
    3. Great effect of microbe on agricultural productions.
    4. Acceleration development on biology. Microorganisms are excellent model organisms to study because they grow rapidly on simple, inexpensive media, but follow tile same genetic, metabolic, and biochemical principles as higher organisms. A bacterium can transfer genes into plants and modify their properties.

F. History of microbiology
    1.Perceptual knowledge phase（pro-history phase）
    2.Morphology description period (original period)
    Leenwennhoek’s description of bacteria by a special microscope
    3.Physiological research period foundation period
    Louis Pasteur:: negated abiogenesis drastically; proved ferment is reduced by microbe; Invented method of preparation street virus; attenuated vaccine; Invented pasteurization.
    Robert Koch: Invented medium and purified microbe using it; found pathogeny of anthracnose--anthrax bacillus; established Koch Law.
    4.Biochemistry research stage （development period）
    German scientist Eduard Buchner （1897）：fermented glucose to alcohol with yeast non-cellular extraction.
    English scientist Alexander Fleming （1929）：discovered the first antibiotics—penicillin in the world.
    5.molecular biology research stage （maturation phase）
    J.D.Waston and H.F.C.Crick（1953）: discovered DNA duplex model

G. Microbiology prospecting in 21century
    Having characteristics and commonness of vital phenomenon, microbe will be optimal material to solve significant theory problems and practical applications，such as origin and evolution of life, basic law of matter motion, exploitation of new microbial resources, energy resource and foodstuff etc. 

Koch's postulates：

Koch's postulates are a number of criteria that have been used in the past to prove that a bacterium is responsible for a particular disease.

1. The bacteria should be found in all cases and at all sites of the disease.

2. The bacteria should be isolated from the infected person and maintained in pure culture.

3. The pure cultured microbe should cause symptoms of the disease on inoculation into a susceptible individual.

4. The bacteria should be reisolated from the intentionally infected host.

Microbiology（微生物学）：Microbiology is specialized area of biology that deals with living things ordinarily too small to be seen with the naked eyes.

Microorganisms（微生物，microbe） ：Microorganisms are defined as the organisms that are so small that ，normally，it cannot be seen without the use of a mocriscope.

The word is therefore used to describe virus，bacreria，fungi，protozoom and some algae.

Bacteria（细菌）：Bacteria are some small，single celle organisms. Because they have no nucleus， the cells are described as prokaryotes.

Fungi（真菌）：Fungi （mushrooms（蘑菇）， molds（霉菌）， and yeasts） have eukaryotic（真核的） cells （with a true nucleus）。 Most fungi are multicellular.Fungi obtain nutrients by absorbing organic material from their environment.

Protozoom（原生动物）：Protozoans are unicellular eucaryotes and are classified according to their means of locomotion. Protozoans obtain nourishment by absorption or ingestion through specialized structures.

Algae（藻类）：Alage are unicellular or multicellular eukaryotes that obtain nourishment by photosynthesis.Algae produce oxygen and carbohydrates that are used by other organisms.

Viruses（病毒）：Viruses are noncellular entities that are parasites of cells. Viruses consist of a nucleic acid core （DNA or RNA） surrounded by a protein coat. An envelope may surround the coat.

A brief history of microbiology

The science of microbiology did not start until the invention of the microscope in the mid 16th century and it was not until the late 17th century that Antoine van Leeuwenhoek made their first records of fungi， bacteria and protozoa.

The late 19th century was the time when the first real breakthroughs on the role of microbes in the environment and medicine were made. Louis Pasteur disproved the theory of spontaneous generation（自然发生）（that living organisms spontaneously arose from inorganic material） and Robert Koch's development of pure culture techniques allowed him to show unequivocally that a bacterium was responsible for a particular disease. Since then the science has grown dramatically as microbiology impinges on all aspects of life and the environment.

1. Anton van leeuwenhoek， using a simple microscope，was the frist to observe microorganisms（1676）

2.  Louis Pasteur stated that microorganisms are in the air everywhere and offered proof of biogenesis

3. Louis Pasteurˊdiscoveries led to the developmemt of aseptic（无菌的）techniques used in laboratory and medical procedures to prevent contamination by microorangisms that are in the air.

4. Louis Pasteur found that yeast ferments（发酵） sugar to alchhol and that can oxidize alcohol to acetic acid.

5. A heating process called pasteurization（巴斯德消毒）is used to kill bacteria in some alcohol beverages and milks.

6. Joseph Lister introduced the use of a disinfectant（消毒） to clean surgical dressings in order to control infections in humans.

7. Robert Koch proved that microorganisms transmit diseases.He used a sequence of procedures called Koch's postulates（科赫法则），Which are used today to prove that a particular microorganism casues a particular disease.

Microbes in our body

1. Everyone has microorganisms in and on the body Some microorganisms live in humans and other animals and are needed to maintain the animals health. these make up the normal flora（正常菌群）；

2. Some Microorganisms cause disease；

3. The disease-producing properties of a species of microbe and the host's resistance are important factors in determining whether a person will contract a disease.

Microbes and Human Welfare

1. Microorganisms degrade dead plants and animals and recycle chemical elements to be used by living plants and animals.

2. Bacteria are used to decompose organic matter in sewage. Bioremediation processes use bacteria to clean up toxic wastes.

3. Bacteria that cause diseases in insects are being used as biological controls of insect pests. Biological controls are specific for the pest and do not harm the environment.

4. Using recombinant DNA， bacteria can produce important human proteins， such as insulin， beta-endorphin，and hepatitis B vaccine.Microorganisms can be used to help produce foods.They are also food sources （single-cell protein） themselves.

Questions:

1. How did Pasteur′s famous experiment defeat the theory of spontaneous generation？

2. How can Koch′s postulates prove cause and effect in a disease？

3. In what ways are microorganisms important in the food ， agriculture，and industries？

Microorganisms can be both beneficial and harmful to humans. Although we tend to emphasize the harmful microorganisms （infectious disease agents）， many more are beneficial than harmful.

Louis Pasteur′s work on spontaneous generation led to the development of methods for control of the growth of microorganisms. Robert Koch developed criteria for the study of infectious microorganisms， and developed the first methods for the growth of pure cultures of microorganisms. Beijerinck and Winogradsky studied bacteria in soil and water， and developed the enrichment culture technique. In the twentieth century， basic and applied microbiology have worked hand in hand to yield a number of important practical advances and a revolution in molecular biology.