Chapter1  The introduction of microbiology

第1 章绪论

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.

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.

The importance of microbiology：

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.

2.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.

3.As a basic biological science：microorganisms are the best model systems for understanding basic life processes.
P All cells have much in common, what is true for E. coli is also true for elephant, only more so
P Simple yet representative
P Easiness and quickness to grow large quantity
Common characterizes of microorganism
•Big surface/volume

•High absorption and transformation

•Rapid growth and reproduction

•Easiness to variation

••high adaptation to environment

•Diversity 

Review question

1.Match the following people to their contribution toward the advancement of microbiology.

__ Ehrlich        (a) First to observe bacteria

__ Fleming        (b) First to observe cells in

__ Hooke            plant material and name

_ Koch             them

__ Lister         (c) Disproved spontaneous

__ Pasteur           generation

__ Van Leeuwenhoek  (d) Proved that microorganisms can cause disease

(e)      Discovered penicillin

(f)         Used the first syntheticchemotheraputic agent First to employ disinfectants in surgical procedures

2.  Match the following microorganisms to their descriptions.

__ Algae          (a) Not composed of cells

__ Bacteria       (b) Cell wall made of chitin

__ Fungi          (c) Cell wall made of

__ Protozoom          peptidoglycan

__ Viruses          (d) Cell wall made of cellulose; photosynthetic

 (e) Complex cell structure lacking a cell wall

3.Briefly state the role played by microorganisms in each of the following.

(a)      Biological control of pests

(b) Recycling of elements

(c)      Normal flora

(d) Sewage treatment

(e)      Human insulin production

4 The microbes were first formally observed in the mid-1600's, but the cell theory wasn't enunciated until 1839. Write a brief essay explaining why microbiology did not become a formally recognized science until Pasteur's time.

5. Compare and contrast the works of Louis Pasteur and Robert Koch, in terms of both applied and basic science.

6. 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.

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

7. 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.

●How did Pasteur´s famous experiment defeat the theory of spontaneous generation?

●How can Koch´s postulates prove cause and effect in a disease?

●Who was the first person to use solid culture media in microbiology?

●What advantages do solid media offer for the culture of microorganisms?

●What is the enrichment culture technique and why was it a useful new method in microbiology?