Download 3.As a basic biological science：microorganisms are the best model

《微生物学》双语教学
授课教案
授课教师：李淑彬
华南师范大学生命科学学院
2003.2
1
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.
2. Louis Pasteur stated that microorganisms are in the air everywhere and offered proof of
biogenesisLouis 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.Louis Pasteur found that yeast ferments（发酵） sugar
to alchhol and that can oxidize alcohol to acetic acid.A heating process called
pasteurization（巴斯德消毒）is used to kill bacteria in some alcohol beverages and
milks.Joseph Lister introduced the use of a disinfectant（消毒） to clean surgical dressings
in order to control infections in humans.Robert Koch proved that microorganisms transmit
diseases.He used a sequence of procedures called Koch’s postulates（科赫法则）,Which are
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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.
 All cells have much in common, what is true for E. coli is also true for elephant, only more
so
 Simple yet representative
 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
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•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
_ Koch
__ Lister
plant material and name
them
(c) Disproved spontaneous
__ Pasteur
__ Van Leeuwenhoek
generation
(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
__ Viruses
peptidoglycan
(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?
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●What is the enrichment culture technique and why was it a useful new method in
microbiology?
Chapter 2 prokayotic microorganism(原核微生物)第二章
原核微生物
prokaryotic cells
The chief distinguishing characteristics of procaryotic cells are:
1.
genetic material (DNA) is not enclosed within a membrane.
2.
They lack other membrane bounded organelles.
3.
Their DNA is not associated with histone proteins (special chromosomal
proteins found in eucaryotes).Their cell walls almost always contain the
complex polysaccharide peptidoglycan （ 肽 聚 糖 ） .Bacteria( 细 菌 ) and
archaeobacteria（古细菌）
Bacteria are small, single-celled, microorganisms that belong to a group called prokaryotes .
Bacteria are ubiquitous. They are a highly successful and diverse group of organisms that can
obtain energy and carbon from a wide range of sources and therefore can colonize every niche on
our planet from deep ocean trenches to volcanic craters. In the 1970s, using DNA sequencing
information, it was found that the group we know as the bacteria could be split into two, the
eubacteria and the archaeobacteria and it appears that these two groups evolved away
from each other very early in the history of living things at about the same time that the
first group of eukaryotic cells evolved. Members of the eubacteria include some of the more
familiar bacteria such as Escherichia colt（ 大肠埃希氏菌） and Staphylococcus aureus（金
黄 色 葡 萄 球 菌 ） and are the prokaryotes that are best studied and understood. The
archaebacteria are a very diverse group of organisms, which differ from the eubacteria（真细
菌 0 in a number of features having, in particular, very different cell walls and membranes.
This group includes bacteria that are capable of existing in extreme environments 。
Size, Shape, and Arrangement of Bacterial Cells
1
Most bacteria are from 0.20 to 2.0 /µm in diameter and from 2 to 8µm in length.
2
The three basic bacterial shapes are coccus(spheres), bacillus(rods),and spiral (twisted).
3
In addition to the three basic shapes, there are star-shaped cells (genus Stella) and
recently discovered square, flat cells (halophilic( 嗜 盐 的 ) archaeobacteria) and
triangular cells (Haloarcula)
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the shape of a bacterium is determined by heredity.However, a number of
environmental conditions can alter that shape. Pleomorphic(多型性的) bacteria can
assume several shapes.
Gram Stain：
The eubacteria are frequently divided into two groups on the basis of their reaction to a stain
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devised by Christian Cram in 1884. The differential reaction to the staining procedure is
because of the structure of the cell wall in these two groups of bacteria. Gram-positive bacteria
have a single membrane called the cytoplasmic (or plasma) membrane, surrounded by a thick
layer of peptidoglycan (20-80 nm). The Gram-negative bacteria have only a thin layer of
peptidoglycan (1-3 nm) but on the outside of this there is a further outer membrane which acts
as an additional barrier.
The procedure for the Gram stain is as follows. Fixed cells are stained with a dark stain such
as crystal violet, followed by iodine which complexes with the stain in the cell wall of the
bacteria. Alcohol is added, which washes the dark stain of crystal violet-iodine out of ceils that
have thin cell walls but not from those that have thick cell walls. Finally, a paler stain such as
carbol fuschin, called a counter stain, is added which stains the decolorized cells pink but is not
seen on the dark staining cells that retained the first stain. The cells that retain the stain (with
thick cell walls) are called Gram-positive and appear dark purple under light microscopy. The
ones that lose the stain (with thin cell walls and an outer membrane) are called Gram-negative
and stain pink or pale purple
The Cell Wall
1.
The cell wall surrounds the plasma membrane and protects the cell from changes in
osmotic pressure（渗透压）and provides rigidity and strength.
2.
The bacterial cell wall consists of peptidoglycan（肽聚糖）, a polymer consisting of NAG
and NAM and short chains of amino acids.
3.
Gram-positive（革兰氏阳性） cell walls consist of many layers of peptidoglycan and also
contain teichoic acids（垣酸）.
4.
Gram-negative
（
革
兰
氏
阴
性
）
bacteria
have
a
lipidprotein-lipopolysaccharide-phospholipid outer membrane surrounding a thin
peptidoglycan layer.
5.
The outer membrane protects the cell from phagocytosis and penicillin（ 青霉素）, lysozyme
（溶菌酶）, and other chemicals.
6.
Porins（孔蛋白）are proteins that permit small molecules to pass through the outer
membrane; specific channel proteins allow other molecules to move through the outer
membrane.
7.
The lipopolysaccharide（脂多糖，LPS） component of the outer membrane consists of
sugars that function as antigens and lipid A, which is an endotoxin（内毒素）.
teichoic acid:
Gram-positive cell walls also contain large amounts of another polymer, called teichoic acid,
made up of glycerol or ribitol joined by phosphate groups. D-Ala, glucose or sugars may be
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attached to the glycerol or ribitol and the polymers are attached either directly to the NAM in
the peptidoglycan or to lipids in the membrane (in this case they are called lipoteichoic acids).
The function of these molecules is unclear but they may have a role in maintaining the structure
of the cell wall and in the control of autolysis.
periplasmic space（周质空间）
The outer membrane of Gram-negative bacteria acts as an additional barrier protecting the
peptidoglycan from toxic compounds such as lysozyme which act on the cell wall. It
creates an aqueous space between the two membranes called the periplasmic space which
is thought to have a gel-like structure with a loose network of peptidoglycan running
through it. Estimates as to the width of the peptidoglycan vary from 1-71 nm but it has
proved to be difficult to obtain a real definitive value. The periplasmic space contains a
range of proteins associated with:
• transport of nutrients into the cell;
• enzymes that are involved in nutrient acquisition such as proteases;
• enzymes that defend the cell against toxic chemicals such as в-lactamases that destroy
penicillin.
outer membrane
The outer membrane of Gram-negative bacteria is made up of phospholipids
membrane,but it also contains some unique features
1.
Pores formed by proteins called porins such as OmpF and OmpC that allow the passive
diffusion of small molecules into the periplasmic space.
2.
An abundant small lipoprotein called Braun's lipoprotein that is covalentlybound to
the peptidoglycan and is embedded in the outer membrane by it s hydrophobic lipid,
therefore holding the peptidoglycan and outer membraneclose together.
3.
LPS molecules are found in the outer leaflet of the outer membrane projecting into the
surrounding medium.
Atypical（缺陷的） cell walls
1.
Mycoplasma（支原体） is a bacterial genus that naturally lacks cell walls.
2. Archaeobacteria have pseudomurein（假肽聚糖）; they lack peptidoglycan.
3. . L forms are mutant bacteria with defective cell walls.
Archaeobacterial cell walls
One of the distinctive features of archaebacteria is the nature of the lipids in the plasma
membrane which, unlike the ester-linked lipids of eubacteria and eukaryotes are ether-linked to
glycerol. They are also long chained and branched. Archaebacterial cell walls and envelopes
show great diversity and complexity in structure. They do not contain peptidoglycan although
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some do have a similar compound called pseudomurein which contains N-acetyl-alosaminuronic
acid in place of muramic acid. Another common type of cell wall is the S-layer, a
two-dimensional, paracrystalline, array of protein or glycoprotein on the cell surface. Others
have thick polysaccharide walls outside their plasma membrane.
DAMAGE TO THE CELL WALL
peptidoglycan used to be a target for antimicrobial agents that destroy prokaryotic cells
specifically, but do not harm eukaryotic cells; an example of this is the antibiotic penicillin
(Topic F7). Lysozyme, a natural antibacterial agent found in tears and natural secretions, breaks
down the linkage between NAM and NAG. Removal of the cell wall under conditions where the
osmolarity of the medium is the same as the inside of the cell (isotonic solution) results in the
formation of round protoplasts( 原 生 质 体 ) (Gram-positives) or spheroplasts( 球 形 体 )
(Gram-negatives) which survive as long as the isotonicity is maintained. These structures lyse,
however, if placed in a dilute medium, illustrating the importance of peptidoglycan to the cells'
survival.
1.
In the presence of lysozyme, gram-positive cell walls are destroyed and the remaining
cellular contents are referred to as a protoplast.
2.
In the presence of lysozyme, gram-negative cell walls are not completely destroyed and
the remaining cellular contents are referred to as a spheroplast.
3.
Protoplasts and spheroplasts are subject to osmotic lysis.
4.
Antibiotics such as penicillin interfere with cell wall synthesis.
PLASMA (CYTOPLASMIC) MEMBRANE
1
The plasma membrane encloses the cytoplasm and is a phospholipid bilayer with
protein (fluid mosaic).
2
most of bacteria lack of steriol（固醇）
3
The plasma membrane is selectively permeable.
4
Plasma membranes carry enzymes for metabolic reactions, such as nutrient
breakdown, energy production, and photosynthesis.
5
Mesosomes—irregular infoldings of the plasma membrane—are now considered
artifacts
6
.Plasma membranes can be destroyed by alcohols and polymyxin.
CYTOPLASM
1
Cytoplasm is the fluid component inside the plasma membrane.
2
The cytoplasm is mostly water, with inorganic and organic molecules, DNA,
ribosomes, and inclusions.
RIBOSOMES
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1
The cytoplasm of a procaryote contains numerous 70S ribosomes; ribosomes consist of
rRNA and protein.
2
Protein synthesis occurs at ribosomes; this can be inhibited by certain antibiotics.
INCLUSIONS
1
Inclusions（内含物） are reserve deposits found in procaryotic and eucaryotic cells.
2
Among the inclusions found in bacteria are metachromatic granules （ 异 染 粒 ）
(inorganic phosphate), polysaccharide granules (，多糖，usually glycogen or starch), lipid
inclusions（ 脂滴）,sulfur granules（硫粒）, carboxysomes (，羧酶体，ribulose 1,5-diphosphate
carboxylase), and gas vacuoles（气泡）.
NUCLEAR AREA
1. The nuclear area contains the DNA of the bacterial chromosome. Bacteria can also contain
plasmids, which are extrachromosomal DNA circles.
capsule or slime layer
1.
capsule（ 荚 膜 ） or slime（ 黏 液 层 ） layer is a gelatinous polysaccharide and/or
polypeptide covering.
2.
Capsules may protect pathogens from phagocytosis（吞噬）.
3.
Capsules provide adherence to surfaces, prevent desiccation, and may provide
nutrients.
FLAGELLA
1.
Flagella（鞭毛） are relatively long filamentous appendages consisting of a filament, hook,
and basal body.
2.
Procaryotic flagella rotate to push the cell.Motile（运动）.
3.
bacteria exhibit taxis（趋性）—positive taxis is movement toward an attractant and
negative taxis is movementaway from a repellent.
FIMBRIAE AND PILIF
1.
fimbriae（菌毛） and pili（性毛） are short, thin appendages.
2.
Fimbriae help cells adhere to surfaces.
3.
Pili join cells for the transfer of DNA from one cell to another.
ENDOSPORES（芽孢）
1.
Endospores are resting structures formed by some bacteria for survival during adverse
environmental conditions.
2.
The process of endospore formation is called sporulation; the return of an endospore to its
vegetative state iscalled germination.
Endospores are a method as survival, not one of reproduction. Certain bacteria will form a spore
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within their cell membrane (an endospore) that allows them to wait out deteriorating
environmental conditions. Certain disease causing bacteria (such as the one that causes the disease
Anthrax) can be virulent (capable of causing an infection) 1300 years after forming their
endospore!）
BACTERIAL DIVISION
1.
2.
The normal reproductive method of bacteria is binary fission, in which a single cell
divides into two identical cells.
Some bacteria reproduce by budding., aerial spore formation, or fragmentation.
binary fission（二分裂）
The method by which bacteria reproduce. The circular DNA molecule is replicated;
then the cell splits into two identical cells, each containing an exact copy of the
original cell's DNA.
Actinomyces
Actinomycetes(放线菌) are filamentous, gram-positive bacilli that form a branching
mycelium.
Cyanobacteria（蓝细菌）：
Blue-green bacteria;unicellular or filamentous chains of cells that carry out
photosynthesis.
Rickttsias , chlamydias and mycoplasmas
The rickttsias（立克次氏体） and chlamydias（衣原体） are gram-negative obligate intracellular parasites
that key metabolic enzymes.
The rickettsias are extremely small, pleomorphic rods or coccobacilli that cannot synthessiz their own ATP.
Most have a complex life-style that cyces between arthropod vectors and vertebrate hosts.
The rickettsias are ususlly transmitted by tickor tick feces.
The chlamydias are small, gram-negative, pleomorphic, intracellular parasites that have no
catabolic pathways. They exist in two forms: the elementary body, which is the form transmitted
between human hosts through direct contact and body secretions, and the reticulate body, which
multiplies intracellularly.
Chlamydia trachomatis（沙眼衣原体） is the agent of several STDs: NGU (nongonococcal
urethritis),pelvic inflammatory disease, and lymphogranuloma venereum. It also causes ocular
trachoma, a serious eye infection.
Chlamydia pneumoniae(肺炎衣原体) is the agent of respiratory infections in young adults and
asthmatics.
Chlamydia psittaci（鹦鹉热衣原体） is the agent of ornithosis, an influenza-like disease carried by
birds that has serious systemic complications if untreated. Antibiotic therapy is usually successful.
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Mycoplasmas（支原体） are tiny pleomorphic bacteria that lack a cell wall. Although most
species are parasitic, mycoplasmas can be cultured on complex artificial media. They are
considered membrane parasites because they bind tightly to epithelial linings of the respiratory
and urogenital tracts.
Mycoplasma pneumoniae(肺炎支原体) is the agent of primary atypical pneumonia (walking
pneumonia).
M. hominis(人型支原体) and M. urealyticum(脲支原体) are agents of sexually transmitted
infections of the reproductive tract and kidneys, and more recently, of fetal infections.
M. incognitos is a recently identified pathogen that causes systemic infection by
suppressing the immune system.
Chapter 2
Review question
1. Diagram each of the following flagellar arrangements:
(a) Lophotrichous
(b) Monotrichous
(c) Peritrichous
2. Endospore formation is called ________ It is initiated
by __ . Formation of a new cell from an endospore is called
. .This process is triggered by
3.Draw the bacterial shapes listed in a, b, and c. Show how d, e, and f are special conditions
of a, b, and c, respectively.
(a) Spiral
(d) Spirochete
(b) Bacillus
(e) Streptobacilli
(c) Coccus
(f) Staphylococci
4. List three differences between procaryotic and eucaryotic cells.
5.Match the structures to their functions.
Cell wall
Endospore
Fimbriae
Flagella
caupsle
Plasma membrane
Ribosome
6. Of
(a)
(b)
(c)
(d)
(e)
(f)
A:Protection from osmotic lysis
B: Attachment
C: Protection from phagocytes
D: Resting
E: Protein synthesis
F: Selectively permeable
I: Transfer of genetic material
what value is each of the following to the cell?
Metachromatic granules
Polysaccharide granules
Lipid inclusions
Sulfur granules
Carboxysomes
Gas vacuoles
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7. Why is an endospore called a resting structure? Of what advantage is an endospore to a
bacterial cell?
8. Compare and contrast the following:
Protoplasts and spheroplasts
penicillin and lyzosome
Flagella and fimbriae
rickttsiae and chlamydias
9.Answer the following questions using the diagrams below, which represent cross sections
of bacterial cell walls.
(a) Which diagram represents a gram-positive bacterium? How can you tell?
(b) Explain how the Gram stain works to distinguish between these two types of cell
walls.
(c) Why does penicillin have no effect on most gram negative cells?
(d) How do essential molecules enter cells through each wall?
Lipopolysaccharide
Teichoic acid
Peptidoglycan
Phospholipid
Lipoprotein
Peptidoglycan Cell
Cell membrane
membrane
10.Why can procaryotic cells be smaller than eucaryotic cells and still carry on all the
functions for life?
11.Two types of procaryotic cells have been distinguished: eubacterial and archaeobacterial. How
do these cells differ from each other? How are they similar?
12.
What is the evolutionary advantage of the monolayer often found in Archaeal membranes?
13. Bacillus subtilis is a common soil bacterium. What genus does B. subtilis belong to?
14. Although prokaryotes and eukaryotes are distinguished by nuclear structure, other important
differences exist between these two cell types. Prokaryotes are smaller in size than eukaryotes, and
eukaryotes contain a membrane-enclosed nucleus and organelles within which many important
functions are carried out. The small size of prokaryotic cells affects their physiology, growth rate,
and ecology.
●List three morphological types of prokaryotes.
●What is a flagellum, and what does it do?
12
●What physical property of cells increases as cells become smaller?
15. The cell walls of Bacteria contain a polysaccharide called peptidoglycan. This material
consists of strands of alternating repeats of N-acetylglucosamine and N-acetylmuramic acid, with
the latter cross-linked between strands by short peptides. Archaea lack peptidoglycan but contain
walls made of other polysaccharides or of protein. The enzyme lysozyme destroys peptidoglycan,
leading to cell lysis.
●List the monomeric components of peptidoglycan.
●Why is peptidoglycan such a strong macromolecule?
●How does psuedopeptidoglycan resemble peptidoglycan? How do the two molecules differ?
●How is a protoplast generated?
16.In addition to peptidoglycan, Gram-negative Bacteria contain an outer membrane consisting of
lipopolysacchaaride, a protein, and lipoprotein. Proteins called porins allow for permeability
across the outer membrane, and a space called the periplasm is present, which contains various
proteins involved in important cellular functions.
●What components constitute the LPS layer of Gram-negative Bacteria?
●What is the function of porins, and where are they located in a Gram-negative cell wall?
●Why does alcohol readily decolorize Gram-negative bacteria?
17. The endospore is a highly resistant differentiated bacterial cell produced by certain types of
Gram-positive Bacteria. Spore formation leads to a nearly dehydrated spore core that contains
essential macromolecules and a variety of substances, such as calcium dipicolinate and small
acid-soluble proteins, absent from vegetative cells. Spores can remain dormant indefinitely but
germinate quickly when the appropriate trigger is applied.
●What is dipicolinic acid, and where is it found?
●What are SASPs, and what are their functions?
●What happens when an endospore germinates?
chapter 3 eukaryotic microorganisms
第 3 章 真核微生物
13
Eukaryote cell
A type of cell found in many organisms including single-celled protozoom and multicellular fungi,
plants, and animals; characterized by a membrane-bounded nucleus and other membraneous
organelles
eukaryotic cells construct
Appendages (cilia, flagella), glycocalyx, cell wall, cytoplasmic (or cell) membrane, ribosomes,
organelles(nucleus, nucleolus, endoplasmic reticulum, Golgi apparatus, mitochondria, chloroplasts,
cytoskeleton, microfilaments.
Main characterstic of eukarytic cells
1. The nucleus, which contains DNA in the form of chromosomes, is the most characteristic
eukaryotic organelle.
2. The nuclear membrane is connected to a system of parallel membranes in the cytoplasm,
called the endoplasmic reticulum.
3. The endoplasmic reticulum provides a surface for chemical reactions, serves as a
transporting network, and stores synthesized molecules.
4. 805 ribosomes are found in the cytoplasm or attached to the endoplasmic reticulum.
5. The Golgi complex consists of cisternae. It functions in secretion, carbohydrate synthesis,
and glycoprotein for mation.
6. Mitochondria are the primary sites of ATP production.They contain small 70S ribosomes
and DNA, and they multiply by fission.
7. Chloroplasts contain chlorophyll and enzymes for photosynthesis. Like mitochondria, they
contain 70S ribosomes and DNA and multiply by fission.
8. Lysosomes are formed from Golgi complexes. They store powerful digestive enzymes.
9. A pair of cylindrical structures called centrioles that are involved in cell division are near
the nucleus.
10.Both flagella and cilia contain a "nine pairs + two pairs"arrangement of microtubules.
Major Groups of eukaryotic microorganisms
eucaryotic microorganisms include the Fungi ,algae and protozoom..
Fungi
Fungi is composed of non-photosynthetic species Fungi include yeasts (unicellular budding cells)
and molds (filamentous cells called hyphae,菌丝) and some macroscopic fungi(mushrooms).
Major Groups of fungi: The four important divisions among the terrestrial fungi, given with
sexual spore type, are Zygomycota（接合菌纲） (zygospores，接合孢子), Ascomycota（子囊
菌纲） (ascospores，子囊孢子), Basidiomycota（担子菌纲） (basidiospores，担孢子), and
Deuteromycota（半知菌纲） (no sexual spores).
Yeast
1.
Yeasts are single cells that form buds（芽体） and sometimes short chains called
pseudohyphae（假菌丝）.
2.
Yeasts are 5~20μm in length and 1~5μm in diamater.
3.
The majority are harmless saprobes living off organic substrates such as glucose. A few are
14
parasites, living on the tissues of other organisms, but none are obligate.
4.
Yeast cell walls consist of glucan and mannan.
5. plasma membranes contain carbohydrate sattached to the proteins and sterols not found
in prokaryotic cells.
6. most of yeast cell have large vacuolars(液泡).budding is the main reproduction style of
yeast.In sexual reproduction, spores are formed through fusion of male and female strains and
the formation of a sexual called ascospore.Molds
hyphae are characteristic of the filamentous fungi called molds. some fungi
(mushrooms) produce multicellular structures such as fleshy fruiting bodies.
Importance of molds
Essential decomposers of plant and animal detritis in the environment with return of valuable
nutrients to the ecosystem. Economically beneficial as sources of antibiotics; used in making foods
and in genetic studies. Harmful plant pathogens; decompose fruits and vegetables; several fungi
cause infections, or mycoses; some produce substances that are toxic if eaten.
Hyphae of molds
Hyphae can also be classified according to their particular function. Vegetative hyphae(营养菌
丝) (mycelia) are responsible for the visible mass of growth that appears on the surface of a
substrate and penetrates it to digest and absorb nutrients. During the development of a fungal
colony, the vegetative hyphae give rise to structures called reproductive, or aerial hyphae（繁殖
菌丝）., which orient vertically from the vegetative mycelium. These hyphae are responsible for the
production of fungal reproductive bodies called spores.
Cell wall of molds
The main material of fungal cell walls is chitin.
Reproduction of molds
Primarily through spores formed on special reproductive hyphae .Their primary means of
reproduction involves asexual and sexual spores.
Asexual Spore
1. Sporangiospores（孢囊孢子） are formed by successive cleavages within a saclike head called a
sporangium,which is attached to a stalk, the sporangiophore. These spores are initially enclosed but
are released when the sporangium ruptures.
2. Conidia（分生孢子）(conidiospores) are free spores not enclosed by aspore-bearing sac. They
develop either by the pinching off of the tip of a special fertile hypha or by the segmentation of a
preexisting vegetative hypha. Conidia are the most common asexual spores
3. arthmspore (节孢子) A rectangular spore formed when a septate hypha fragments at the cross
walls.
4. chlamydospore（厚垣孢子） (klams-ih'-doh-spor) A spherical conidium formed by the thickening
of a hyphal cell. It is released when the surrounding hypha fractures, and it serves as a survival or
resting cell.
sexual spores
The majority of fungi produce sexual spores at some point. The nature of this process varies
15
from the simple fusion of fertile hyphae of two different strains to a complex union of differentiated
male and female structures and the development of special fruiting structures. Four different types of
sexual spores have been identified, but we will consider the three most common: zygospores（接
合孢子）, ascospores（子囊孢子）,oospore）卵孢子）， and basidiospores（担孢子）.
Zygospores* are sturdy diploid spores formed when hyphae of two opposite strains (called the
plus and minus strains) fuse and create a diploid zygote that swells and becomes covered by strong,
spiny walls. When its wall is disrupted, and moisture and nutrient conditions are suitable, the
zygospore germinates and forms a sporangium. Meiosis of diploid cells of the sporangium results in
haploid nuclei that develop into sporangiospores. Both the sporangia and the sporangiospores that
arise from sexual processes arc outwardly identical to the asexual type, but because the spores arose
dom the union of Iwo separate fungal parents, they are not genetically identical.
In general, haploid spores called ascospores are created inside a special fungal sac. or
ascus.Although details can vary among types of fungi, the ascus and ascospores are formed when two
different strains or sexes join together to produce offspring. In many species, the male sexual organ
fuses with the female sexual organ. The end result is a number of terminal cells, each containing a diploid
nucleus. Through differentiation, each of these cells enlarges to form an ascus, and its diploid nucleus
undergoes meiosis (often followed by mitosis) to form four to eight haploid nuclei that will mature
into ascospores. A rise ascus breaks open and releases the ascospores. Some species form an elaborate
fruiting body to hold the asci.
Basidiospores: are haploid sexual spores formed on the outside of a club-shaped cell called a
basidium)
Chapter 4 VIRUSES
第四章 病毒
A virus is a submicroscopic infectious particle composed of a protein coat and a nucleic acid
core. Viruses, like cells, carry genetic information encoded in their nucleic acid, and can undergo
mutations and reproduce; however, they cannot carry out metabolism, and thus are not considered
alive. Viruses are classified by the type of nucleic acid they contain, and the shape of their protein
capsule.
General Characteristics of Viruses
1. Depending on one's viewpoint, viruses may be regarded as exceptionally
aggregations of nonliving chemicals or as exceptionally simple living microbes.
complex
2. Viruses contain a single type of nucleic acid (DNA or RNA) and a protein coat, sometimes
enclosed by an envelope composed of lipids, proteins, and carbohydrates.
3. Viruses are obligatory intracellular parasites. They multiply by using the host cell's
synthesizing machinery tocause the synthesis of specialized elements that can transfer
the viral nucleic acid to other cells.
4. A virion is a complete, fully developed viral particle composed of nucleic acid
surrounded by a coat.
HOST RANGE
1. Host range refers to the spectrum of host cells in which a virus can multiply.
16
2. Depending on its host range, a virus is generally classified as an animal virus, bacterial
virus (bacteriophage), or plant virus. A virus can infect only certain species within each
class.
3. Host range is determined by the specific attachment site on the host cell's surface and the
availability of host cellular factors.
SIZE
1. Viral size is determined by filtration through membrane filters, ultracentrifugation, and
electron microscopy.
2. Viruses range from 20 to 300nm in diameter.
Viral Structure
NUCLEIC ACID
1. The proportion of nucleic acid in relation to protein in viruses ranges from about 1% to
about 50%.
2. Viruses contain either DNA or RNA, never both, and the nucleic acid may be single- or
double-stranded, linear or circular, or divided into several separate molecules.
CAPSID AND ENVELOPE
1. The protein coat surrounding the nucleic acid of a virus is called the capsid（衣壳）.
2. The capsid is composed of subunits, the capsomeres（衣壳粒）,which can be a single
type of protein or several types.
3. The capsid of some viruses is enclosed by an envelope consisting of lipids, proteins, and
carbohydrates.
4. Some envelopes are covered with carbohydrate-protein complexes called spikes（刺突）.
5. Viruses without envelopes are called naked viruses.
GENERAL MORPHOLOGY
1. Helical （螺旋对称）viruses (for example, tobacco mosaic virus) resemble long rods, and
their capsids are hollow cylinders surrounding the nucleic acid.
2. Polyhedral（多面体） viruses (for example, adenovirus，腺病毒) are many sided. Usually
the capsid is an icosahedron（二十面体）. Enveloped viruses are covered by an envelope
and are roughly spherical but highly pleomorphic（多型性的）. There are also enveloped
helical viruses (for example, influenza virus) and enveloped polyhedral viruses (for example,
herpes simplex virus).
3. Complex viruses have complex structures. For example, many bacteriophages have a
polyhedral capsid with a helical tail attached.
Taxonomy of Viruses
1. Classification of viruses is based on type of nucleic acid, morphological class, size of capsid,
and number of capsomeres.
2. Other classification schemes take into account the virus's susceptibility to microbial control
agents, immunological properties, site of multiplication, and method of transmission.
Isolation, Cultivation, and Identification of Viruses
1.
Viruses must be grown in living cells.
17
2.
The easiest viruses to grow are bacteriophages.
GROWTH OF BACTERIOPHAGES IN THE LABORATORY
The plaque method：
1. Mixes bacteriophages with host bacteria and nutrient agar.
2.
After several viral multiplication cycles, the bacteria in the area surrounding the original
virus are destroyed; the area of lysis is called a plaque.
3.
Each plaque can originate with a single viral particle or with more than one; the concentration
of viruses is given as plaque-forming units.
GROWTH OF ANIMAL VIRUSES IN THE LABORATORY
1. Cultivation of some animal viruses requires whole animals.
2. Some animal viruses can be cultivated in embryonated eggs.
3. Cell cultures are cells growing in culture media in the laboratory.
4. Viral growth can cause cytopathic effects in the cell culture.
VIRAL IDENTIFICATION
1. Serological tests are used most often to identify viruses. Viruses may be identified by
restriction enzyme fragments and nucleic acid base sequencing.
2.
Viral Multiplication
1. Viruses do not contain enzymes for energy production or protein synthesis.
2. For a virus to multiply, it must invade a host cell and direct the host's metabolic
machinery to produce viral enzymes and components.
MULTIPLICATION OF BACTERIOPHAGES
T-Even Bacteriophages
1. The T-even bacteriophages that infect E coli have been studied extensively.
2. In attachment, sites on the phage's tail fibers attach to complementary receptor sites on the
bacterial cell.
3. In penetration, phage lysozyme opens a portion of the bacterial cell wall, the tail sheath
contracts to force the tail core through the cell wall, and phage DNA enters the bacterial
cell. The capsid remains outside.
4. In biosynthesis, transcription of phage DNA produces mRNA coding for proteins necessary
for phage multiplication. Phage DNA is replicated, and capsid proteins are produced. During
the eclipse period, separate phage DNA and protein can be found.
5. During maturation, phage DNA and capsids are assembled into complete viruses.
6. During release, phage lysozyme breaks down the bacterial cell wall, and the multiplied
phages are released.
7. The time from phage adsorption to release is called burst time (20 to 40 minutes). Burst size,
the number of newly synthesized phages produced from a single infected cell, ranges from 50
to 200.
Lysogeny
1. During a lytic cycle, a phage causes the lysis and death of a host cell.
2. Some viruses can either cause lysis or have their DNA incorporated as a prophage into
the DNA of the host cell. The latter situation is called lysogeny.
18
3. Prophage genes are regulated by a represser coded for by the prophage. The prophage is
replicated each time the cell divides.
4. Exposure to certain mutagens can lead to excision of the prophage and initiation of the lytic
cycle.
5. Because of lysogeny, lysogenic cells become immune to reinfection with the same phage,
and the host cell can exhibit new properties.
6. A lysogenic phage can transfer bacterial genes from one cell to another through transduction.
Any genes can be transferred in generalized transduction, and specific genes can be
transferred in specialized transduction.
MULTIPLICATION OF ANIMAL VIRUSES
Animal viruses attach to the plasma membrane of the host cell.
1. Penetration of enveloped viruses occurs by endocytosis.
2. Animal viruses are uncoated by viral or host cell enzymes. The DNA of most DNA
viruses is released into the nucleus of the host cell. Transcription of viral DNA and
translation produce viral DNA and, later, capsid protein. Capsid protein is synthesized in
the cytoplasm of the host cell.
3. Retroviruses carry reverse transcriptase (RNA-dependent DNA polymerase), which
transcribes DNA from RNA.
4. After maturation, viruses are released. One method of release (and envelope formation)
is budding. Naked viruses are released through ruptures in the host cell membrane.
Effects of Animal Viral Infection on Host Cells
1. Cytopathic effects (CPE) are abnormalities that lead to damage or death of a host cell.
2. Cytopathic effects include inclusion bodies, polykaryocytes, and altered function.
Interferon
Interferon is produced by virus-infected cells and protects neighboring cells from viral
infection.
Viruses and Diseases
Viruses cause a variety of diseases among all groups of living organisms. Viral diseases
include the flu, common cold, herpes, measles, chicken pox, small pox, and encephalitis.
Antibiotics are not effective against viruses. Vaccination offers protection for uninfected
individuals.
Emergent Viruses
Viruses are usually quite specific as to their hosts and even to the types of cells they infect in
a multicellular host. Recently some viruses appear to have shifted their host: HIV, hantavirus, and
ebola appear to be either viruses shifting to a new (human) host or else viruses whose existence
and effects are just now being realized by scientists and the general public.
Viruses and Cancer
1. An excess of tissue due to unusually rapid cell multiplication is called a tumor. Tumors are malignant
19
(cancerous) or benign (noncancerous). Metastasis refers to the spread of cancer to other parts of the
body.
2. Tumors are usually named by attachment of the suffixoma to the name of the tissue from which the
tumor arises.
3. The earliest relationship between cancer and viruses was demonstrated in the early 1900s, when chicken
leukemia and chicken sarcoma were transferred to healthy animals by cell-free filtrates.
TRANSFORMATION OF NORMAL CELLS INTO TUMOR CELLS
1. Eucaryotic cells have proto-oncogenes that code for proteins necessary for the cells' normal growth. When
activated to oncogenes, these genes transform normal cells into cancerous cells.
2. Viruses capable of producing tumors are called oncogenic viruses.
3. Several DNA viruses and retroviruses are oncogenic.
4. The genetic material of oncogenic viruses becomes integrated into the host cell's DNA.Transformed cells
lose contact inhibition, contain virusspecific antigens (TSTA and T antigen), exhibit chromosomal
abnormalities, and can produce tumors when injected into susceptible animals.
ACTIVATION OF ONCOGENES
A single mutation can result in the production of a protein required for transformation.
1. Transduction of oncogenes could result in oncogene products being made in abnormal amounts or
at the wrong time.
2. Translocation of oncogenes could remove normal controls.
3. Gene amplification causes unusually large amounts of oncogene products.
DNA-CONTAINING ONCOGENIC VIRUSES
1. Oncogenic viruses are found among adenoviruses, hepesviruses, poxviruses, and papovaviruses.
2. The EB virus, a herpesvirus, causes infectious mononu cleosis and has been implicated in Burkitt's
lymphoma
and nasopharyngeal carcinoma. One type of herpes simplex virus (HHV 2), associated with over 90% of
genital
herpes infections, might be implicated in cervical cancer.
RNA-CONTAINING ONCOGENIC VIRUSES
1. Among the RNA viruses, only retroviruses seem to be oncogenic.
2. HTLV 1 and HTLV 2 have been associated with human leukemia and lymphoma.
3. The virus's ability to produce tumors is related to the production of reverse transcriptase. The DNA
synthe sized from the viral RNA becomes incorporated as a provirus into the host cell's DNA.
Plant Viruses
Plant viruses must enter plant hosts through wounds or with invasive parasites, such as
insects.
Viroids and Prions
Viroids are common plant pathogens which are a serious economic problem.
The RNA genomes of viroids are 246-375 nucleotides in length and share many
similarities:

They are all single stranded covalent circles
20




There is extensive intramolecular base pairing
A DNA-directed RNA polymerase makes both plus and minus strands
Replication does not depend on the presence of a helper virus
No proteins are encoded
Virusoids and Satellites
Virusoids or satellite RNAs are also several hundred nucleotides long circular and single stranded.
They depend on a helper virus for replication.
Chapter 4 virus
review questions
1. Viruses were first detected because they are filterable. What do we mean by the term
filterable, and how could this property have helped their detection before invention of the
electron microscope?
2. Why do we classify viruses as obligatory intracellular parasites?
3. List the four properties that define a virus. What is a virion?
4. Describe the three morphological classes of viruses, then diagram and give an example of
each.
5. Describe how bacteriophages are detected and enumerated by the plaque method.
6. Describe the multiplication of a T-even bacteriophage. Be sure to include the essential features
of attachment, penetration, biosynthesis, maturation, and release.
7. Recall from Chapter 1 that Koch's postulates are used todetermine the etiology of a disease. Why
is it difficult to determine the etiology of a viral infection such as influenza?
8. Assume that this strand of RNA is the nucleic acid for an RNA-containing animal virus:
UAGUCAAGGU.
(a) Describe the steps of RNA replication for a virus that contains a + strand of RNA.
(b) Describe the steps of RNA replication for a virus that contains a - strand of RNA.
(c) Describe the steps of RNA replication for a virus that contains double-stranded RNA.
(d) Describe the steps of RNA replication for a virus that contains reverse transcriptase.
9. In some viruses, capsomeres function as enzymes as well as structural supports. Of what
advantage is this to the virus.
10. Prophages and proviruses have been described as being similar to bacterial plasmids. What
similar properties do they exhibit? How are they different?
Chapter5 nurtution of microbes
第 5 章 微生物的营养
21
CHEMICAL REQUIREMENTS
1. Microorganisms require a carbon source; chemoheterotrophs use an organic molecule,
and autotrophs typcally use carbon dioxide.
2. Nitrogen is needed for protein and nucleic acid synthesis. Nitrogen can be obtained from
decomposition of proteins or from NH4+ or NO3-; a few bacteria are able to fix N2.
3. Water is also necessary to the growth of all microorganisms.
4. Other chemicals required for microbial growth include iroganic salt(sulfur, phosphorus, and
some trace elements), and, for some microorganisms, organic growth factors.
MOVEMENT OF MATERIALS ACROSS MEMBRANES
1. 1Movement across the membrane may be by passive processes, in which materials move
from higher to lower concentration and no energy is expended by the cell.
2. In simple diffusion, molecules and ions move until equilibrium is reached.
3. In facilitated diffusion, substances are transported by permeases across membranes from
high to low concentration.
4. Osmosis is the movement of water from high to low concentration across a selectively
semipermeable membrane until equilibrium is reached.
5. In active transport, materials move from low to high concentrations by permeases, and
the cell must expend energy.
6. In group translocation, energy is expended to modify chemicals and transport them
across the membrane.
Culture Media
1. A culture medium is any material prepared for the growth of bacteria in a laboratory.
2. Microbes that grow and multiply in or on a culture medium are known as a culture.
3. Agar is a common solidifying agent for a culture medium.
CHEMICALLY DEFINED MEDIA
A chemically defined medium is one in which the exact chemical composition is known.
COMPLEX MEDIA
1. A complex medium is one in which the exact chemical composition is not known.
ANAEROBIC GROWTH MEDIA AND METHODS
1. Reducing media chemically remove molecular oxygen
2. Petri plates can be incubated in an anaerobic jar or anaerobic glove box.
SPECIAL CULTURE TECHNIQUES
1. Some parasitic and fastidious bacteria must be cultured in living animals or in cell
cultures.
1. CO2 incubators or candle jars are used to grow bacteria requiring an increased CO 2
concentration.
SELECTIVE AND DIFFERENTIAL MEDIA
22
1. By inhibiting unwanted organisms with salts, dyes, orother chemicals, selective
media allow growth of only the desired microbe.
2.
Differential media are used to distinguish between different organisms.
ENRICHMENT CULTURE
An enrichment culture is used to encourage the growth of a particular microorganism in a
mixed culture.
Trace Elements
Microbes require very small amounts of other mineral elements, such as iron, copper,
molybdenum, and zinc; these are referred to as trace elements. Most are essential for
activity of certain enzymes, usually as co-factors. Although these components are
sometimes added to a laboratory medium, they are usually assumed to be naturally
present in tap water and other components of media. Even most distilled waters contain
adequate amounts, but tap water is sometimes specified to ensure that these trace
minerals will be present in culture media.
●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?
GLOSSARY
（常用微生物学专业名词词汇表）
active immunity（主动免疫）: Immunity acquired through direct stimulation of the immune
system by antigen.
active transport（主动运输）:Transport of molecules against a concentration gradient (from
regions of low concentration to regions of high concentration) with the aid of proteins in the cell
membrane and energy from ATP.
Alcohol fermentation（乙醇发酵）：is the formation of alcohol from sugar. Yeast, when under
anaerobic conditions, convert glucose to pyruvic acid via the glycolysis pathways, then go one
step farther, converting pyruvic acid into ethanol, a C-2 compound.
aerobe（好氧微生物）: A microorganism that lives and grows in the presence of free gaseous
oxygen (O2).
aflatoxin（黄曲霉毒素）: From Aspergillus flavus t, a mycotoxin that typically poisons moldy
animal feed and can cause liver cancer in humans and other animals.
AIDS（爱滋病）: Acquired Immune deficiency syndrome. The complex of signs and symptoms
characteristic of the late phase of human immunodeficiency virus (HIV) infection.
23
Ames test（艾姆氏实验）: A method for detecting mutagenic and potentially carcinogenic agents
based upon the genetic alteration of nutritionally defective bacteria
anabolism （ 合 成 代 谢 ） : The energy consuming process of incorporating nutrients into
protoplasm through biosynthesis.
anaerobe（厌氧微生物）: A microorganism that grows best, or exclusively, in the absence of
oxygen.
antibiotic（抗生素）:A chemical substance from one microorganism that can inhibit or kill another
microbe even in minute amounts.
antibody（抗体）: A large protein molecule evoked in response to an antigen that interacts
specifically with that antigen.
antigen（抗原）: Any cell, particle, or chemical that induces a specific immune response by B cells
or T cells and can stimulate resistance to an infection or a toxin.
antigenic determinant（抗原决定基）:The precise molecular group of an antigen that defines its
specificity and triggers the immune response.
antimetabolite（抗代谢物）:A substance such as a drug that competes with, substitutes for, or
interferes with a normal metabolite.
antiseptic（防腐剂）
：A growth-inhibiting agent used on tissues to prevent infection.
antiserum（抗血清）
：Antibody-rich serum derived from the blood of animals (deliberately
immunized against infectious or toxic antigen) or from people who have recovered from specific
nfections.
antitoxin（抗毒素）
：Globulin fraction of serum that neutralizesa specific toxin. Also refers to the
specific antitoxin antibody itself.
arthrospore（节孢子）
：A fungal spore formed by the septation fragmentation of hyphae.
ascospore（子囊）
：A spore formed within a saclike cell (ascus) of Ascomycota following nuclear
fusion and meiosis.
asepsis（无菌）
：A condition free of viable pathogenic microorganisms.
autoantibody（自身抗体）
：An "anti-self antibody having an ffinity for tissue antigens of the
subject in which it is formed.
autoantigen（自身抗原）
： Molecules that are inherently part of self but are perceived by the
immune system as foreign
24
autoimmune disease（自身免疫疾病）：The pathologic condition arising from the production of
antibodies against autoantigens. Example: rheumatoid arthritis. Also called autoimmunity
bacteriophage（噬菌体）
：A virus that specifically infects bacteria.
bacteriostatic（抑菌）
：Any process or agent that inhibits bacterial growth.
binary fission（二分裂）
：The formation of two new cells of approximately equal size as the result
of parent cell division.
B lymphocyte (B cell)： A white blood cell that gives rise to plasma cells and antibodies.
broad spectrum（广谱）
： A word to denote drugs that affect many different types of bacteria,
both gram-positive and gram-negative.
Capsid（衣壳）
：The protein covering of a virus's nucleic acid core. Capsids exhibit symmetry due
to the regular arrangement of subunits called capsomers.
capsomer（衣壳粒）
： A subunit of the virus capsid shaped as a triangle or disc.
capsule（荚膜）： In bacteria, the loose, gel-like covering or slime made chiefly of simple
polysaccharides. This layer is protective and can be associated with virulence.
Catabolism（分解代谢）
：The chemical breakdown of complex compounds into simpler units to be
used in cell metabolism.
cell-mediated immune（细胞介导免疫）： The type of immune responses brought about by T
cells, such as cytotoxic, suppressor, and helper effects.
chemoautotroph（化能自养菌）
：An organism that relies upon inorganic chemicals for its energy
and carbon dioxide for its carbon. Also called a chemolithotraph
chemotaxis（趋化性）
： The tendency of organisms to move in response to a chemical gradient
(toward an attractant or to avoid adverse stimuli).
Chemotherapy（化学治疗剂）
：The use of chemical substances or drugs to treat or prevent
disease.
Chitin（几丁质）
：A polysaccharide similar to cellulose in chemical structure. This polymer makes
up the homy substance of the exoskeletons of arthropods and certain fungi
complement（补体）
：In immunology, serum protein components hat act in a definite sequence
when set in motion either by an antigen-antibody complex or by factors of the alternative
(properdin) pathway.
Conldia（分生孢子）
：Asexual fungal spores shed as free units from the tips of fertile hyphae.
25
Conjugation（接合）：In bacteria, the contact between donor and recipient cells associated with
the transfer of genetic material such as plasmids. Can involvespecial (sex) pili. Also a form of
sexual recombination in ciliated protozoans.
Colony(菌落)： A macroscopic cluster of cells appearing on a solid medium, each arising from
the multiplication of a single cell.
Contaminant（污染物）
：An impurity; any undesirable material or organism.
Culture（培养物）
：The visible accumulation of microorganisms in or on a nutrient medium. Also,
the propagation of microorganisms with various media. curd
differential medium（鉴别培养基）
： A single substrate that discriminates between groups of
microorganisms on the basis of differences in their appearance due to different chemical reactions.
differential stain（鉴别染色）： A technique that utilizes two dyes to distinguish between
different microbial groups or cell parts by color reaction.
Disinfection（消毒）
：The destruction of pathogenic nonsporulating microbes or their toxins,
usually on inanimate surfaces.
ELISA（酶联免疫）
： Abbreviation for enzyme-linked immunosorbent assay, a very sensitive
serological test used to detect antibodies in diseases such as AIDS。
endospore（芽孢）
： A small, dormant, resistant derivative of a bacterial cell that germinates under
favorable growth conditions into a vegetative cell. The bacterial genera Bacillus and Clostridiim
are typical sporeformers.
endotoxin（内毒素）
： A bacterial intracellular toxin that is not ordinarily released (as is exotoxin).
Endotoxin is composed of a phospholipid-polysaccharide complex that is an integral part of
gram-negative bacterial cell walls. Endotoxins can cause severe shock and fever.
enriched medium（加富培养基）
： A nutrient medium supplemented with blood, serum, or some
growth factor to promote the multiplication of fastidiousmicroorganisms.
enveloped virus（包膜病毒）
：A virus whose nucleocapsid is enclosed by a membrane derived in
part from the host cell. It usually contains exposed glycoprotein spikes specific for the virus.
essential nutrient
（必须营养）
：Any ingredient such as a certain amino acid, fatty acid, vitamin, or
mineral that cannot be formed by an organism and must be supplied in the diet. A growth factor.
eucaryotic cell（真核细胞）： A cell that differs from a procaryotic cell chiefly by having a
nuclear membrane (a well-defined nucleus), membrane-bound subcellular organdies, and mitotic
26
cell division.
Exotoxin（外毒素）
：A toxin (usually protein) that is secreted and acts upon a specific cellular
target. Examples: botulin, tetanospasmin, diphtheria toxin, and erythrogenic toxin.
Facultative（兼性的）
：Pertaining to the capacity of microbes to adapt or adjust to variations; not
obligate. Example: The presence of oxygen is not obligatory for a facultative anaerobe to grow.
Fermentation（发酵）
：The extraction of energy through anaerobic degradation of substrates into
simpler, reduced metabolites. In large industrial processes, fermentation can mean any use of
microbial metabolism to manufacture organic chemicals or other products.
Flagellum（鞭毛） -- Hair-like structure attached to a cell, used for locomotion in many protists
and prokaryotes. The prokaryotic flagellum differs from the eukaryotic flagellum in that the
prokaryotic flagellum is a solid unit composed primarily of the protein flagellin, while the
eukaryotic flagellum is composed of several protein strands bound by a membrane, and does not
contain flagellin. The eukaryotic flagellum is sometimes referred to as an undulipodium.
Genotype（表型）
：The genotype is ultimately responsible for an organism's phototype, or expressed
characteristics.
Glycolysis（糖酵解）
：The energy-yielding breakdown (fermentation) of glucose to pyruvic or lactic
acid. It is often called anaerobic glycolysis because no molecular oxygen is consumed in the
degradation.
Gram stain（革兰氏染色）
：A differential stain for bacteria useful in identification and taxonomy.
Gram-positive organisms appear purple from crystal violet-mordant retention; whereas gram-negative
organisms appear red after loss of crystal violet and absorbance of the safranin counterstain.
Granulocyte（粒细胞）
：A mature leukocyte that contains noticeabte granules in a Wright stain.
Examples: neutrophils, eoainophils, and basophils.
growth factor（生长因子）
： An organic compound such as a vitamin or amino acid that must be
provided in the diet to facilitate growth. An essential nutrient.
Halophlle（嗜盐菌）
： A microbe whose growth is either stimulated by salt or requires a high
concentration of salt for growth.
H antigen（H-抗原）
： The flagellar antigen of motile bacteria. H comes from the German word
hauch that denotesthe appearance of speading growth on solid.
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helper T cell（辅助 T-细胞）：A class of thymus-atimulated lymphocytes that facilitate various
immune activities such as assisting B cells and macrophages. Also called a T helper cell.
Heterotroph（异养菌）
： An organism that relies upon organic compounds for its carbon and energy
needs.
Immunity（免疫）
：An acquired resistance to an infectious agent due to prior contact with that agent.
immunogen（免疫原）
： Any substance that induces a state of sensitivity or resistance after
processing by the immune system of the body.
immune system（免疫系统）
：One of the eleven major body organ systems in vertebrates; defends
the internal environment against invading microorganisms and viruses and provides defense
against the growth of cancer cells.
immunoglobulin（免疫球蛋白）
： The chemical class of proteins to which antibodies belong.
Inclusion（内含物）
： A relatively inert body in the cytoplasm such as storage granules, glycogen,
fat, or some other aggregated metabolic product.
Infection（感染）： The entry, establishment, and multiplication of pathogenic organisms within a
host.
infectious disease（感染性疾病）
： The state of damage or toxicity in the body caused by an
infectious agent.
Inflammation（发炎）
： A natural, nonspecific response to tissue injury that protects the host from
further damage. It stimulates immune reactivity and blocks the spread of an infectious agent.
Inoculation（接种）
： The implantation of microorganisms into or upon culture media.
Interferon（干扰素）： Naturally occurring polypeptides produced by fibroblasts and lymphocytes
that can block viral replication and regulate a variety of immune reactions.
Isolation（分离）
： The separation of microbial cells by serial dilution or mechanical dispersion on
solid media to achieve a clone or pure culture.
Latency（潜伏）
： The state of being inactive. Example: a latent virus or latent infection.
L form（L-型菌）
： L-phase variants; wall-less forms of some bacteria that are induced by drugs or
chemicals.
Lipopolysaccharide（脂多糖，LPS）： A molecular complex of lipid and carbohydrate found in
the bacterial cell wall. The lipopolysaccharide (LPS) of gram-negative bacteria is an endotoxin with
generalized pathologic effects such as fever
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Lysis（溶解）
： The physical rupture or deterioration of a cell.
Lysogeny（溶原性）
： The indefinite persistence of bacteriophage DNA in a host without bringing
about the production of virions. A lysogenic cell can revert to a lytic cycle, the process that ends in
lysis.
lysosome （溶酶体）
：A cytoplasmic organelle containing lysozyme and other hydrolytic enzymes.
lysozyme（溶菌酶）
： An enzyme that attacks the bonds on bacterial peptidoglycan. It is a natural
defense found in tears and saliva.
macrophage A while blood cell derived from a monocyte that leaves the circulation and enters
tissues. These cells are important in nonspecific
mixed culture（混合培养）
： A container growing two or more different, known species of
microbes.
monoclonal antibody（单克隆抗体）
： An antibody produced by a clone of lymphocytes that
respond to a particular antigenic determinant and generate identical antibodies only to that
determinant.
Monocyte（单核细胞）
： A large mononuclear leukocyte normally found in the lymph nodes,
spleen, bone marrow, and loose connective tissue. This type of cell makes up 3% to 7% of
circulating leukocytes.
Mutagen（诱变剂）：Any agent that induces genetic mutation. Examples: certain chemical
substances, ultraviolet，light, radioactivity.
Mutation（突变）
： A permanent inheritable alteration in the DNA sequence or content of a cell.
Mycelium（菌丝体）
： The filamentous mass that makes up a mold. Composed of hyphae.
narrow spectrum（窄谱）
： Denotes drugs that are selective and limited in their effects. For
example, they inhibit either gram-negative or gram-positive bacteria, but not both.
negative stain（负染色）：A staining technique that renders the background opaque or colored and
leaves the object unstained so that it is outlined as a colorless area
nitrogen fixation（固氮）
：A process occurring in certain bacteria in which atmospheric Na gas is
converted to a form (NH^ usable by plants.
Nucleocapsid（核衣壳）
： In viruses, the close physical combination of the nucleic acid with its
protective covering.
Nucleoid（拟核）
：The basophilic nuclear region or nuclear body that contains the bacterial
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chromosome.
Nutrient（营养物质）：Any chemical substance that must be provided to a cell for normal
metabolism and growth. Macronutrients are required in large amounts, and micronutrients in small
amounts.
Obligate（专性的）
： Without alternative; restricted to a particular characteristic. Example: An
obligate parasite survives and grows only in a host; an obligate aerobe must have oxygen to grow;
an obligate anaerobe is destroyed by oxygen.
Parasite（寄生）
： An organism that lives on or within another organism (the host), from which it
obtains nutrients and enjoys protection. The parasite produces some degree of harm in the host
indirectly by donation of preformed immune substances (antibodies) produced in the body of
another Individual.
Pasteurization（巴斯德消毒）
： Heat treatment of perishable fluids such as milk, fruit juices, or
wine to destroy heat-sensitive vegetative cells, followed by rapid chilling to inhibit growth of
survivors and germination of spores. It prevents infection and spoilage.
Pathogen（病原体）
：Any agent, usually a virus, bacterium, fungus, protozoan, or helminth, that
causes disease.
Saprophytes(腐生型) Organisms that obtain their nutrients from decaying plants and animals.
Saprophytes are important in recycling organic material.
Pathogenidty（致病性）：The capacity of microbes to cause disease.
Pathology（病原学）
：The structural and physiological effects of disease on the body.
passive transport（被动扩散）Diffusion across a plasma membrane in which the cell expends no
energy.
Penicillins（青霉素）
：A large group of naturally occurring and synthetic antibiotics produced by
penicillium mold and active against the cell wall of bacteria.
Peptidoglycan(肽聚糖)： A network of polysaccharide chains cross-linked by short peptides that
forms the rigid part of bacterial cell walls. Gram-negative bacteria have a smaller amount of this
rigid structure than do gram-positive bacteria.
Plasmids（质粒）Self-replicating, circular DNA molecules found in bacterial cells; often used as
vectors in recombinant DNA technology. Small circles of double-stranded DNA found in some
bacteria. Plasmids can carry from four to 20 genes. Plasmids are a commonly used vector in
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recombinant DNA studies.
periplasmic space（周质空间）
：The region between the cell wall and cell membrane of the cell
envelopes of gram-negative bacteria.
Phage（噬菌体）
：A bacteriophage; a virus that specifically parasitizes bacteria.
Phenotype（表型）： The observable characteristics of an organism produced by the interaction
between its genetic potential (genotype) and the environment.
Photoautotroph（光能自养菌）
： An organism that utilizes light fails energy and carbon dioxide
chiefly for its' carbon needs.
Pilus（性丝） Projection from surface of a bacterial cell (F+) that can donate genetic material to
another (F-).
prokaryote cell（原核细胞）： A small, simple cell lacking a true nucleus, a nuclear envelope,
and membrane-enclosed organelles
prophage（前噬菌体）
：A lysogenized bacteriophage; a phage that is latently incorporated into the
host chromosome instead of undergoing, viral replication and lysis. prophylactic Any device,
method, or substance used to prevent disease.
Protoplast（原生质体）：A bacterial cell whose cell wall is completely kicking and that is
vulnerable to osmotic lysis.
Pseudohypha（假菌丝）
：A chain of easily separated, spherical to sausage-shaped yeast cells
partitioned by constrictions rather than by septa.
Psychrophile（嗜冷菌）
：A microorganism that thrives at low temperature (0°-20°C), with a
temperature optimum of 0°-15°C.
respiratory chain（呼吸链）：In cellular respiration, a series of electron-carrying molecules that
transfers energy-rich electrons and protons to molecular oxygen. In transit, energy is extracted and
conserved in the form of ATP.
reverse transcriptase（逆转录酶）
：The enzyme possessed by retroviruses that carries out the
reversion of RNA to DNA—a form of reverse transcription.
SCP（单细胞蛋白）
：Abbreviation for single-cell protein, a euphemistic expression for microbial
protein intended for human and animal consumption..
selective media（选择培养基）
： Nutrient media designed to favor the growth of certain microbes
and to inhibit.
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Serotyping（血清型）：The subdivision of a species or subspecies into an immunologic type, based
upon antigenic characteristics.
sexual reproduction（有性繁殖）A system of reproduction in which two haploid sex cells fuse to
produce a diploid zygote.
Spheroplast（球形体）
： A gram-negative cell whose peptidoglycan, when digested by lysozyme,
remains intact but is osmotically vulnerable
spike（刺突）
：A receptor on the surface of certain enveloped viruses that facilitates specific
attachment to the host cell.
Spirillum（螺菌）
：A type of bacterial cell with a rigid spiral shape and external flagella.
Spirochete（螺旋体）
：A coiled, spiral-shaped bacterium that has endoflagella and flexes as it
moves.
Sporangium（孢囊）：A fungal cell in which asexual spores are formed by multiple cell cleavage.
Sterilization（灭菌）
：Any process that completely removes or destroys all viable microorganisms,
including viruses, from an object or habitat. Material so treated is sterile.
Strain（菌株）
：In microbiology, a set of descendants cloned from a common ancestor that retain
the original characteristics. Any deviation from the original is a different strain.
subcellular vaccine（亚单位疫苗）
： A vaccine against isolated microbial antigens rather than
against the entire organism.
superoxide ion（超氧离子）
： A toxic radical form oxygen metabolism
suppressor T cell（抑制 T 细胞）
：A class of T cells that inhibits the actions of B cells and other T
cells.
temperate phage（温和噬菌体）
：A bacteriophage that enters into a less virulent state by becoming
incorporated into the host genome as a prophage instead of in the vegetative or lytic form that
eventually destroys the cell.
thermal death point（致死温度）
：The lowest temperature that achieves sterilization in a given
quantity of broth culture upon a 10-minute exposure. Examples:55°C for Escherichia coil. 60°C for
Mycobaaerium tuberculosis, and 120°C for spores.
thermal death time( 热致死时间)：The least time required to kill all cells of a culture at a specified
temperature.
Therrnophlle（嗜热菌）
：A microorganism that thrives at a temperature of 50°C or higher.
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T lymphocyte (T cell)：A white blood cell that is processed in the thymus gland and is involved in
cell-mediated immunity.
Toxoid（类毒素）
：A toxin that has been rendered nontoxic but is still capable of eliciting the
formation of protective antitoxin antibodies; used in vaccines.
Transduction（转导）
：The transfer of genetic material from one bacterium to another by means of
a bacteriophage vector.
Transformation（转化）：In microbial genetics, the transfer of genetic material contained in
"naked" DNA fragments from a donor cell to a competent recipient cell.
Transposon（转座）：A DNA segment with an insertion sequence at each end, enabling it to
migrate to another plasmid, to the bacterial chromosome, or to a bacteriophage.
Vaccine（免疫法）：Originally used in reference to inoculation with the cowpox or vaccinia virus
to protect against smallpox. In general, the term now pertains to injection of whole microbes (killed
or attenuated), toxoids, or parts of microbes as a prevention or cure for disease.
Virold（类病毒）
：An infectious agent that, unlike a virion, lacks a capsid and consists of a closed
circular RNA molecule. Although known viroids are all plant pathogens, it is conceivable that
animal versions exist.
Zygospore（接合孢子）
：A thick-walled sexual spore produced by the zygomycete fungi. It
develops from the union of two hyphae, each bearing nuclei of opposite mating types.
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