Biology of microorganisms

Microorganisms and Microbiology

Chapter 1


Chapter outline

1.1 What is a microbe?

1.2 The importance of Microbiology

1.3 Microbes in our lives

1.4 The history of microbiology

1.5 Important events in the development


of microbiology

Concepts

•
Microorganisms are responsible for many of the changes
observed in organic and inorganic matter (e.g., fermentation and
the carbon, nitrogen and sulfur cycles that occurred in nature.


•
The development of microbiology as a scientific discipline has
depended on the availability of the microscope and the ability to
isolate and grow pure cultures of microorganisms.


•
Microbiology is a large discipline, which has a great impact on
other areas of biology and general human welfare






The word microbe (microorganism) is used to
describe an organism that is so small that can
not be seen without the use of a microscope.
Viruses, bacteria, fungi, protozoa and some
algae are all included in this category.

1.1 What is a microbe?


Our world is populated by
invisible creatures too small to
be seen with the unaided eye.
These life forms, the microbes
or microorganisms, may be
seen only by magnifying their
image with a microscope.


Microbial world

Organisms

(living)

Infectious agents

(non
-
living)

Prokaryotes
(unicellular)

eukaryotes

viruses

viroids

prions

Eubacteria

Archaea

Algae
(unicellular
or
multicellular)

Fungi
(unicellular
or
multicellular)

Protozoa
(unicellular)

Other
(multicellular
organisms)

Most of the bacteria, protozoa, and fungi are
single
-
celled microorganisms, and even the
multicelled microbes do not have a great range
of cell types. Viruses are not even cells, just
genetic material surrounded by a protein coat
and incapable of independent existence.

The size and cell type of microbes



Microbe

Approximate range of
sizes


Cell type


Viruses


0.01
-
0.25
µm


Acellular


Bacteria


0.1
-
10
µm


Prokaryote


Fungi


2
µm
-
>
1m


Eukaryote


Protozoa


2
-
1000
µm


Eukaryote


Algae


1
µm
-
several meters


Eukaryote

The size and cell type of microbes

Microbes impinge on all aspects of life, just a few
of these are listed below:

The environment

Medicine

Food

Biotechnology

Research

1.2 The importance of microbiology

•
The environment

•
Medicine

•
Food

•
Biotechnology

•
Research

Press here to continue


Microbes are responsible for the geochemical
cycles. They are found in association with plants
in symbiotic relationships. Some microbes are
devastating plant pathogens, but others may act
as biological control agents against diseases.

The disease
-
causing ability of some microbes
is well known. However, microorganisms have
also provided us with the means of their control
in the form of antibiotics and other medically
important drugs.

Microbes have been used to produce food,
from brewing and wine making, through
cheese production and bread making, to the
manufacture of soy sauce. But microbes are
also responsible for food spoilage.

Traditionally microbes have been used to
synthesize important chemicals. The
advent of genetic engineering techniques
has led to the cloning of polypeptides into
microbes.

Microbes have been used as model organisms for
the investigation of biochemical and genetical
processes. Millions of copies of the same single
cell can be produced very quickly and give plenty
of homogeneous experimental material. Most
people have no ethical objections to experiments
with these microorganisms.

1.3 Microbes in our lives

•

Microorganisms

as

Disease

Agents

•

Microorganisms

and

Agriculture

•

Microorganisms

and

the

Food

Industry

•

Microorganisms,

Energy,

and

the

Environment

•

Microorganisms

and

the

Future


Branches of
Microbiology

Bacteriology

Protozoology

Parasitology

Microbial Morphology

Mycology

Virology

Phycology or Algology

Microbial physiology

Microbial taxonomy

Microbial genetics

Molecular biology

Microbial ecology

The future of microbiology is bright

Microbiology is one of the most rewarding of
professions, because it gives its practitioners the
opportunity to be in contact with all the other
natural science and thus to contribute in many
different ways to the betterment of human life.

1.4 The history of microbiology

In the field of observation, chance favors
only prepared minds.


------

Louis Pasteur


The discovery of microorganisms

The spontaneous generation conflict

The recognition of microbial role in
disease

The discovery of microbial effects on
organic and inorganic matter

The development of microbiology in
this century

The discovery of microorganisms

The first person to
accurately observe and
describe microorganisms

Antony van Leeuwenhock
(1632
-
1723)

The first person to observe and describe microorganisms
was the amateur microscopist Antony van leeuwenhoek
of Delft, Holland.

Leeuwenhock made his simple, single
-
lens
microscope which could amplify the object
being viewed 50
–

300 times. Between 1673
-
1723, he wrote a series of letters to the Royal
Society of London describing the microbes he
observed from the samples of rainwater, and
humam mouth.

Leeuwenhoek’s
drawings of
bacteria from the
human mouth
.

A drawing of one
of the microscopes
showing the lens a;
mounting pin b;
and focusing
screws c and d.

lens

Object
being
viewed

adjusting

screws

Pasteur’s contributions:

Louis Pasteur working in his
laboratory

Louis Pasteur (1822
–

1895)

•

Pasteur (1857) demonstrated
that lactic acid fermentation is
due to the activity of micro
-
organisms

•

Pasteur (1861) conflict over
spontaneous generation
–

birth
of microbiology as a science

•

Pasteur (1881) developed
anthrax vaccine

•

Pasteurization


Spontaneous generation

–

that living
organisms could develop from nonliving
or decomposing matter.

The spontaneous generation conflict

Pasteur’s swan neck flasks used in his experiments
on the spontaneous generation of microorganisms

Conclusion:

Microorganisms are not spontaneously
generated from inanimate matter, but
are produced by other microorganisms

Robert Koch in his laboratory

The recognition of microbial role in disease

Robert Koch (1843
–

1910)

Koch’s demonstration of special organisms
cause special diseases


Koch’s postulates

•
The microorganisms must be present in every
case of the disease but absent from healthy
organisms.

•
The suspected microorganisms must be isolated
and grown in a pure culture.

•
The disease must result when the isolated
microorganisms is inoculated into a healthy
host.

•
The same microorganisms must be isolated
again from the diseased host

The Golden age of microbiology

•

Koch and pure cultures

•

Fermentation and Pasteurization

•

Germ theory of disease

•

Vaccination

The discovery of microbial
effects on organic and
inorganic matter

•

The Russian microbiologist
Winograsky discovered that soil
bacteria could oxidize iron, sulfur
and ammonia to obtain energy,
and also isolated nitrogen
–
fixing
bacteria.

•

Beijerinck made fundamental
contributions to microbial ecology.
He isolated Azotobacter and
Rhizobium.

Alexander Fleming
(1881
-
1955
)

Sir Alexander Fleming
discovered the antibiotic
penicillin. He had the
insight to recognize the
significance of the
inhibition of bacterial
growth in the vicinity of
a fungal contaminant.

Date Microbiological History

1676 Leeuwenhoek discovers "animalcules"

1857

Pasteur shows that lactic acid fermentation is due to a


microorganism

1861

Pasteur shows that microorganisms do not arise by


spontaneous generation

1867 Lister publishes his work on antiseptic surgery

1869 Miescher discovers nucleic acids

1876
-
1877 Koch demonstrates that anthrax is caused by Bacillus


anthracis

1880

Laveran discovers Plasmodium, the cause of malaria

1881 Koch cultures bacteria on gelatin


Pasteur develops anthrax vaccine

1.5 Important events in the development
of microbiology

1884 Koch's postulates first published Metchnikoff describes


phagocytosis Gram stain developed

1887 Petri dish (plate) developed by Richard Petri

1889

Beijerinck isolates root nodule bacteria

1899

Beijerinck proves that a virus particle causes the tobacco


mosaic disease

1921 Fleming discovers lysozyme

1923 First edition of Bergey's Manual

1928 Griffith discovers bacterial transformation

1929 Fleming discovers penicillin

1933

Ruska develops first transmission electron microscope

1935 Stanley crystallizes the tobacco mosaic virus


1944

Avery shows that DNA carries information during


transformation Waksman discovers streptomycin


Watson and Crick propose the double helix structure


for DNA

1961
-
1966 Cohen et al use plasmid vectors to clone genes in


bacteria

1980 Development of the scanning tunneling microscope

1983
-
1984 The polymerase chain reaction developed by Mullis

1990 First human gene
-
therapy testing begun

1997

Discovery of Thiomargarita namibiensis, the largest


known bacterium Escherichia coli genome sequenced

2000

Discovery that Vibrio cholerae has two separate


chromosomes


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
.
Who

was

the

first

person

to

use

solid

culture

media

in

microbiology?

What

advantages

do

solid

media

offer

for

the

culture

of

microorganisms?

REVIEW QUESTIONS:


4
.
What

is

the

enrichment

culture

technique

and

why

was

it

a

useful

new

method

in

microbiology?


5
.
When

and

how

Alexander

Fleming

discovered

antibiotics?

1
.

Pasteur's

experiments

on

spontaneous

generation

were

of

enormous

importance

for

the

advance

of

microbiology,

having

an

impact

on

the

methodology

of

microbiology,

ideas

on

(he

origin

of

life,

and

the

preservation

of

food,to

name

just

a

few
.

Explain

briefly

how

the

impact

of

his

experiments

was

felt

on

each

of

the

topics

listed
.

APPLICATION QUESTIONS:


2. Describe the various lines of proof
Robert Koch used to definitively associate
the bacterium Mycobacterium tuberculosis
with the disease tuberculosis. How would
his proof have been flawed if any of the
tools he developed for studying bacterial
diseases had not been available for his
study of tuberculosis?


Ronald M.Atlas Clifford Renk Principles of Microbiology.

沈萍
†
1999⸠
微生物学

高等教育出版社。

J
。尼克林著

林雅兰等译。

科学出版社。

周德庆
†
2002⸠
微生物学教程
†
第二版。高等教育出版社。

李阜棣
†
胡正嘉

⸠2000
微生物学。

第五版。中国农业出版社

。

赵斌
†
何绍江
⸠′ 02
微生物学实验。科学出版社。

Johnson.case. Laboratory Experiments in Microbiology.

John P.Harley Lansing M.Prescott Microbiology 3th Edition.

Lansing, M. Prescott ;John, P. Harley; and Donald, A. Klein . 2002. Microbiology, 5th ed. McGraw
-
Hill .

Gerard J. Tortora ; Bardell R. Funke ; Christine L. 1998. Case. Microbiology An Introduction , 6th .
Benjamin/Cummings.

Michael, T. Madigan; John, M. Martinko; and Jack, Parker. 2003. Brock Biology of Microorganisms ,
10th . Prentice
-
Hall.


References: