Introduction to Microbiology

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Feb 12, 2013 (4 years and 2 months ago)

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Introduction to Microbiology



Microbiology

is the study of microorganisms, a large and diverse group
of microscopic organisms
which must be viewed with a micro
scope
that
exist as single cells or cell clusters; it also includes viruses, which are
microscop
ic but not cellular

.


Importance of microbiology



The importance of microbiology includes
: used in biomedical research,
creation of medicines, environmental applications and new research tools.



Bacteria are important for fixing N2 in a usable form
for plants.





Bacteria and some fungi are important in decomposition and recycling
of materials.



Industry applications of microbiology: waste management, food
industry, mining, medicine, research and biotechnology.

History of Microbiology


T
he history of microbiology can be summarized in the
following:



1660’s

Robert Hooke

observed microorganisms for the first time with
a microscope and coined the term “cell”.




1632
-
1723

Anton van Leeuwenhoek

having observed the first
bacteria.



1796

First scientific Small pox vaccination

by

Edward Jenner
.




1828
-
1898

Ferdinand Cohn

developed the first classification scheme
based on bacteria
l

shape.


Cohn detailed and descr
ibed the

life cycle of
Bacillus, and he put the first

c
lassification
s
ystem

of bacteria called
Cohn’s Classification System

divided into four groups
:



Sphaerobacteria are spherically shaped.



Microbacteria are rod shaped



Desmobacteria are filamentous



Spirobacteri
a are spiral shaped



1822
-
1895

Louis Pasteur

Defined pasteurization to prevent spoilage
of food by bacteria, develop Rabies vaccination and disproved the
scientific dogma of “Spontaneous Generation”.


He defined “Germ
Theory” and demonstrated that germs were responsible for

disease.




1843
-
1910

Robert Koch

identified anthrax and developed agar growth
medium.


Koch’s postulates was a systematic method to establish the
microbial cause of disease.



Ignaz Semmelweis

was the first to recognize the need for good
hygiene duri
ng medical procedures.


The first to identify nosocomial
infections

a
nd
a
dvocated washing hands to stop the spread of disease
.





1827
-
1912

Joseph Lister

developed antiseptic methods for use in
surgery and medicine.



1854
-
1915

Paul Ehrlich

developed c
hemotherapy to cure infectious
diseases and discovers antibiotics to treat sleeping sickness and syphilis

with the

d
eveloped
the
acid
-
fast
s
tain
.



Invented Petri Dish
by

R.J. Petri
.



Develop
ed Gram Stain

by
Christian Gram
.



Recognized viral dependence on cells for reproduction
by

Martinus
Beijerinck.




1881
-
1951

Alexander Fleming

discovered penicillin and lysozyme.





1864
-
1920

Dmitri Ivansvski

discovered the first virus which is known
as the tobacco mosaic virus (TMV).




1952

Hershey & Chase

Experiments identified that
DNA was the
genetic material of bacteriophages.





Hershey Case Experiment
: using phage radioactively labeled with
P32 (DNA) or S35 (protein) they infected bacteria cells.


They found the
P32 inside the bacteria not S35.




1977

Developed a method to seq
uence DNA
by

W. Gilbert & F.
Sanger.



1983

Polymerase Chain Reaction invented
by

Kary Mullis
.



1995

First microbial g
enomic sequence published
by
H. influenzae.



Anatomy of bacteria



The
bacterial cell is a
prokaryote cell

which
is simpler, and therefore
smaller, than a eukaryote cell, lacking a
nucl
eus
and most of the other
organelles
of eukaryotes. Nuclear material of prokaryotic cell consist of a
single chromosome which is in direct contact with cytoplasm. Here the
undefined nuclear region in the cytoplasm is called
nucleoid.

A prokaryotic cell ha
s three architectural regions:


On the outside
,
flagelig
and p
illi

project from the

cell’s surface. These
are structures (not present in all prokaryotes) made of proteins that
facilitate movement and communication between cells;


Enclosing the cell

is
the
cell envelope



generally consisting of a
cell
wall
covering a
plasma membrane

though some bacteria also have a
further covering layer called a
capsule
.
The envelope gives rigidity to the
cell and separates the interior of the cell from its environment
, serving as
a protective filter. Though most prokaryotes have a cell wall, there are
exceptions such as
Mycoplasma

(bacteria) and
Thermoplasma

(archaea).
The cell wall consists of
peptidoglycan
in.bacteria, and acts as an
addit
ional barrier against exteri
or
forces. It also prevents the cell from
expanding an
d finally bursting (cytolysis)
from
osmotic pressure

against
a hypotonic

environment.
















Diagram of a typical prokaryotic cell