Introduction to Microbiology
is the study of microorganisms, a large and diverse group
of microscopic organisms
which must be viewed with a micro
exist as single cells or cell clusters; it also includes viruses, which are
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
Bacteria and some fungi are important in decomposition and recycling
Industry applications of microbiology: waste management, food
industry, mining, medicine, research and biotechnology.
History of Microbiology
he history of microbiology can be summarized in the
observed microorganisms for the first time with
a microscope and coined the term “cell”.
Anton van Leeuwenhoek
having observed the first
First scientific Small pox vaccination
developed the first classification scheme
based on bacteria
Cohn detailed and descr
life cycle of
Bacillus, and he put the first
of bacteria called
Cohn’s Classification System
divided into four groups
Sphaerobacteria are spherically shaped.
Microbacteria are rod shaped
Desmobacteria are filamentous
a are spiral shaped
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
identified anthrax and developed agar growth
Koch’s postulates was a systematic method to establish the
microbial cause of disease.
was the first to recognize the need for good
ng medical procedures.
The first to identify nosocomial
dvocated washing hands to stop the spread of disease
developed antiseptic methods for use in
surgery and medicine.
hemotherapy to cure infectious
diseases and discovers antibiotics to treat sleeping sickness and syphilis
Invented Petri Dish
ed Gram Stain
Recognized viral dependence on cells for reproduction
discovered penicillin and lysozyme.
discovered the first virus which is known
as the tobacco mosaic virus (TMV).
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.
Developed a method to seq
W. Gilbert & F.
Polymerase Chain Reaction invented
First microbial g
enomic sequence published
Anatomy of bacteria
bacterial cell is a
is simpler, and therefore
smaller, than a eukaryote cell, lacking a
and most of the other
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
A prokaryotic cell ha
s three architectural regions:
On the outside
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
generally consisting of a
though some bacteria also have a
further covering layer called a
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
The cell wall consists of
in.bacteria, and acts as an
ional barrier against exteri
forces. It also prevents the cell from
d finally bursting (cytolysis)
Diagram of a typical prokaryotic cell