Lecture No.

1
Subject: Microbiology
Course Code: BOTN4128
Contents
 Introduction to Microbiology
 Importance of Microbiology
 Microbiology as a field of biology
 Groups of Microorganism
Introduction to
What is Microbiology?
Microbiology
Microbiology -The science of microorganisms (very small, unicellular
organisms).
Microbiology is the study of microorganisms usually less than 1mm in diameter
which requires some form of magnification ( Microscope) to be seen clearly.
Microorganisms or microbes- these microscopic organisms Commonly called “germs,
viruses, agents…” but not all cause disease and many more are useful or essential for
human life.
Microbiology may be interested in specific types of organisms:
Virology - viruses
Bacteriology - bacteria
Phycology - algae
Mycology - fungi
Protozoology - protozoa
Introduction to Microbiology
Importance of Microbiology
Importance of Microbiology
Importance of Microbiology
Importance of Microbiology
 Microbiology as a field of biology
Microorganisms are exceptionally attractive models for life processes. They can be grown
conventionally
in the test tubes or flasks requiring less space and maintenance than larger plants and

animals. They grow rapidly and reproduce at an usually high rate, some species of

bacteria undergo almost 100 generations in a 24-hour period.

Metabolic processes of microorganisms follow patterns that occur among higher plants

and animals. In fact, the mechanisms by which the organisms (or their cells) utilize energy

are same throughout the biological world. Some microorganisms have the unique ability of

using either radiant energy or chemical energy and thus are like both plants and animals.

Furthermore, some microorganisms, the bacteria in particular are able to utilize a great variety

of chemical substances as their energy source— ranging from simple inorganic substances

to complex organic substances.

 In microbiology we can study organisms in great detail and observe their life

processes while they are actively metabolizing, growing, reproducing, aging,

and dying. By modifying their environment we can alter metabolic activities,

regulate, growth, and even change some details of their genetic pattern—all

without destroying the organisms

Microorganisms have a wider range of physiological and biochemical potentialities
than-all other organisms combined. For example some bacteria are able to utilize
atmospheric nitrogen for the synthesis of proteins and other complex organic
nitrogenous compounds. Other species require inorganic or organic nitrogen
compounds as the initial building blocks for their nitrogenous constituents.

Some microorganisms synthesize all their vitamins, while others need to be furnished
vitamins. By reviewing the nutritional requirements of a large collection of
microorganisms, it is possible to arrange them from those with the simplest to those
with the most complex requirements.
Groups of Microorganism
Bacteriology (Bacteria)
The majority of bacteria (singular: bacterium) are single-celled organisms.
Symmetry: Spherical (cocci), rod (bacilli), or spiral shapes (spirochete), and
comma shape (vibrios) but a few types formfilaments.
Most are so small they can be seen with a light microscope only under the
highest magnification.
Nuclear material and organelles: Although bacteria are cellular, they do not
have a cell nucleus, and they lack the membrane-enclosed intracellular
structures found in most other cells.
Nutrition: Many bacteria absorb nutrients from their environment, but some
make their own nutrients by photosynthesis or other synthetic processes. They
are classify on the basis of nutrition like: Autotrophic bacteria
(photosynthetic bacteria and organotrophic bacteria), Heterotrophic bacteria,
facultative bacteria, chemosynthetic bacteria, and microaerophilic
bacteria.
Nutrition: Many bacteria absorb nutrients from their environment, but
some make their own nutrients by photosynthesis or other synthetic
processes. They are classify on the basis of nutrition like: Autotrophic
bacteria (photosynthetic bacteria and organotrophic bacteria),
Heterotrophic bacteria, facultative bacteria, chemosynthetic
bacteria, and microaerophilic bacteria.
Locomotion: Some are stationary, and others move about. They also
classify on the basis of having flagella. Like: atrichous, monotrichous,
lophotrichous, paritrichous and amphitrichous)
Bacteria are widely distributed in nature, for example, in aquatic
environments and in decaying matter.And some occasionally cause
diseases.
In contrast to bacteria, several groups of microorganisms consist of
larger, more complex cells that have a cell nucleus. They include algae,
fungi, and protozoa, all of which can easily be seen with a light
microscope.
Phycology (Algae)

Many algae (al′je; singular: alga) are single-celled microscopicorganisms, but

some marine algae are large, relatively complex, multicellular organisms.
Nuclear material and organelles: Unlike bacteria, algae have a clearly
defined cell nucleus and numerous membrane-enclosed intracellular structures.
Nutrition: All algae photosynthesize their own food as plants do.
Locomotion: Algae are widely distributed in both fresh water and oceans, and
many can move about.
Because they are so numerous and because they capture energy from sunlight
in the food they make, algae are an important source of food for other
organisms.
Algae are of little medical importance; only one species, Prototheca, has been
found to cause disease in humans. Having lost its chlorophyll, and therefore the
ability to produce its own food, it now makes meals of humans.
Mycology (Fungi)
Fungi (fun′ji; singular: fungus), such as yeasts and some molds,
are single-celled microscopic organisms. Some, such as
mushrooms, are multicellular, macroscopic organisms.
Nuclear material and organelles: Fungi also have a cell nucleus
and intracellular structures.
Nutrition: All fungi absorb ready-made nutrients from their
environment.
Locomotion: Some fungi form extensive networks of branching
filaments, but the organisms themselves generally do not move.
Importance of fungi: Fungi are widely distributed in water and
soil as decomposers of dead organisms. Some are important in
medicine either as agents of diseases such as ringworm and
vaginal yeast infections or as sources of antibiotics.
Protozoology(Protozoa)
Protozoa (pro-to-zo′ah; singular: protozoan) also are single-
celled, microscopic organisms
Nuclear material and organelles: having at least one nucleus
and numerous intracellular structures. A few species of amoebae
are large enough to be seen with the naked eye, but we can study
their structure only with a microscope.
Nutrtion: Many protozoa obtain food by engulfing or ingesting
smaller microorganisms.
Locomotion: Most protozoa can move, but a few, especially
those that cause plant disease, cannot. Protozoa are found in a
variety of water and soil environments, as well as in animals such
as malaria-carrying mosquitoes.
Parasitology (Parasites)

Parasitology is a wide field of microbiology that deals with the study of parasites.
For the most part, parasitology is concerned with organisms found in three major
groups including protozoa, helminths (worms) and arthropods.

Given that parasitology is concerned with disease-causing organisms (as well as

vectors) it has been influenced by a number of other disciplines including
immunology and biochemistry among others. Like mycology and phycology,
parasitology entails the study of both unicellular and multicellular organisms.

Those who study parasitology are known as parasitologists.

Virology (Viruses)
Viruses are acellular entities too small to be seen with a light microscope.
Nuclear material and organelles: They are composed of specific chemical
substances—a nucleic acid and a few proteins b. Indeed, some viruses can be
crystallized and stored in a container on a shelf for years, but they retain the
ability to invadecells.
Replication: Viruses replicate themselves and display other properties of
living organisms only when they have invaded cells. Lytic cycle and lysogenic
cycle. Many viruses can invade plants and cause disease.
Viroids and prions: Even smaller acellular agents of disease are viroids
(nucleic acid without a protein coating), and prions (protein without any
nucleic acid). Viroids have been shown to cause various plant diseases,
whereas prions cause mad cow disease and related disorders.
In addition to organisms properly in the domain of microbiology,
in this text we consider some macroscopic helminths (worms) and
arthropods (insects and similar organisms). The helminths have
microscopic stages in their life cycles that can cause disease, and
the arthropods can transmit these stages, as well as other disease-
causing microbes
Concluding Remarks
s