Introduction Definition

1. Lecture 1
Introduction to microbiology
Classification of microorganisms

2. LECTURE OBJECTIVES
1. Microbiology, the science (definition,
types of microbiology)
2. The developing science of microbiology
(history, contributions of scientists)
3. Classification of microorganisms

3. 1. Microbiology, the science
(definition)
• Microbiology
in Greek: micro = small, bio = life, logy = “to
study” or “the study of”
• Microbiology is the science concerned with the
study of living microorganisms.
• Microorganisms (microbes) are small
unicellular or cell-cluster organisms; includes
fungi, protists, bacteria and viruses (though
viruses are not strictly classed as living
organisms).

4. Types of microbiology
• General microbiology: The study and
classification of microorganisms and their
function
• Medical microbiology: The study of
pathogens, the diseases they cause, and the
body’s defences against disease
• Veterinary microbiology: The study of the
role in microbes in veterinary medicine.

5. • Environmental microbiology: The study
of the function and diversity of microbes in
their natural environments, or microbial
ecology.
• Evolutionary microbiology: The study of the
evolution of microbes. Includes the study of
bacterial classification and taxonomy.
• Industrial microbiology: The exploitation of
microbes for use in industrial processes:
industrial fermentation and wastewater
treatment.

6. • Sanitary microbiology analyses and inspects
content of pathogenic microorganisms in air,
water, soil, food, medicines, utensils
• Agricultural microbiology: The study of the
role in microbes - plant pests.
Microbiology is related to biochemistry,
genetics, pathology, immunology,
epidemiology, ecology, biological disciplines

7. 2. The developing science of
microbiology (history,
contributions of scientists)
• Antony van Leeuwenhoek is father of
bacteriology: he who first described the
different shapes of bacteria and pictured
their arrangement in infected material,
using a single-lens microscope of his own
design.
• The name "bacterium" was introduced
much later, by Ehrenberg in 1828, derived
from the Greek word bactēria meaning
"small stick".
• While Antony van Leeuwenhoek is often
cited as the first microbiologist, the first
recorded microbiological observation, that
of the fruiting bodies of molds, was made
earlier in 1665 by Robert Hooke.

8. • Louis Pasteur (1822-1895) and Robert
Koch (1843-1910) were
contemporaries and are often
considered to be the founders of
medical microbiology.
• Pasteur is most famous for his series
of experiments designed to disprove
the widely held theory of spontaneous
generation, thereby solidifying
microbiology’s identity as a biological
science.
• Pasteur also designed methods for
food preservation (pasteurization) and
vaccines against several diseases such
as anthrax, fowl cholera and rabies.

9. • Robert Koch is best known for his
contributions to the germ theory of
disease, proving that specific
diseases were caused by specific
pathogenic microorganisms. He
developed a series of criteria that
have become known as the Koch’s
postulates.
• Koch was one of the first scientists
to focus on the isolation of bacteria
in pure culture resulting in his
description of several novel
bacteria including Mycobacterium
tuberculosis, the causative agent of
tuberculosis.

10. • Martinus Beijerinck (1851-1931) and Sergei
Winogradsky (1856-1953) - the founders of general
microbiology (an older term encompassing aspects of
microbial physiology, diversity and ecology), that the
true breadth of microbiology was revealed.
• Martinus Beijerinck made two major contributions to
microbiology: the discovery of viruses and the
development of enrichment culture techniques.
• Sergei Winogradsky was the first to develop the
concept of chemolithotrophy and to thereby reveal the
essential role played by microorganisms in geochemical
processes. He was responsible for the first isolation and
description of both nitrifying and nitrogen-fixing
bacteria.

11. 3. Classification of microorganisms
•Taxonomy is the
science of
classification. As
a science it is
dynamic and
subject to
change on the
basis of
available data.

12. Classification
•Classification is an orderly
arrangement of bacteria into group
•Identification is the practical use of
classification to isolate and
distinguish desirable organisms from
undesirable ones.

13. Principles
• morphology
• staining
• motility
• growth
• atmospheric requirements
• nutritional requirements
• biochemical and metabolic activities
• pathogenicity
• amino acid sequencing
• genetic composition
Classification of microorganisms

14. • Cell shape
• Gram stain (cell wall structure)
• Growth temperature
• Ability to form heat stable spores
• Electron acceptors for respiration (if any)
• Photosynthetic ability
• Motility
• Ability to use various carbon and nitrogen
sources
• Special nutritional requirements (e.g.,
vitamins)

15. Kingdom and Phylum
Five kingdoms:
• Animalia (for animals)
• Plantae (for plants)
• Fungi (for fungi)
• Protista (for algae and protozoa)
• Procaryotae:
Phylum I - Photobacteria (cyanobacteria)
Phylum II - Scotobacteria (bacteria)

16. Bergey’s Manual of determinative
bacteriology
Kingdom
Phylum
Class
Order
Family
Genus
Species

17. Kingdom Procariotes
Section Scotobacteria
Class Bacteria
Order Eubacteriales
Family Enterobacteriaceae
genus Escherichia
species E.coli

19. Cellular
1. Protists (eucaryotes):
algae, protozoa, fungi, slime molds
2. Procaryotes:
bacteria, cyanobacteria
Non-Cellular
3. Viruses (RNA or DNA+capsid)
4. Viroids (RNA without capsid)
5. Prions (Proteinaceous infectious agents)