1.
MICROBES are said to be
UBIQUITOUS

2.
• Pathogens
 microbes that cause disease; 3%
of microbes are pathogenic
• Nonpathogens
 microbes that do not cause
disease

3.
WHY STUDY
MICROBIOLOGY?

4.
• Indigenous microbiota
• AKA: Human microbiome
• the microbes that live on and in the human
body
• 10 trillion cells x 10 = 100 trillion microbes
• Opportunistic pathogens
• AKA: Opportunists
• microbes that do not cause disease under
ordinary conditions, but have the potential to
cause disease should the opportunity present
itself

5.
WHY STUDY MICROBIOLOGY?
• Microbes are essential for life
• Algae and cyanobacteria – a group of photosynthetic bacteria that produce oxygen
• Bioremediation –genetically engineered microbes
• Antibiotics – some bacteria and fungi produce antibiotics that are used to treat
patient with infectious diseases
• Genetic engineering - microbes are essential in this field where a gene or genes
from one organism (e.g., from bacterium, a human, an animal, or a plant) is/are
inserted into a bacterial or yeast cell
• Microbes has been used as “cell models”

6.
• Decomposers or Saprophytes
• these microbes break down dead
and decaying organic material into
inorganic nutrients in the soil
• Decomposition
• is the process by which substances
are broken down into simpler forms
of matter

7.
• Microbial ecology
• The study of the relationships
between microbes and the
environment

8.
• Microbes serves as important links in food chains
• Plankton – microscopic organisms in the ocean that
serve as the starting point of many food chains
• Phytoplankton – tiny marine plants and algae
• Zooplankton – tiny marine animals

9.
• Biotechnology
• the use of living organisms or their derivatives to
make or modify useful products or processes

10.
• microbes causes 2
categories of diseases

11.
FIRST MICROORGANISMS ON EARTH
Archaea and
cyanobacteria

12.
EARLIEST KNOWN INFECTIOUS DISEASES
• Bacterial diseases: TB, syphilis
• Parasitic worm infections: schistosomiasis, dracunculiasis (guinea worm infection), tapeworm
• Bubonic plague (around 1900 BC)
• Smallpox (China, 1122 BC)
• Rabies, anthrax, dysentery, smallpox, ergotism, botulism, measles, typhoid fever, typhus fever,
diphtheria
• Syphilis (Europe, 1493) – AKA: Spanish, German, Polish and Turkish pox
• In French – Neapolitan disease
• In Italian – French or Spanish disease
• In English – French Pox

13.
PIONEERS IN THE SCIENCE OF MICROBIOLOGY
• Anton Van Leeuwenhoek
• (1632 – 1723)
• Father of Microbiology, Father of
Bacteriology, Father of Protozoology
• Single-lens microscope or simple
microscopes
• “animalcules”
• ROBERT HOOKE
• 1635-1703

14.
PIONEERS IN THE SCIENCE OF MICROBIOLOGY
• Theory of spontaneous generation
• AKA: Abiogenesis
• accdg to leeuwenhoek in this theory that “Life can arise spontaneously from
nonliving material”
• Louis Pasteur and John Tyndall
• disproved the theory of spontaneous generation and proved that life can only arise
from preexisting life (Theory of Biogenesis)
• Rudolf Virchow
• German scientist who first proposed the theory of biogenesis

15.
PIONEERS IN THE SCIENCE OF MICROBIOLOGY
• Louis Pasteur (1822-1895)
• a French chemist who made numerous
contributions to the newly emerging field of
microbiology
• His most significant contributions:
• Fermentation
• Yeasts convert the glucose in grapes to ethyl
alcohol (ethanol)
• Acetobacter (a bacteria) that convert glucose to
acetic acid (vinegar)

16.
PASTEUR’S CONTRIBUTION
• Theory of spontaneous generation
• “aerobes” and “anaerobes”
• Pasteurization
• a process that kill microbes that were causing
wine to spoil
• Discovered the infectious agents that cause
the silkworm disease
• Germ theory of disease
• Anthrax (Bacillus anthracis)
• Tuberculosis (Mycobacterium
tuberculosis)
• Hospital practices
• Developed vaccines
• Vaccines to prevent rabies in dogs

17.
PIONEERS IN THE SCIENCE OF MICROBIOLOGY
• Robert Koch (1843 – 1910)
• a German physician, made numerous
contributions to the science of
microbiology
• His most significant contributions:
• Germ Theory of disease
• Anthrax bacillus (B. anthracis)
• he also discovered that this bacteria
produces spores, capable of resisting
adverse conditions
• Koch’s Postulates

18.
KOCH’S CONTRIBUTION
• Methods of fixing, staining, and photographing
bacteria
• Methods of cultivating bacteria in a solid media
• R.J. Petri – invented a flat glass dish (AKA: Petri
dish) in which to culture bacteria on solid media
• Frau Hesse – who suggested the use of AGAR
(a polysaccharide obtained from seaweed) as a
solidifying agent
• M. tuberculosis and Vibrio cholera
• Tuberculin (a protein derived from M.
tuberculosis)

19.
KOCH’S POSTULATES
• A particular microbe must be found in all cases of
the disease and must not be present in healthy
animals or humans.
• The microbe must be isolated from the diseased
animal or human and grown in pure culture in the
laboratory
• The same disease must be produced when
microbes from the pure culture are inoculated into
healthy susceptible laboratory animals
• The same microbe must be recovered from the
experimentally infected animals and grown again
in pure culture

20.
EXCEPTIONS TO KOCH’S POSTULATES
• Obligate intracellular pathogens
• AKA: Obligate intracellular parasites
• they can survive and multiply only with living host
cells
• e.g. viruses, rickettsias, chlamydias, M. leprae &
Treponema pallidum
• Pathogens are species-specific
• it infect only one species of animal
• Diseases called Synergistic infections or
polymicrobial infections
• are caused not by one particular microbe but by
the combined effects of two or more different
microbes
• e.g. Acute necrotizing ulcerative gingivitis
(AKA: “Trench mouth” and bacterial
vaginosis
• Certain pathogens become altered when
grown in vitro
• some becomes less pathogenic, whereas
others become non-pathogenic
• Thus, they will no longer infect animals after
being cultures on artificial media

21.
CAREERS IN MICROBIOLOGY
• Microbiologist
• a scientist who studies microbes
• Bacteriologist
• a scientist who specializes in bacteriology: the study
of the structures, functions and activities of bacteria
• Phycologists/ Algologists
• scientists specializing in the field of
phycology/algology who study the various types of
algae
• Protozoologists
• who explore the area of protozoology: the study of
protozoa
• Mycologists
• those who specializes in the study of fungi
• Virologists
• who study viruses and their effects on living cells
of all types
• they also study prions and viroids, acellular
infectious agents that are even smaller than
viruses
• Virologists and cell biologists
• may become genetic engineers who transfer
genetic material (DNA) from one cell type to
another