INTRODUCTION TO MICROBIOLOGY.pptx

MICROBIOLOGY
MR. ABURA GEOFFREY
(BSM, RM, PGDME, Msc. MCB)
aburageoffrey9@gmail.com
0789168556/0761811944

Definitions of key terms used in microbiology
• Microbiology: Is derived from the science (logos) or small (micro) life (bios).
Therefore; microbiology is the study of living things so small that they cannot be
seen with the naked eye.
• Organisms: Any complex thing with properties normally associated with living
things.
• Microorganisms: An organism that is too small to be seen by the unaided eye
(naked eye) such as bacteria.
• Microscope: An optical instrument used for observing small objects.
• Antibiotics: Any substance that can destroy or inhibit the growth of bacteria and
similar microorganisms.
• Antiseptics: Substances that inhibit the growth and reproduction of
microorganism.

Con’t
• The study of microbiology focuses on;
Structure
Form
Physiology
Identification
Metabolism

Microbesin our lives
 Microorganism is important in the maintenance of an ecological
balance on earth (Bioremediation, Nutrient cycling: Nitrogen fixation,
decomposition)
 Some microorganisms live in humans and other animals and are
needed to maintain the animal’shealth.
 Some microorganismsare used to produce foodsand chemicals(cheese,
yogurt, yogurt drinks, chocolate,Alcoholic beverages, Baked foods e.t.c)
 Some microorganisms cause diseases.

HISTORY OF MICROORGANISMS
 It is generally believed that microorganisms have existed on earth for
several billion years. However, until a few hundred years ago, nobody
knew that they existed.
 On the basis that ‘seeing is believing it was only when we had the
means to see microorganisms under a microscope that we could prove
their existence.
 When Antoni van Leeuwenhoek started out on his pioneering
microscope work in 1673.

The First Observation
• 1665 - Robert Hooke reported that living things were composed
of little boxes or cells.
• Hooke's discovery marked the beginning of the cell theory
• Hooke's microscope lacked the resolution to view microbes

ANTONY VAN LEEUWENHOEK (1673-1723)
• He was the first Person, who invented the microscope and discovered the
microbial world. He was a Merchant from Delft, Holland.
• The microscopes of Leeuwenhoek could magnify objects about 200-300 times.
With his microscopes, Leeuwenhoek observed a variety of things like rain water,
pond water and scrapings from his own teeth.
• He saw minute moving objects and called them as “Little animalcules”, which
we now know as protozoa, yeasts and bacteria. He made accurate sketches
and communicated his findings to “Royal Society of London”.
• Thus, Leeuwenhoek was the first person to discover microscope and the
presence of bacteria and spirochetes in mouth.

Microscope of Antony van Leeuwenhoek
Antony van Leeuwenhoek
(1673-1723) - Gave detailed
drawings of what he observed
in teeth scrapings, rain water,
faeces. He called them
"animalcules".

Con’t
• Where did these
creatures come from?
1.Spontaneous Generation
(this was a Myth)
2.Biogenesis theory.

Theory of Spontaneous Generation (ABIOGENESIS)
• After the discovery of microorganisms by Leeuwenhoek, until the 2nd
half of the 19th century, many scientists and philosophers believed
that some forms of life could arise spontaneously from non-living
matter.
• Since organic matter decomposes quickly outside the living body, it
was assumed that microorganisms were arising by spontaneous
generation.

Spontaneous Generation
• It was generally believed that;
 Snakes arose from horse hairs in stagnant water.
 Mice arose from grain and cheese wrapped in a sweater.
 Maggots arose from rotting meat.
 Flies arose from fresh and rotting fruit
 Mosquitoes arose from stagnant pond water
 Locusts arose from green leaves
 Termites are generated from rotting wood

Con’t
• Francisco Redi (1668): A strong opponent of spontaneous generation.
• In an elegant experiment, the Italian Francesco Redi (1626–1697) showed that
the larvae found on putrefying meat arose from eggs deposited by flies, and not
spontaneously as a result of the decay process.
• To confirm his evidence, He prepared 3 jars each with a piece of meat and
covered with fine net.
• After some time, there were no maggots in those jars. He then prepared other 3
open jars with a piece of meat inside them. After some time, Maggots appeared

Conditions Results
3 jars covered with fine net No maggots
3 open jars Maggots appeared
From where did the maggots come?
What was the purpose of the sealed jars?
Redi’s proof was seen as the beginning of the end for the
spontaneous generation theory, but many still clung to the idea,
claiming that while it may not have been true for larger organisms, it
must surely be so for minute creatures such as those demonstrated by
Leeuwenhoek

Conditions Results
Nutrient broth heated, then placed in unsealed
flask
Microbial growth
From where did the microbes come?
John Needham (1745): Supported spontaneous generation theory
Needham claimed the "vital force" necessary for
spontaneous generation had been destroyed by the heat
&was kept out of the flasks by the seals.

Conditions Results
Nutrient broth placed in flask,
heated, then sealed
No microbial growth
From where did the microbes come?
Lazzaro Spallanzani (1765): Disapproved spontaneous generation theory
Anton Laurent Lavoisier discovered the importance of O2 to life of
organisms.
Spallanzani's observations were criticized on the grounds that there
was not enough O2 in the scaled flasks to support microbial life.

The Theory of Biogenesis
• The issue of spontaneous generation was still unresolved in
1858, when Rudolf Virchow challenged the case for
spontaneous generation with the concept of biogenesis (that
the living organisms arise from preexisting life).
• Arguments about spontaneous generation continued until
1861, when the issue was resolved by Louis Pasteur.

LOUIS PASTEUR (1822-1895)
• He was a Professor of Chemistry at the University of Lille, France. He is considered as
“Father of Microbiology”, as his contribution led to the development of Microbiology
as a separate scientific discipline.
• He proved the theory of “Biogenesis” and disproved the “Theory of spontaneous
generation” (Abiogenesis), experimentally by using swan-necked flasks.
• He worked on souring of wine and beer and found that this alcohol spoilage is due to
the growth of undesirable organisms, while the desirable microorganisms produce
alcohol by a chemical process called “Fermentation”. He showed that wine did not
spoil, if it is heated to 50-60°C for a few minutes.
• This method is called “Pasteurization”, now widely used in dairy units, to kill
pathogenic microorganism in milk

• He is a founder of “Germ theory of disease” as he visualized that diseases are caused by
microorganisms.
• In course of his research, he discovered the importance of sterilization and discovered steam
steri-lizer, autoclave and hot air oven.
• He also established the importance of cotton wool plugs for protection of culture media from
aerial contamination.
• He differentiated between aerobic and anaerobic bacteria and coined the term “anaerobic” to
refer to the organisms that do not require oxygen for growth.
• He developed the process of “attenuation” during his work on “chicken cholera” in fowls.
• He found that cultures which had been stored in the laboratory for sometime would not kill the
animals as fresh cultures did. This attenuation is now used in protective vaccination against
diseases.

Conditions Results
heated, not sealed
Microbial growth
heated, then sealed.
No microbial growth
Where did the microbes come from?

Con’t
 Pasteur was fortunate to have worked with broths prepared from non-soil or -
plant associated substances (e.g., hay).
 Those substances (non-soil or –plant) contain bacteria that can form
endospores, not all bacteria can. Endospores represent a bacterial durable
state and are very difficult to kill.
 John Tyndal (1876) discovered that there exist differences in the ability of heat
to kill different kinds of bacteria-containing cultures.
 Ferdinand Cohn (1876) showed that this difference was due to endospores and
Robert Koch (1877) showed that the bacterium Bacillus anthracis forms
endospores as part of its transmission.

The Golden Age of Microbiology
 The period 1857 - 1914 has been appropriately named the Golden Age of
Microbiology.
 During this period, rapid advances, led to the establishment of
microbiology as a science.
Some of the major events that occurred during the Golden Age of
Microbiology include:
1. Fermentation and Pasteurization
2. The Germ Theory of Disease
3. Vaccination
4. The Birth of Modern Chemotherapy

Fermentation & Pasteurization
Pasteur showed that;
Yeasts - responsible of converting sugar to alcohol in
absence of air (fermentation)
Bacteria - cause spoilage by using alcohol to produce
acetic acid (vinegar) in presence of air
Pasteur demonstrated that these spoilage bacteria
could be killed by heat that was not hot enough to
evaporate the alcohol in wine. (pasteurization)
This application of a high heat for a short time is
called pasteurization.

The Germ Theory of Disease
The realization that yeasts play a crucial role in fermentation was the first link between the activity
of a microorganism & physical & chemical changes in organic materials.
This discovery alerted scientists to the possibility that microorganisms might have similar
relationships with plants and animals –specifically that they might cause disease. This idea that
microorganisms might cause disease was known as the germ theory of disease.
This theory was a difficult concept for many people to accept at that time because for centuries
disease was believed to be punishment for an individual's crimes.
The 1st proof that bacteria actually cause disease came from Robert Koch (1876)
He provided proof that a bacterium (Bacillus anthracis) causes anthrax
He provided experimental steps used to prove that a specific microbe causes a specific disease
(Koch’s postulates):

He provided proof that a bacterium causes anthrax and
provided the experimental steps, Koch’s postulates, used
to prove that a specific microbe causes a specific
disease;
(a) Pathogen must be present in all cases of disease
(b) Pathogen must be isolated and grown in lab in pure culture
(c) Pathogen from pure cultures must cause disease when
inoculated into healthy, susceptible lab animal
(d) Same pathogen must be isolated from the diseased lab animal
 Once established, Koch’s postulates helped determine the
causative agents of other infectious diseases.

Exceptions to Koch’s postulates
Some microbes are very difficult or impossible to grow in vitro(in
the laboratory) in artificial media. E.g. Treponema pallidum
Many species are species specific. E.g. Brucella abortus cause
abortion in animals but no report in humans.
Certain diseases develop only when an opportunistic pathogen
invades immunocompromised host.

Major achievements of Robert Koch
Discovery and use of solid medium in
bacteriology
Discovery of causative agents of tuberculosis
and cholera.
Koch’s phenomenon
Koch’s postulates

Vaccination
In a vaccination, immunity is conferred by inoculation with a vaccine.
In 1798, Edward Jenner demonstrated that inoculation with cow-pox
material provides humans with immunity to smallpox.
About 1880, Pasteur discovered that a virulent bacterium could be
used as a vaccine for fowl cholera; he coined the word vaccine.
Modern vaccines are prepared from living a virulent-microbes or
killed pathogens.

EDWARD JENNER (1749-1823)
• Jenner was an English country physician, who discovered a safe and efficient
vaccination against small pox. This ultimately led to the eradication of small
pox (Variola).
• Jenner observed that dairy workers, exposed to occupational cowpox infection
were immune to small pox. He proved experimentally that resistance to small
pox can be induced by injecting cow pox material (Vaccinia) from disease
pustules into man (in 1796).
• Pasteur gave the general term “Vaccine” (Vacca = cow) in honour of Jenner’s
cow pox vaccine, to various materials used to induce active immunity. Jenner
published his findings in 1798 in a pamphlet “An inquiry into the cause and
effect of variole vaccine”.

Small pox vaccine by Jenner
The smallpox vaccine, introduced by
Edward Jenner in 1796, was the first
successful vaccine to be developed.
He observed that milkmaids who
previously had caught cowpox did not
catch smallpox and showed that
inoculated vaccinia protected against
inoculated variola virus.

History of immunology –
Edward jenner

History of immunology
LUIS PASTUER: He is renowned for
his discoveries of the principles
of vaccination, cholera, rabies and
anthrax

Emil Von Behring (1854-1917)
• Emil Von Behring (Humoral Immunity) Injected inactivated toxin
to Rabbit inducing them to produce soluble substance in the blood
called antitoxin- a substance that inactivate toxin and protect
against diseases antibodies.

METCHNIKOFF (1845-1916)
• Elie Metchnikoff (Cellular Immunity), the Russian-French biologist, discovered
the phenomenon of phagocytosis, the cellular concept of immunity. In Italy, where
he had gone on a research visit, he studied the transparent larvae of starfish and
noticed some of their cells could engulf and digest foreign protein particles.
• These cell eaters are called “Phagocytes”. He continued his work on phagocytic
action, at Pasteur Institute and found that in human blood a large proportion of
the leucocytes (White blood cells) are phagocytic and attack invading bacteria.
• This, in turn, results in increased numbers of leucocytes in the infected areas
followed by the inflamed area becoming hot, red, swelled and painful due to dead
phagocytes forming pus.

Chemotherapy
• 1910: Paul Ehrlich developed a synthetic arsenic drug, salvarsan,
to treat syphilis.
• 1928: Alexander Fleming discovered penicillin from Penicillium
notatum (later renamed Penicillium chrysogenum)
• 1930s: Sulfonamides were synthesized.

SIR FRANK MAC FARLANE BURNET (1967)
• Burnet is an Australian scientist, won nobel prize for the discovery of acquired
immunological tolerance. He proposed clonal selection theory to explain
antibody synthesis.
• His work on bacteriophages and method for culturing some viruses in live chick
embryo, led him to the view that an animal’s ability is not inborn, but is
developed during fetal life.
• Burnet (1967) developed concept of “immunological surveillance”, according
to which the primary function of the immune system is to preserve the integrity
of the body, seeking and destroying all “foreign” antigens, whether autogenous
or external in origin.

Modern Developments in Microbiology
• Groundwork laid during the Golden Age of
Microbiology provided the basis for several
monumental achievements during the 20th century

ASSIGNMENT
Ignaz Semmelweis (1850)-Child birth fever
IWANOWSKY (1892)- virus
JOSEPH LISTER (1827-1912)-Spray Phenol (Post
operation disinfection)

BRANCHES OF MICROBIOLOGY
1. Medical microbiology
2. Industrial microbiology
3. Agricultural microbiology
4. Veterinary microbiology
5. Food microbiology
6. Soil and plant microbiology

BRANCHES OF MEDICAL MICROBIOLOGY
1. Bacteriology – it is the science of pathogenic bacteria. It also refers to the scientific study of
bacteria.
2. Virology – the science of infectious viruses.
3. Protozoology – it is the study of pathogenic protozoa.
4. Mycology – the study of fungi which are pathogenic to man.
5. Parasitology – this is the study of parasites (i.e. protozoa and helminths)
6. Helminthology – study of Helminthes (worms)
7. Entomology – is the study of insects (vectors) that transmit diseases to man.
8. Serology – the study of the reaction between antigens and antibodies
9. Immunology- the study of immunity

Why is microbiology an important subject?
• 1. Disease causation: Microorganisms cause disease due to their qualities of
Invasiveness & Toxigenesis. For example, health workers must be able to protect patients
from common microbes that are normally harmless but pose a threat to the sick and
injured.
• 2. Normal microbiota (normal flora): Humans and many other animals depend on the
microbes that live on & inside our bodies without causing harm in many ways. For
example:
 Those found within the GIT help in digestion &synthesis of some vitamins that their
bodies require, e.g. some B vitamins for metabolism & vitamin K for blood clotting.
 They protect us against disease by preventing adherence of invading organisms,
consuming available nutrients & producing toxic compounds that invade other
organisms
 They prime the adaptive immune system
Note: Under some circumstances normal microbiota can infect us or those we contact e.g.
when they change their habitat.

Industrial Use:
 Microorganisms also have many commercial applications.
 They are used in the synthesis of such chemical products as vitamins, organic acids,
enzymes, alcohols, high-fructose syrups, paper, ink etc.
 For example:
- Amylases are used in the production of syrups from corn starch, in the production
of paper sizing, and in the production of glucose from starch
- Gluconacetobacter xylinus bacteria produce denim blue jeans
- Polyhydroxy alkanoate (PHA) produced by some microbes are used to make
paper bags

Agricultural use:
 By using microbial rather than chemical insect control, farmers can avoid harming the
environment.
 Many chemical insecticides, such as DDT, remain in the soil as toxic pollutants and are
eventually incorporated into the food chain
 For example, Bacillus thuringiens is used extensively to control pests such as alfalfa
caterpillars, corn borers, cabbage worms etc
- It is incorporated into a dusting powder that is applied to the crops these insects
eat.
- The bacteria produce protein crystals that are toxic to the digestive systems of the
insects.
 Also, a toxin gene has been inserted into some plants to make them insect resistant.

Food production;
 The food industry also uses microbes in producing many products.
Dairy products such as cheese, butter, yogurt, Kefir and kumiss
Non-dairy products such as sauerkrallt (made from Digestion of
carbs in cabbage) pickles, olives, cocoa & coffee
Alcoholic beverages such as wines, beers & distilled spirits
Manufacturing Yeast breads

Pharmaceutical uses;
Microbes are used in the production of products such as antibiotics, alkaloids,
steroids, vaccines
Also, for production of recombinant human proteins, such as insulin, growth
hormone & interferon
Fuel production;
Microbes are used in fermentation to produce ethanol, and in biogas reactors to
produce methane
Currently methane & ethanol are the main fuels from microbial sources, although
there are other potential fuels that could be developed
Scientists are researching the use of algae to produce liquid fuels, and bacteria to
convert various forms of agricultural and urban waste into usable fuels.

Environmental uses;
 Microbes are used to recycle vital elements in the environment
 Chemical elements e.g. carbon, nitrogen, oxygen, sulfur, etc are abundant &
essential for life, but are not necessarily in forms that organisms can use.
 Microorganisms convert these elements into forms that plants & animals can
use.
 Only bacteria can naturally convert atmospheric nitrogen to a form available to
plants and animals. They decompose organic wastes, dead plants and animals.
 Algae, cyanobacteria, and higher plants use the carbon dioxide during
photosynthesis to produce carbohydrates for animals, fungi, and bacteria.

Bioremediation;
 Use of Microbes to Clean Up Pollutants
 In 1988, scientists began using microbes to clean up pollutants and toxic wastes
produced by various industrial processes.
 For example, some bacteria can actually use pollutants as energy sources; others
produce enzymes that break down toxins into less harmful substances.
 Microbes are used to remove toxins from underground wells, chemical spills, toxic
waste sites, and oil spills
 Additionally, bacterial enzymes are used in drain cleaners to remove clogs without
adding harmful chemicals to the environment.
 Among the most commonly used microbes are certain species of bacteria of the genera
Pseudomonas and Bacillus.

Bio-augmentation;
 Use of microbes in the biological treatment of sewage & industrial waste effluent
 Sewage treatment plants remove the undesirable materials and harmful
microorganisms.
 1st large solids such as paper, wood, glass, gravel, and plastic are removed from
sewage; then the liquid and organic materials are converted by bacteria into
such by-products as carbon dioxide, nitrates, phosphates, sulfates, ammonia,
hydrogen sulfide, and methane.
 Microorganisms e.g. E. coli, K. pneumonia are used as indicators for the
detection effluent water contamination

Bio-mining
Use of microorganisms to leach out metals from ores or mine tailings (wastes), followed by
the recovery of metals of interest from the leaching solution
 Thiobacililis ferrooxidans is used in copper mining
 Scientists have also found microbes such as Anabaena cylindrica could
help mine oxygen, nutrients and minerals in space
Biosensors
 Bacteria that detect pollutants & pathogens. They require both a receptor that is
activated in the presence of pollutants and a receptor that will make such a change
apparent
 Example Lactococcus bacteria are used to detect the presence of antibiotics in milk
that is to be used for cheese production.

THE RELEVANCY OF MICROBIOLOGY TO A NURSE/MIDWIFE
 The nurse/midwife learns how the disease causing organisms (pathogens) enter
the body.
 The nurse/midwife learns how pathogens are discharged from the body and
spread from person to person.
 Equips the nurse/midwife with principles of disinfection and the effects of drugs
on the microbes.
 The knowledge of microbiology enables the nurse/midwife to collect specimens
for laboratory examination.
 It enables the nurse/midwife to interpret results from the laboratory.
 Microbiology enables the nurse/midwife appreciate how sera and vaccines are
prepared and used to treat and prevent diseases and their effects on the human
body.

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