Introduction to Microbiology revised.ppt

Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Content Outline
•Introduction
•What is microbiology?
•Why study microbiology?
•Themes in Microbiology
•Pioneers in the science of microbiology
•Careers in microbiology

What is Microbiology?
• Biology is the study of living organisms
• Microbiology is an advanced biology course
• Microbiology is the study of microbes, which are
extremely small (microscopic) living organisms and
certain non-living entities
• Living microbes are known as cellular microbes or
microorganisms; examples include bacteria, archaea,
some algae, protozoa, and some fungi
• Non-living microbes are known as acellular microbes or
infectious particles; examples include viroids, prions,
and viruses
• Microorganisms are ubiquitous (they are found virtually
everywhere)

Acellular and Cellular Microbes

• The microbes that cause
disease are sometimes
referred to as “germs”
• The scientific term for
disease-causing microbes
is pathogens
• Microbes that do not
cause disease are called
nonpathogens; the vast
majority of microbes are
nonpathogens

• Microbes that live on and in our bodies are
referred to as our indigenous microflora
• Some members of our indigenous
microflora are opportunistic pathogens
• Opportunistic pathogens are microbes that
can cause disease, but usually do not;
they can be thought of as microbes that
are awaiting the opportunity to cause
disease
• Pathogens cause two categories of
diseases: infectious diseases and microbial
intoxications

Categories of Diseases Caused by Pathogens

Why Study Microbiology?
• Microorganisms play significant roles in our
lives; they are essential for life on this
planet
1. Photosynthetic algae and bacteria (such as
cyanobacteria) produce much of the oxygen
in our atmosphere
2. Microorganisms are involved in the
decomposition of dead organisms and waste
products
3. Saprophytes are organisms that live on
dead and/or decaying organic matter
4. The use of microbes to clean up toxic
wastes and other industrial waste products is
known as bioremediation

Microbes as Saprophytes

5. Many microbes play essential roles in various
elemental cycles; e.g., the carbon, nitrogen,
oxygen, sulfur, and phosphorous cycles
6. Algae and bacteria serve as food for tiny
animals; they are important links in food chains
7. Microbes that live in the intestinal tracts of
animals aid in the digestion of food and produce
beneficial substances
8. For many years, microorganisms have been
used as “cell models”; the more that scientists
learned about microbial cells, the more they
learned about cells in general

Microbes and Nitrogen Fixation

ORGANISM CELLULAR
PROCESS
ES
HUMAN
DISEASES
Eschericia
coli
DNA
repair
Colon
cancer and
other
cancers

9. Microbes are used in many industries; e.g.,
food, beverage, chemical, and antibiotic
industries and in genetic engineering
 In genetic engineering, a gene or genes
from one organism is/are inserted into a
bacterial or yeast cell; the cell that receives
the new gene(s) is then capable of
producing the gene product(s) coded for by
the new gene(s)
 The use of living organisms or their
derivatives to make or modify useful
products or processes is call biotechnology

CATEGORIES OF
PRODUCTS/SERVICES
PRESENTLY AVAILABLE
THRU THE USE OF
MICROORGANISMS

MICROBIAL CELL(BIOMASS)
 Live  Baker’s yeast,
 test-cultures for
microbiological assays
 Dead or processed  Yeast autolysates,
 single cell protein

ENZYMES
Invertase
Pectin esterase
Rennin

METABOLITES
 Primary Metabolites  Vitamins,
 Ethanol
 Amino acids
 Secondary Metabolites  Antibiotics
 Citric Acid
 Polysaccharides

TRANSFORMED
PRODUCTS
Semi-synthetic
Penicillins

BIOFERTILIZERS
Microbial
Inoculants
Rhizobium
Mycorrhiza

BIOPESTICIDES
 Microbial Inoculants  Bacillus thuringensis
against Lepidopterans
 Paenibacillus popilliae
against Coleopterans

WASTE DEGRADATION  Sewage treatment by
fermentation/digestion

OTHER PRODUCTS OF MICROBIAL
ACTIVITY
BEVERAGES Wine and Beer
FOODS Cheeses, Pickles,
Fermented Milks, Soy
Sauce, Fish Paste,
Vinegar
FLAVORING AGENTS Monosodium
Glutamate
ORGANIC SOLVENTS Acetone, Butanol,
Ethanol

Microbiology as a BASIC
Biological Science

Microbiology as an APPLIED
Biological Science

* Human insulin can now be manufactured in the
bacteria E. coli in an industrial scale.
•* Human growth hormone, previously isolated
from cadavers, is also manufactured in bacterial
cells
Bt corn – resistance from the corn borer is due to
the insertion of a gene from the bacteria, Bacillus
thuringensis.

Microbiology in
Historical Context

The Discovery of
Microorganisms

Antoni van Leeuwenhoek
• The first person to see bacteria, the
smallest microbial cells, which he
termed “wee animalcules,”
• He constructed extremely simple
microscopes containing a single lens to
examine various natural substances for
microorganisms
• He discovered bacteria in 1676 while
studying pepper–water infusions,

Ferdinand Cohn
• His interests in microscopy led him to
the study of unicellular algae and later to
bacteria, including the large sulfur
bacterium Beggiatoa
• particularly interested in heat resistance
in bacteria, which led to his discovery
that some bacteria form
ENDOSPORES.

Ferdinand Cohn
• Cohn also described the life cycle of the
endospore-forming bacterium Bacillus
and showed that vegetative cells but not
endospores were killed by boiling.
• Cohn also laid the groundwork for a
system of bacterial classification
• He devised effective methods for
preventing the contamination of culture
media, such as the use of cotton for
closing flasks and tubes.

• a French chemist who made
numerous contributions to the newly
emerging field of microbiology and, in
fact, his contributions are considered
by many people to be the foundation of
the science of microbiology and a
cornerstone of modern medicine.
Louis Pasteur

Louis Pasteur
• One of the first to recognize the
significance of OPTICAL ISOMERS.
• Pasteur discovered that the mold
Aspergillus metabolized D-tartrate, which
bent light to the right, but did not
metabolize its optical isomer, L-tartrate
• He began to suspect that some chemical
activities were catalyzed by
microorganisms.

Louis Pasteur
• Pasteur initiated studies on the
mechanism of ALCOHOLIC
FERMENTATION.
• The yeast cells were thought to be
chemical substance formed by the
fermentation.
• Microscopic observations and
experiments convinced Pasteur that
alcoholic fermentation was catalyzed by
living microorganisms, the YEAST
CELLS.

Louis Pasteur
• Pasteur also developed
vaccines for anthrax, fowl
cholera, and rabies.
• Pasteur’s work on rabies was
the most famous success.

Louis Pasteur with Joseph Meister, the first human to receive
Pasteur's rabies vaccination.

What is Spontaneous Generation?
• Living organisms could develop from nonliving matter.

Lazzaro Spallanzani
• Modified Needham’s experiment by using
sealed glass flasks that contained water
and seeds and then placed the flasks in
boiling water.
• He found that no growth took place as
long as the flasks remained sealed.
• He proposed that air carried germs to the
culture medium but also commented that
external air might be required for growth
of animals already in the medium.

Louis Pasteur
• He found out that extensive heating of a
nutrient solution followed sealing it
prevented the growth of microorganisms
• He ended the Theory of
Spontaneous Generation by using
the ”Swan Neck” flask (Pasteur
Flask) in one of his experiments

Infectious Diseases
and Koch’s Postulates

Robert Koch
 a German physician, made numerous
contributions to the science of
microbiology
a. Koch made many significant contributions
to the germ theory of disease.
For example, he proved that the anthrax
bacillus (B. anthracis), which had been
discovered earlier by other scientists, was
truly the cause of anthrax. He accomplished
this using a series of scientific steps that he
and his colleagues had developed; these
steps later became known as Koch’s
Postulates

b. he discovered that B. anthracis produces spores,
capable of resisting adverse conditions.
c. developed methods of fixing, staining, and
photographing bacteria. as well as cultivating
bacteria on solid media. One of Koch’s colleagues,
R.J. Petri, invented a flat glass dish (now known as
a Petri dish) in which to culture bacteria on solid
media. It was Frau Hesse—the wife of another of
Koch’s colleagues—who suggested the use of agar
(a polysaccharide obtained from seaweed) as a
solidifying agent. These methods enabled Koch to
obtain pure cultures of bacteria.

 d. Koch discovered the
bacterium (M. tuberculosis)
that causes tuberculosis
and the bacterium (Vibrio
cholerae) that causes
cholera. •
 Koch’s work on tuberculin
(a protein derived from M.
tuberculosis) ultimately led
to the development of a
skin test valuable in
diagnosing tuberculosis.

Careers in Microbiology
• A microbiologist is a scientist who studies
microbes.
• There are many career fields within the science of
microbiology
1. Bacteriology - bacteria
2. Phycology - algae
3. Protozoology - protozoans
4. Mycology - fungi
5. Parasitology - parasites
6. Virology - virus

Other Career Fields
• Medical Microbiology
– Involves the study of pathogens, the disease
they cause and the body’s defenses against
disease.
– Concerned with epidemiology, transmission of
pathogens, disease-prevention measures,
aseptic techniques, treatment of infectious
diseases, immunology, and production of
vaccines.

• Clinical microbiology or diagnostic
microbiology
- a branch of medical microbiology
- Concerned with the laboratory diagnosis of
infectious diseases of humans.

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