Microbiology

1. Subject {L-T-P / C} : BM2009 : Microbiology {3-0-0 / 3}
Subject Nature : Theory
Coordinator : Dr. Angana Sarkar
Syllabus: Introduction to microbiology, History of microbiology and notable contribution of eminent scientists,
Classification of bacteria and virus, Ultrastructure of prokaryotes and eukaryotes, Morphology of bacteria and
staining techniques, Cultivation of bacteria – Culture characteristics and Growth pattern, Nutritional and Physical
Requirements, Types of media, Isolation, Maintenance and Preservation of the pure cultures, Batch and Continuous
cultures, Diauxic and Synchronous growth, Enumeration techniques, Mathematical concepts in microbial growth,
Control of growth of Microbes, Lytic and lysogenic life cycles of bacteriophages. Microbial genetics, conjugation,
transformation, transduction. Important microbes in medical sciences and industry.
Essential Reading:
 Pelczar. M., et al.,, Microbiology, 5th ed.,2000, McGraw-Hill
 Prescott, LM., Microbiology, 6th ed. 2005, McGraw-Hill.
Supplementary Reading:
 Atlas, RM., Principles of Microbiology. 2nd ed.,1997, McGraw-Hill
 Salle, AJ.,, Fundamental Principles of Bacteriology, 7th ed.,1999, Tata- McGraw Hill

2. SCOPE AND HISTORY OF
MICROBIOLOGY

3. SCOPE OF MICROBIOLOGY
Microbes:
• The word microbe is short for microorganism, which literally means small organism. Believe it
or not, while microbes have lived without us on this Earth for millions of years, we certainly
could not live without them!
• Collectively, microbes encompass millions of species of bacteria, fungi, algae, protozoa and
viruses.
• Microbes are the oldest form on life on our planet. Scientists have found fossils more than 3.5
million years old that contain remnants of the earliest bacterial-like microbes. Such fossils tells
us that these microscopic organisms were around when the Earth was covered with water,
which often reached boiling point. To put this into perspective, this was hundreds of millions
of years before dinosaurs roamed the Earth.
• Microbes are an extremely diverse group of organisms, and in terms of species numbers they
represent the most abundant life form on this planet.

4. Where Are Microbes Found?
 In a nutshell: everywhere!
 You can find microbes in our mouths and intestines, under our nails, on our skin, in our water, inside plant
roots, on our bed sheets and in compost heaps.
 Some microbes you can see in the form of bread mold, mushrooms, and genital thrush infections, but
most microbes are invisible to the naked eye. In fact, the smallest microbial cells are so small that millions
of them could fit into the full stop at the end of this sentence!
 Microbes are very successful organisms and many can survive in extreme conditions. These are called
extremophiles. Some microbes can survive temperatures above boiling point. Other microbes thrive in
freezing conditions and die at room temperature. Some use other substances than oxygen to produce
energy (e.g., sulfuric acid, iron, arsenic or uranium), while others flourish in chemical environments
 Microbes that live in more moderate conditions are often referred to as mesophiles or neutrophiles.
Many of the microorganisms which are relevant to us as humans fall into the mesophile category.

5. Do you know?
 The human microbiome is the aggregate of all
microbiota that reside on or within human tissues and
biofluids
 The human microbiota consists of the 10-100 trillion
(∼1013–1014 microbial cells) symbiotic microbial cells
harbored by each person
 Present in skin, mammary glands, placenta, seminal
fluid, uterus, ovarian follicles, lung, saliva, oral mucosa,
conjunctiva, biliary tract, gut
 These numbers are derived from the total bacterial cells
in colon (3.8 × 1013 bacteria)
 Firmicutes, Bacteroidetes, and Actinobacteria
 1-3% of body mass
 10 times ore than human body cell
We are never
alone: living
with the Human
Microbiota
Kho & Lal, 2018

6. https://www.insightsonindia.com/2018/12/01/insights-into-
editorial-why-india-wants-to-study-human-microbiome/

7. What is Microbiology?
 Study of living organisms
 Microscopic size
 Structure, reproduction, growth, metabolism, physiology and classification
 Distribution in nature, their relationship to each other, environment and other
living organisms
 Effects on human beings and on other animals and plants
 Effects on environment: physical and chemical changes
Example: Bacteria, fungi, algae, protozoa, viruses

8. Microbiology may be interested in specific types of organisms:
 Virology - viruses
 Bacteriology - bacteria
 Phycology - algae
 Mycology - fungi
 Protozoology - protozoa
 Parasitology - parasites
Various characteristics or activities of microorganisms:
 Microbial morphology
 Microbial cytology
 Microbial physiology
 Microbial ecology
 Microbial genetics and molecular biology
 Microbial taxonomy
Branches of Microbiology:
Genetic Engineering
Molecular Biology
Immunology
Biotechnology

9. Why we should study Microbiology?
 Microorganisms are closely associated with the health and welfare of human beings
 Medical microbiology, including immunology
 Food and Dairy microbiology
 Public Health microbiology (Epidemiology)
 Industrial microbiology
 Agricultural microbiology
Applications:
 Biological roles- decomposers, recyclers, symbionts
 Animal digestion - ruminants, methane
 Food Microbiology - yogurt, sauerkraut, Kim Chee, cheese, beer, bread etc.
 Food safety - prevent putrefaction, disease etc.
 Pharmaceuticals- produce complex drug molecules (ex. insulin )
 Bioremediation - using microbes to clean pollution
 Pathogenicity - bacteria and viruses that make us sick
 Fundamental Biology: most biochemical pathways worked out with microbes
 Medical Biology: Immune system & pathogenicity
 Space Biology: in search of new life
 Industrial Microbiology: enzymes, organic solvents, pigments, biofuels

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A Brief History of Microbiology
• Ancestors of bacteria were the first life on
Earth.
• The first microbes were observed in 1673.
• http://en.wikipedia.org/wiki/Antonie_van_Leeuwenhoek
Robert Hooke (1665): 1st Scope (cell)
Antoine Van Leeuwenhoek (1666): Microbes
Zacharias Janssen (1632): Microscope
Carl Linnaeus (1178): classification
Matthias Schleiden & Theodor Schwann (1839): Cell Theory
Alexander Fleming (1982): Penicillin

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• In 1858, Rudolf Virchow said cells arise from preexisting cells.
• Cell Theory. All living things are composed of cells and come from
preexisting cells
Continues:
Robert Koch(1905): Koch’s postulates
1. The suspected causal organism must be constantly associated with the disease.
2. The suspected causal organism must be isolated from an infected plant (or animals)
and grown in pure culture.
3. When a healthy susceptible host is inoculated with the pathogen from pure culture,
symptoms of the original disease must develop.
4. The same pathogen must be re-isolated from plants (animals) infected under experimental
conditions.

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The Golden Age of Microbiology
• 1857-1914
• Beginning with Pasteur’s work, discoveries included the
relationship between microbes and disease, immunity, and
antimicrobial drugs

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• Pasteur showed that microbes are responsible for
fermentation.
• Fermentation is the conversation of sugar to alcohol
to make beer and wine.
• Microbial growth is also responsible for spoilage of
food.
• Bacteria that use alcohol and produce acetic acid
spoil wine by turning it to vinegar (acetic acid).
• Pasteur demonstrated that these spoilage bacteria
could be killed by heat that was not hot enough to
evaporate the alcohol in wine. This application of a
high heat for a short time is called pasteurization.
Fermentation and Pasteurization (1864)

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• 1835: Agostino Bassi showed a silkworm disease was caused by a fungus.
• 1865: Pasteur believed that another silkworm disease was caused by a
protozoan.
• 1840s: Ignaz Semmelweiss advocated handwashing to prevent transmission
of puerperal fever from one patient to another.
The Germ Theory of Disease

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• 1860s: Joseph Lister used a chemical disinfectant to prevent surgical
wound infections after looking at Pasteur’s work showing microbes are in
the air, can spoil food, and cause animal diseases.
• 1876: Robert Koch 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.
The Germ Theory of Disease
Vaccination
• 1796: Edward Jenner inoculated a person with cowpox virus. The
person was then protected from smallpox.
• Called vaccination from vacca for cow
• The protection is called immunity

16. 16
• Treatment with chemicals is chemotherapy.
• Chemotherapeutic agents used to treat infectious disease can be synthetic
drugs or antibiotics.
• Antibiotics are chemicals produced by bacteria and fungi that inhibit or kill
other microbes.
• Quinine (1820) by Pierre Joseph Pelletier and Joseph Caventou from tree
bark was long used to treat malaria.
• Paul Ehrlich (1910) developed a synthetic arsenic drug, salvarsan, to treat
syphilis.
• Sulfonamides were synthesized by Bayer chemists Josef Klarer and Fritz
Mietzsch (1930s)
The Birth of Modern Chemotherapy

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• 1928: Alexander Fleming discovered
the first antibiotic.
• He observed that Penicillium fungus
made an antibiotic, penicillin, that
killed S. aureus.
• 1940s: Penicillin was tested clinically
and mass produced.
The Birth of Modern Chemotherapy
Figure 1.5

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• Bacteriology is the study of bacteria.
• Mycology is the study of fungi.
• Parasitology is the study of protozoa and parasitic worms.
• Recent advances in genomics, the study of an organism’s genes, have
provided new tools for classifying microorganisms.
• Genome sequencing using Next Generation Sequencing platform
Modern Developments in Microbiology

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• Immunology is the study of
immunity. Vaccines and
interferons are being
investigated to prevent and cure
viral diseases.
• The use of immunology to
identify some bacteria according
to serotypes (variants within a
species) was proposed by
Rebecca Lancefield in 1933.
Modern Developments in Microbiology

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• Virology is the study of viruses.
• Recombinant DNA is DNA made from two different sources.
In the 1960s, Paul Berg inserted animal DNA into bacterial
DNA and the bacteria produced an animal protein.
• Recombinant DNA technology or genetic engineering
involves microbial genetics and molecular biology.
Modern Developments in Microbiology

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• Using microbes
• George Beadle and Edward Tatum showed that genes encode
a cell’s enzymes (1942)
• Oswald Avery, Colin MacLeod, and Maclyn McCarty showed
that DNA was the hereditary material (1944).
• Francois Jacob and Jacques Monod discovered the role of
mRNA in protein synthesis (1961).
Modern Developments in Microbiology

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* The first Nobel Prize in Physiology or Medicine.
Selected Novel Prizes in Physiology or
Medicine
1901* von Behring Diphtheria antitoxin
1902 Ross Malaria transmission
1905 Koch TB bacterium
1908 Metchnikoff Phagocytes
1945 Fleming, Chain, Florey Penicillin
1952 Waksman Streptomycin
1969 Delbrück, Hershey, Luria Viral replication
1987 Tonegawa Antibody genetics
1997 Prusiner Prions

23. HISTORY OF MICROBIOLOGY

25. https://www.scientistcindy.com/history-of-microbiology.html