1. Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms including eukaryotes such as fungi and protists, and prokaryotes which are bacteria and archaea. Viruses are also studied. 2. Major developments in the history of microbiology include the invention of the compound microscope which allowed the first observations of microbes, and the work of Leeuwenhoek, Hooke, Pasteur, and Tyndall which disproved spontaneous generation and established the germ theory of disease. 3. Microbiology has applications in fields such as medicine, agriculture, food science, ecology, genetics, biochemistry, and immunology.

1. Introduction of Microbiology
Course : B.Sc. Biotechnology, Biochemistry
Sem II
Sub: Basic Microbiology
Unit 1.1

2. Microbiology
• Microbiology
• Greek word : mikros - "small"; bios - "life“ and logia- Science
• Is the study of microorganisms, which are unicellular or cell-
cluster microscopic organisms.
• This includes eukaryotes such as fungi and protists, and
prokaryotes which are bacteria and archaea.
• Viruses, though not strictly classed as living organisms, are also
studied.

3. History of Microbiology
 Lucretius, a Roman philosopher
 Fracastoro, a 16th century physician
• Before they were visibly observed, microbes were suspected
not only to exist, but also to cause disease.
• 1590 - Hans Jansen developed the first useful apparatus with
compound lenses.
• Robert Hooke first observed and described microbes
 Inventor of the 17th century
 Coined the term “cells” to describe the “little boxes”
 He observed in examining cork slices with a compound
microscope
 In 1665, published the book Micrographia documenting
his various observations
 In 1678, he was asked to confirm van Leeuwenhoek’s
observations

4. • Leeuwenhoek
 Developed single lens microscopes
 1673 to 1676 - publishes his discovery of
“animalcules”
• Bacteria
• Protozoa
• “Vinegar eels”

5. • From before the time of Aristotle (384-322 B.C.), people believed that life could arise
from non-living matter, i.e., spontaneous generation.
• “Evidence” includes:
 Mice from grain
 Beetles from dust
 Worms and frogs from mud
 Maggots from rotting meat
• In the late 1600s, Francesco Redi challenged this view through a series of experiments
involving rotting meat.
• Redi’s experiments, and those by others, refuted the spontaneous generation theory
for larger organisms.
• These experiments did not, however, dispel speculation that the theory still held true
for microorganisms.
• Proponents cited evidence of microbial growth in boiled extracts of hay or meat.

6. • By the late 1800s, Pasteur and Tyndall conclusively disproved
the theory of spontaneous generation
• Louis Pasteur
• Father of Microbiology
• Contributions include:
• Wine fermentation
• Microbial diseases of grapes and silkworms
• “Pasteurization”
• Rabies vaccine
• In 1861, Pasteur provided definitive proof against
spontaneous generation using swan necked flasks.

7. • John Tyndall
 English physicist - first scientist to study greenhouse
gases and climate change
 Demonstrated the existence of heat-resistant
bacteria, thereby extending Pasteur’s findings

8. Giants of the early days of microbiology and their major contributions

9. Scope of Microbiology
• Microbiology has an impact on
 Medicine
 Agriculture
 Food science
 Ecology
 Genetics
 Biochemistry
 Immunology

10. Production of antibiotics
• Most of the antibiotics are produced from
microorganisms.
• Industrial microbiology concerns itself with the
isolation of antibiotic producing microorganisms from
natural environments such as soil or water.
• Many antibiotics are isolated from natural
microorganisms by the process of fermentation.
Antibiotics Microbial scourse
Penicilin Penicillium species
Streptomycin Streptomyces griseus
Chloramphenicol Streptomyces venezuelae
Tetracycline Streptomyces rimosus
Neomycin Streptomyces fradiae

11. Production of human hormones
• Bacteria have been inserted with human genes that
control the production of insulin, Human growth
hormone and interferon.
• The bacteria can produce these in mass quantities that
human cannot.
1. Human insulin
Amongst the earliest uses of biotechnology in
pharmaceutical manufacturing is the use of
recombinant DNA technology to modify Escherichia
coli bacteria to produce human insulin.
Genentech researchers produced artificial genes for
each of the two protein chains that comprise the
insulin molecule.

12. 2. Production of vitamin
Bacteria like E. Coli present in human colon are involved in
synthesis of vitamins like vitamin b12, folic acid, biotin and K, which may be
used by the host. Such bacteria are often used for commercial preparation
of vitamins like riboflavin.
3. Production of Antiseptic
• Antiseptics are antimicrobial substances that are applied to living
tissue/skin to reduce the possibility of infection, sepsis or putrefaction.
• Some antiseptics are true germicides, capable of destroying microbes
(bactericidal) whilst others are bacteriostatic and only prevent or inhibit
their growth.
• Antibacterial are antiseptics that only act against bacteria.
• Microbicides which kill virus particles are called viricides.
• Some common examples of antiseptics are alcohols, Quaternary
ammonium compounds, Boric acid, Chlorhexidine Gluconate, Hydrogen
peroxide, Iodine, phenol etc.

13. Medical Microbiology
• Medical Microbiology helps in the diagnostic protocol for
identification of causative agents of various human
aliments, alimentes & subsepuents preventive measures.
• Genetic engineering
• Microorganisms can now be genetically engineered to
manufacture large amounts of human hormones.
• Microorganisms play a central role in recombinant
DNA technology and genetic engineering. Important
tools of biotechnology are microbial cells, microbial
genes, and microbial enzymes.

14. Pharmaceutical Microbiology
• Pharmaceutical Microbiology – is the part of industrial
microbiology that is responsible for creating medications.
• The making of life-saving drugs, antibiotics e.g.
Penicillin’s, ampicillin, chloramphenicol, ciprofloxacin,
tetracyclines, and streptomycin belong to the sector of
pharmaceutical microbiology.
• There are many useful products made by microbes.
Industrial microbiology
• Industrial microbiology making of ethanol, acetic acid
lactic acid, citric acid, glucose, syrup, high-fructose
syrup.

15. Waste-Treatment Microbiology
• Waste-Treatment Microbiology includes treatment of
domestic and industrial effluents or wastes by
lowering the COD.
• Without microbes we would have an over abundance
of dead things.
• Microbes are also used to clean up oil, toxic waste,
and dynamite and sewage treatment.

16. Immunology
• Immunology is the branch of medicine and biology concerned
with immunity.
• Immunology studies the system of body defenses that protects
against infection.
• It includes serology, a discipline that looks for the products of
immune eactions in the blood and tissues and aids in diagnosis
of infectious diseases by that means, and allergy, the study of
hypersensitive responses to ordinary, harmless materials.

17. Food Microbiology
• that microorganisms were responsible for the chemical changes
that take place in foods and beverages.
• Microorganisms play an important role in
• Food preservation
• Food spoilage
• Food poisoning
• Food fermentation
• Food hygine
• Food-born disease
• Food quality control

18. • 1.5 million tons of baker’s yeast (Saccharomyces
cerevisiae) are produced worldwide every year.
• Cheese production also has ancient origins.
• Beverage Microbiology making of beer, sandy, wine,
and a variety of alcoholic beverage e.g. whisky, brandy,
rum, gin, vodka, etc.
Fermented Food Substrate Microorganisms
Idli Rice and blackgram Leuconostoc mesenteroids,
Streptococcus faecalls
Yoghurt Milk Streptococcus thermophillus,
Lactobacillus bulgaricus
Kefir Milk Lactobacillus and Yeast
Cheese Milk Penicillium sp, Lactobacillus sp

19. Fields of Microbiology

20. Phycology
• Phycology (from Greek word, phykos, "seaweed"; and -logia) is the
scientific study of algae.
• Phycology/ Agologist is a branch of life science and often is
regarded as a subdiscipline of botany.
• Algae are important plants as primary producers in aquatic
ecosystems.
• Most algae are eukaryotic, photosynthetic organisms that live in a
wet environment.
• They are distinguished from the higher plants by a lack of true
roots, stems or leaves. They do not flower.
• Many species are single-celled and microscopic (including
phytoplankton and other microalgae); many others are multicellular
to one degree or another, some of these growing to large size (for
example, seaweeds such as kelp and Sargassum).
• Phycology includes the study of prokaryotic forms known as blue-
green algae or cyanobacteria.
• A number of microscopic algae also occur as symbionts in lichens.

21. Mycology
• Mycology is the branch of biology concerned with the study of
fungi, including their genetic and biochemical properties, their
taxonomy and their use to humans as a source for tinder,
medicine (e.g., penicillin), food (e.g., beer, wine, cheese, edible
mushrooms), and entheogens, as well as their dangers, such as
poisoning or infection.
• From mycology arose the field of phytopathology, the study of
plant diseases, and the two disciplines remain closely related
because the vast majority of "plant" pathogens are fungi.
• Historically, mycology was a branch of botany because,
although fungi are evolutionarily more closely related to
animals than to plants, this was not recognized until a few
decades ago.

22. Virology
• Virology is the study of viruses – submicroscopic, parasitic
particles of genetic material contained in a protein coat – and
virus-like agents.
• It focuses on the following aspects of viruses: their structure,
classification and evolution, their ways to infect and exploit host
cells for reproduction, their interaction with host organism
physiology and immunity, the diseases they cause, the techniques
to isolate and culture them, and their use in research and
therapy.
• Virology is considered to be a subfield of microbiology or of
medicine.

23. Bacteriology
• Bacteriology is the branch of biology that deals with the study of
minute organisms called bacteria (singular bacterium).
• Bacteria: a single-celled, often parasitic microorganism without
distinct nuclei or organized cell structures. Various species are
responsible for decay, fermentation, nitrogen fixation, and many
plant and animal diseases.
• They are:
 Prokaryotes
 Single-celled organisms
 Size: microscopic.
 E.g. E. coli is 1.3 um wide x 1.0 um long.
6250 E. coli to make 1 inch

24. Medical microbiology
• This branch deals with the pathogenic microbes, their life
cycle, physiology, genetics, reproduction etc., many of the
microbes also provide remedies for microbial diseases. All
these aspects are studied in this branch.
• Some of the diseases like tuberculosis, leprosy, typhoid etc are
caused by microbes and cure for them is provided by other
microbes in the form of antibiotics.

25. Agricultural microbiology
• It is dealing with the various aspects of agriculture.
• In this branch the role of microbes in agriculture is studied
from the point of view of both harm and usefulness.
• Many microbes - fungi, bacteria and viruses cause a number
of plant diseases.
• From the point of view of benefit - N2 fixing activity, use of
microbes as biofertilizers and several other aspects are
studied.

26. Industrial microbiology
• The role of microbes in Industrial Production is studied.
• Many microbes produce industrial alcohols, and acids as apart
of their metabolism.
• The study of fermentation by microbes has contributed a
great lot to alcohol manufacturing. Breweries have greatly
benefited by understanding the role of specific microbes in
fermentation.

27. Food and Dairy microbiology
• Various aspects such as food processing, food preservation,
canning, Pasteurization of milk, study of food borne microbial
diseases and their control is studied.
• Micro-flora of fruits and vegetables are also studied.
• It deals with the fermentations and fermented products like
yogurt, cheese, sauerkraut, sausage, baker’s yeast, soy sauce,
beer, wine, etc.
• These microbiologists involve in prevention of deterioration and
spoilage of the food products and have a continuous hygiene
checks on the food products to prevent any food poisonings.
• Application of enzymes in food and dairy industry is studied.

28. Aquatic microbiology
• Microbiological examination of water, water purification,
biological degradation of waste are studied in this branch.
Aero microbiology
• Dispersal of disease causing microbes through air microbial
population in air, their quality and quantity in air comes under
the perview of this branch.

29. Environmental microbiology
• This is one of the most important branches of micro biology.
• It involves in the study of ecological study which includes air,
water, food and environment as such.
• These microbiologists check the factory wastes which can cause
pollution of the air or water thus increasing the rate of poisoning
or diseases in the environment.
• The role of microbes in maintaining the quality of the
environment is studied here.
• Microbial influence in degradation and decay of natural waste,
their role in biogeochemical cycles are all studied.
• Some of the recent researches have shown that certain bacteria
can help in cleaning the oil spill and this gives added significance
to the study of environmental microbiology.

30. Geochemical microbiology
• Role of microbes in coal, gas and mineral formation,
prospecting for coal, oil and gas and recovery of minerals from
low grade ores using microbes is included here.
• This is the most significant branch which may even change the
course of life as we know today. Microbes are used as gene
carriers to deliver specific genes to function in a different
environment.
• New, genetically engineered microbes can produce drugs
(human insulin) or in agriculture N2 fixing ability may be
transferred to all the plants. The Potentialities of bio-
technology are immense.
Biotechnology

31. Immunology
• Studied in this branch are the immune responses in
organisms.
• How toxins are produced,
• How the antigens influence the formation of antibodies,
• How protective vaccination helps in combating the diseases,
• How immune system collapses (as in AIDS) are some of the
questions for which immunology as a branch of microbiology
is trying to find out answers.

32. Medical Microbiology
• Involves in identifying, treatment or prevention of some
diseases caused by bacteria, virus, and fungi.
• The medical microbiologists research on different diseases,
their causes, development and pathogenesis.
• Every human needs good, purified water for survival.
• These microbiologists ensure and monitor the quality of the
water supplied to the domestic areas.

33. Bacteriology
• It dealing with the Study of bacteria.
• This subdivision of microbiology involves the identification,
classification, and characterization of bacterial species.

34. Major groups of Microorganisms

35. Introduction
• Microorganisms are named based on their
particular physiological and nutritional
characteristics.
• Based on Temperature:
1. Psychrophile
2. Psycrotroph
3. Mesophile
4. Thermophile
5. Hypothermophile

36. Based on Temperature
Tyepes of Microbe
Optimum growth
Teperature
Growth Temp Range
Psychrophile 15 oC 0-20 oC
Psycrotroph 5 oC 0-25 oC
Mesophile 37 oC 10-45 oC
Thermophile 50 oC -
Hypothermophile 80 oC -

37. Based on pH requirements
pH
• The pH scale is a measure of hydrogen ion (H+) concentration. Low pH corresponds
with high concentrations of hydrogen ion, neutral pH with equal numbers of hydrogen
and hydroxyl ions (OH-), and high pHs correspond to low concentrations of hydrogen
ion
Optimum pH
• Optimum pH is that pH at which a given organism grows best. The range over which
• most organisms can grow tends to vary over no more than a single pH unit in either
• direction (e.g., from pH 6 to pH 8 for an organism whose pH optimum is pH 7)
Acidophiles
• Organisms whose optimum pH is relatively to highly acidic, which means growing best
in acidic pH
Neutrophiles
• Organisms whose optimum pH ranges about pH 7, plus or minus approximately 1.5 pH
units
Alkaphiles
• Organisms whose optimum pH is relatively to highly basic, which grow best in high pH

38. Based on oxygen requirements
• Organisms differ in their requirements of molecular oxygen (i.e., O2) as
well as other atmospheric gasses (e.g., carbon dioxide). Categories of
organisms as per their oxygen requirements include:
Obligate aerobe
• Organisms that are unable to grow in the absence of oxygen or they
require oxygen for their growth. Some times this group of organism
may be called strict aerobes as they can not grow without oxygen.
Facultative aerobe
• Organisms that can grow in the absence normal level of oxygen that is
other wise required.
Microaerophile
• These are organisms that grow best when small amounts of oxygen are
present. That is, less than atmospheric concentrations, but more than
those concentrations tolerable by obligate anaerobes

39. Obligate anaerobe
• Organisms that are strict anaerobe and require complete
absence of oxygen for their growth, which mean they
cannot grow in the presence of oxygen.
Facultative anaerobe/Facultative aerobe
• Facultative anaerobes can grow either in presence or
absence of oxygen. These organisms tend to exist in
environments in which oxygen concentrations are
uncertain.
Aerotolerant anaerobe
• These are organisms that are able to grow in the presence
of oxygen though they do not require it for their growth.
Based on oxygen requirements

40. Capnophiles
• These are organisms whose optimum growth requires relatively high concentrations
of carbon dioxide
Osmotic pressure
• The concentration of dissolved substances in the environment can impact on the
growth and survival of bacterial cells.
• Osmophilic organisms are microorganisms adapted to environments with high
osmotic pressures, such as high sugar concentrations.
Plasmolysis
• Environments containing large concentrations of dissolved substances draw water out
of cells, causing shrinkage of the cytoplasm volume, a phenomenon termed
plasmolysis.
• Plasmolysis interferes with growth and this is why highly osmotic environments
prevent bacterial growth (e.g., brine, the high sugar concentrations in jellies and jams,
salting of meats)
Halophiles
• Organisms that require high concentrations of dissolved salts to grow are termed
halophiles.
• Depending on organism, the salt concentrations required range from those of
seawater on up to those of brine.

41. References
Books:
1. Biology of microorganisms By M. T. Madigan, J. M. Martinko, D.
A. Stahl and D. P. Clark
Websites:
1. http://en.wikipedia.org/wiki/Virology
2. http://en.wikipedia.org/wiki/Mycology
3. http://en.wikipedia.org/wiki/Phycology
4. http://www.gitam.edu/eresource/environmental/em_maruthi/i
ntroduction.htm#4