This document provides an introduction to bacteria, including their characteristics, classification, reproduction, and importance. It discusses the early discoveries of bacteria using microscopes from the 16th century onwards. The document outlines different types of bacteria based on their nutrition, respiration, staining properties, and shape. Methods of bacterial reproduction such as binary fission, budding, endospores, and conjugation are described. The document also discusses bacterial infection of host plants and Koch's postulates for identifying pathogenic bacteria. Several important bacterial diseases affecting crops are listed and the significance of bacteria in areas like food, agriculture, industry, and medicine is highlighted.

1. Mr. Dev Kumar Arya
(Lecturer)
Department of Genetics and Plant Breeding
O.P. Agriculture College Budhwal, Behror, Alwar (Raj..),India
Affiliated to Sri Karan Narendra Agriculture University,
Jobner,(Rajsthan),India
Email:devkumararya59@gmail.com
INTRODUCTION OF BACTERIA

2. Outline
 Introduction of Bacteria
Characteristics
Some important history
Classification of Bacteria
Reproduction in Bacteria
Infection on host Plant by Bacteria
Koch Postulates (Given by Robert Koch)
Some Important Bacterial diseases
Importance of Bacteria

3. Introduction
“Bacteria is a microscopic,prokaryotic,living microorganism. Which
reproduce by binary and can cause diseases.” Kingdom-
Monera,Phylum-Protobacteria,Class-clostridia,Oder-
Clostridiale,Family-Clastridiaceae,Genus-Clastridium.

4. History
Inverted the first compound microscope by Janssen,Z in 1590.
 In 1626 Discovered spontaneous generation by F.Redi
In 1676 Discovered bacteria using a single-lens microscope of his own design. by
A.Leeuwenhoek
In 1856 pasturization technique gave by L.Pasture
In 1872 first to use solid medium by G. Schroeder
In 1884 Gram staining technique given by H.C.Gram
 In 1890 koch postulates gave by Robert.Koch
In 1933-38 electron microscope Developed by E.Ruska and Von Borries
In 1945 Novel prize for discovery of penicillin by A.Flaming
In 1946 Conjugation discovered by J. Lederberg and E.Tatum

5. Characteristics
 It is a simple Prokaryotic and primitive organism.
 It is a unicellular,microscopic living microorganism.
 In bacteria has not true nucleus because in bacterial cell has not nuclear
membrane and nucleolus.
 The reproduction in bacteria is mainly by cell division and binary fission. In
some cases few bacteria also reproduce by budding.
 Bacterial cell wall composed by chitin.
 Mainlly shape of bacteria (spherical,spirilla,bacilli).
 Bacterial cells have many plasmids which is small circle of DNA.
 Plasmids are used to exchange DNA between the bacterial cells.
 Flagella is a rigid rotating tail,which helps the cell to move in clockwise and
anticlockwise, forward and also helps the cell to spin.
 Cytoplasm helps in cellular growth, metabolism and replication.
 An average bacillus is 0.5-1.0 µm wide by 1.0-4.0 µm long. Spirals range in
size from 1 µm to over 100 µm in length.
 The study of Bacteria is known as Bacteriology.

6. Classification
Nutrient based
(A)Autotrophic-Autotrophs are those bacteria,which need only inorganic
nutrients/compounds for example-chlorobacterium,chlorobium,Bacillus.
Phototrophs-These use light as the source of energy.
Chemotrophs-These use chemical source of energy(dark oxidation-reduction reaction)
Lithotrophs-Lithotrophs are bacteria which use reduced inorganic compounds as the
electron donor (H-donor) in anaerobic or aerobic respiration.
(B)Heterotrophic-Heterotrophs require organic nutrients.for example-
saprophytic,symbiotic ,parasitic bacteria.
Parasitic- These bacteria obtain their food from the tissues of living organisms, the
hosts. They may be harmless or may cause serious diseases.
Saprophytic- These bacteria obtain their food from the dead organic substances such
as leaves, fruits, vegetables, meat, animal humus residuce etc.
Symbiotic-These bacteria live in close association with other organisms as symbionts.
They are beneficial to the organisms. The common examples are the nitrogen-fixing
bacteria, e.g.azotobacter, Rhizobium, Clostridium etc

7. Respiration based
(a)Aerobic bacteria-
Obligate aerobes: These are strict aerobes that mean they always require oxygen for
their survival. They are not able to withstand anaerobic conditions.
Facultative aerobes: These are bacteria which normally respire anaerobic but can
move to aerobic conditions, if the situation demands.
(b)Anaerobic bacteria-
Obligate anaerobes: These are again strict types of anaerobes. They can survive only if
oxygen is deficient but are not able to withstand if oxygen is present.
Facultative anaerobes: These are not of strict types. They normally respire aerobically
but can shift.
Gram staining based
Gram positive bacteria: Stain dark purple due to retaining the primary dye called
Crystal Violet in the cell wall.
Example: Staphylococcus aureus
Gram negative bacteria: Stain red or pink due to retaining the counter staining dye
called Safranin.
Example: Escherichia coli

8. Diplococci: Cells divide in one
plane and remain attached in
pairs.
Streptococci: cells divide in one
plane and remain attached to
form chains.
Tetracocci: : Cells divide in two
planes and form group of four
cells.
Staphylococci: cells divide in
three planes, in an irregular
pattern, producing bunches of
cocci.
Shape based

9. Vegetative reproduction-It is process
In which produce organism by any
vegetative parts of an organism.
Binary fission-In this case One
parental cell divide in to two
duaghter cells which have nucleus.
Budding-It is a process in
Which the production of buds from
parent.
Reproduction in Bacteria

10. Asexual reproduction-It is a process in which new individual arise without
fertilization from unfertilized gametes.
There are divide into two parts.
Endospores-Endospore formation is
usually triggered by a lack of nutrients,
and usually occurs in gram-positive
bacteria.
Conidia-Only true spores, reproductive
structures produced for dissemination and
multiplication of the species, are the
Conidia.

11. Conjugation-It is a
process in which the
transfer of genetic
material from one cell
to another cell
through cell contact
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• plasmid copies itself
• passes through pili
(cytoplasmic bridge) into
recipient cell
• cells separate with both
cells containing the
plasmid
plasmid
donor recipient
cell (+) cell ( - )
pili
Sexual reproduction

12. Transduction-It is the process by
which foreign DNA is introduced
into a cell by a virus . An example
is the viral transfer of DNA from
one bacteria to another.
Transformation-Some
bacteria have another
method transferring DNA and
producing recombinants that
does not require conjugation

13. Infection on Host plant

14. Inoculation-Transfer of a pathogen to the host.
Inocubation-It is a process in which To bring a pathogen into contact
with a host.
Penetration-The initial invasion of a host by a pathogen.
Infection-The estabilishment of a parasite within a host plant.
Recognition-Specific receptor molecules or structures on the host plant
that can be recongnized by the pathogen.
Invasion-The spread of a pathogen into the host.
Colonisation-Colonization is a process by which a central system of
power dominates the surrounding land and its components.

15. Heinrich
Hermann
Robert Koch
(11 December
1843 – 27 May
1910) was a
German
physician
who
developed
Koch's
postulates

16. Koch's
(A)The microorganism or other
pathogen must be present in all cases
of the disease
(B)The pathogen can be isolated from
the diseased host and grown in pure
culture
(C)The pathogen from the pure culture
must cause the disease when
inoculated into a healthy, susceptible
plant.
(D)The pathogen must be reisolated
from the new host and shown to be
the same as the originally inoculated
pathogen. This step is given by
(E.F.Smith)

17. Some important Bacterial Diseases
Bacterial Blight of cotton -Xanthomonas compestris
Baterial Blight of mungbean –Xanthomonas compestris
pv.vignaeradiatae
Bacterial Blight of rice- Xanthomonas oryzae
Citrus Canker of citrus- Xanthomonas citri
Red scripte of sugarcane- Xanthomonas rubrriliance
Bcterial spot of stone fruits- Xanthomonas arboricola
Leaf spot of tomato,chilli- Xanthomonas vesicatoria
Moko disease of banana- Ralstonia solanacearum
Black leg of maize- Erwini chrysanthemii pv.zeae
Bacterial blight of soyabean -Pseudomonas
savastonai glycinea
Soft rot of potato - Erwinia carotovara pv.caroto.

18. Importance of Bacteria
In food material
In agriculture
In industry
In public health
For cleanliness
For alchohol production
For chemical /medicine

19. Any query ?
Thank you for listening