This document provides an overview of bacteria. It begins by defining bacteria and discussing their discovery. It then covers the characteristics of bacteria, including their size, shape, reproduction methods, and habitats. The document also summarizes methods of classifying bacteria based on morphology, oxygen needs, staining properties, heat tolerance, and pathogenicity. Finally, it outlines the structure of bacteria and discusses both the beneficial and harmful effects of bacteria.
2. Objective
At the end of this presentation, the student will be
able to :
Understand the bacteria
Know about the characteristics of bacteria
Know about the classification of bacteria
Know about the structure of bacteria
Know about the disease cause by bacteria
3. Bacteria
The word bacteria is derived from a Latin and a Greek word
Bakteria meaning “cane”. (Rod)
Bacteria is a micro organism with few micro meter in
length and have wide range of shapes (round, oval, rod and
spiral shapes).
First discover by Antony Van Leeun Hook in 1676, initially
called “Animalcules”
Study about bacteria is know as “Bacteriology”, while study
about the harmful effect of bacteria on human body is
known as “Medical bacteriology”.
4. Bacteria
Bacteria are found everywhere on earth i.e. in soil,
water, air, deep earth crust, radio active waste and
acidic hot spring
A single gram of soil contain 40 million bacteria while
a million bacteria found in an ml of fresh water.
However only few of these are harm full to human
body causes disease
They produce more Oxygen than plants
5. Bacteria
Bacteria are earlier form of life form on earth.
Their fossils are found 2.5 billions years ago
6. Characteristics of Bacteria
Size of bacteria rang between 0.5 to 5 micrometer
They are prokaryotic microbes (have no membrane
bounded Nucleus and mitochondria)
Have a single chromosome as Genetic material
Enclosed in a rigid cell wall made up of peptidoglycane
Some bacteria, along with plasma membrane, contain
an additional membrane called Capsule
7. Characteristics of Bacteria…..
Reproduce by Amitosis (asexual form of reproduction)
Many bacteria form Spores
Some bacteria are Auto tropes while some are hetro
tropes
Most grow best at pH of 6.5 to 7.0
Many act as decomposers recycling nutrients
8. Nutrition Source for bacteria
Saprobes –
feed on dead organic matter
Parasites
feed on a host cell
Photoautotroph
use sunlight to make food
Chemoautotroph
oxidize inorganic matter such as iron or sulfur to
make food
9.
10. Classification of bacteria
Bacteria are classified according to following properties
1. According to Morphology
2. According to Needs for Oxygen
3. According to Staining they retain
4. According to Heat Tolerance
5. According to Pathoginicity
11. According to Morphology
According to morphology (shape), Bacteria are
classified into
Cocci
Those who appear in Round or oval shape
Bacilli
Those who appear in Rod shape
Spirillia
Those who appear in spring spiral or shape
13. Arrangement of Bacteria
Diplococci
Arrange in pairs
Stephylo cocci
Arrange in cluster
Strepto cocci
Chain like arrangement
14.
15.
16. According to Needs for Oxygen
According to their need for oxygen, Bacteria are
classified into
Aerobic
Those who required Oxygen to live
Anaerobic
Those who don’t required Oxygen to live
Facultative Aerobic
Those who can adjust in either presence or absence of
Oxygen
17. According to Staining they retain
According to stain (color) they retain or appear
during the procedure of gram staining, Bacteria are
classified into
Gram Positive
Those who appear blue, purple or violate in color
Gram Negative
Those who appear red or pink in color
19. According to Heat Tolerance
According to temperature on which Bacteria can be
best live, they are classified into
Psychrophilic bacteria
Can survive on extreme cold temperature
Mesophilic bacteria
Can survive on extreme cold temperature
Thermophilc bacteria
Can survive on extreme hot temperature
20. According to Pathoginicity
According to disease causing ability of bacteria, they are
of two types
Pathogenic bacteria
Those who cause disease in human
Non-Pathogenic bacteria
Those who cannot cause disease in humans
28. Bacteria Reproduction
Under optimum conditions bacteria can reproduce
every 20 minutes. (double every 10 to 20 minutes.
Bacteria reproduction is controlled by various factors
including : temperature and food availability.
Their reproduction can be by:
Asexual: Binary fission
Sexual: conjugation
29. Binary Fission
• It involves the
copying of the
DNA and the
splitting into
two new cells.
31. Beneficence of Bacteria
Makes cheese, yogurt, buttermilk and pickles
Produces vitamins in your intestine
Helps in digestion of insoluble fibers
In industry, bacteria are important in sewage
treatment and the breakdown of oil spills, the
recovery of gold, copper and other metals in the
mining sector,
32. Beneficence of Bacteria
Bacteria are also helpful in biotechnology, and the
manufacture of antibiotics and other chemicals.
Many act as decomposers recycling nutrients
Actinomycetes, produce antibiotics such as
streptomycin and nocardicin.
Saprobes help to break down dead organic matter.
33. Harmful effect of Bacteria
Cause disease in body including:
1. TB
2. Pertusis
3. Diphtheria
4. Tetanus
5. Dysentery
6. Typhoid
7. Meningitis, Encephalitis
8. Gonorrhea
9. Pneumonia
10. Syphilis
34. Endospores
Some bacteria are capable to produce spore that
are highly resistant to extreme environmental
condition.
In favorable condition, bacteria re grow again to a
bacteria
35. Toxins
Some bacteria release poisons known as toxins which
cause food poisoning. Some toxins, known as
exotoxins multiply in food. These toxins are not easily
destroyed by cooking and may remain in food once
they have developed.
Other bacteria produce toxins inside the human body
only after the food has been eaten. These are called
endotoxins