This document summarizes the characteristics of eubacteria. Eubacteria are single-celled prokaryotic microorganisms that are enclosed by a cell wall made of peptidoglycans. They lack membrane-bound organelles and reproduce through binary fission. The document further describes the key characteristics of five major phyla of eubacteria: Chlamydias, Cyanobacteria, Gram-positive bacteria, Proteobacteria, and Spirochetes. Examples of common eubacteria, such as Escherichia coli and Streptococcus pneumoniae, are also provided.

1. Mrs. Praveen Garg
VITS College, Satna

2. INTRODUCTION
• Eubacteria, or “true” bacteria, are single-celled
prokaryotic microorganisms.
• They have a range of characteristics and are found in
various conditions throughout all parts of the world.
• All types of bacteria fall under this title, except
for archaebacteria.
• There are three domains of life: Archaea, Bacteria,
and Eukarya.
• Various groups exist as parasites and are responsible
for animal and plant diseases.
• Some are free-living with some being beneficial to
man.

3. Characteristics of Eubacteria
• Eubacteria, or microorganisms lacking a defined
membrane nucleus.
• All are enclosed by a cellular wall, which is made up of
peptidoglycans in a cross-linked chain pattern.
• Unlike eukaryotes, bacteria have cholesterol present in
the membrane to enhance permeability properties of the
membrane.
• Bacteria also have a plasma membrane within
the cell wall.
• Some bacteria may have a flagella, or a projection
composed of protein filaments, that is used for
movement.
• Other bacteria may have pili, which are small projections
all over the outside of the cell, and are used for sticking
to surfaces and transferring DNA.

4. • Cytoplasm is composed of mainly water (70%), but has a
gel-like consistency.
• Bacteria do not have membrane-bound organelles.
• Ribosomes, are made up of RNA and protein used
for protein synthesis. Free floating within the cytoplasm.
• Bacteria can asexually reproduce through binary
fission or budding. Binary fission is when two equal
progeny cells are produced.
• During times of extreme conditions, such as starvation,
eubacteria have the ability to become endospores.
• Plasmids are also found within bacteria separate from
the bacteria’s circular DNA. Also referred to as
“replicons”, plasmids are autonomous replicating DNA
molecules.

5. Types of Eubacteria
 Eubacteria are typically classified into five different
phylums:
Chlamydias,
Cyanobacteria(Blue-green algae),
Gram-positive bacteria,
Proteobacteria,
Spirochetes.

6. SpirochetesProteobacteriaCyanobacteria
Gram positive bacteria

7. Chlamydias
 Chlamydias is a group of organisms belonging to the
family Chlamydiaceae.
 Chlamydias are obligate intracellular parasitic bacteria.
 Chlamydias species are grouped as gram-negative,
their peptidoglycan is not easily detectable.
 They are immotile and are dimorphic in nature.
Chlamydias

8. Gram-positive Bacteria
• A majority of Eubacteria are Gram-positive.
• These group are capable of photosynthesis (photosynthetic
Eubacteria), a majority are chemoheterotrophs and thus
obtain nutrients from their surroundings.
• Being Gram-positive bacteria, these species retain the
primary colour with stain.
• They contain a thick peptidoglycan layer compared to
Gram-negative species.
• Gram-positive bacteria can be found in different types of
aquatic and terrestrial environments.
• Various species (e.g. Mycoplasmas and Actinomycetes) have
been shown to form endospores.
• Many species are parasitic and capable of causing diseases
in animals.
• Actinomycetes produce beneficial compound as antibiotics.

9. Cyanobacteria
• Also known as blue-green algae.
• Cyanobacteria is a class of Eubacteria consisting of
photosynthetic microbes.
• Commonly referred to as photosynthetic prokaryotes.
• These prokaryotes are ubiquitous in nature and can be
found in such environments as ponds, rivers, lakes,
desert soil, and hot springs.
• In these environments, some species are free-living
(capable of photosynthesis) or may form symbiotic
relationships with fungi to form lichens.
• Cyanobacteria include a thick and gelatinous cell wall;
gliding among motile species and diverse morphological
characteristics

10. Proteobacteria
• Proteobacteria represent the largest and most diverse
group among prokaryotes.
• It includes various parasitic bacteria as well a free living
bacteria, involved in nitrogen fixation.
• It include Gram- negative, that can not be stain with
dye and Gram-positive, that can be stained by the dye.
• Based on metabolism, the division is also divided into
three main subgroups that include:
 Purple bacteria (photoautotroph and photoheterotroph
that contain chlorophylls),
 Chemoautotrophic (consisting of free-living and
symbiotic members),
 Chemoheterotrophic (also known as enteric bacteria).
•

11. Spirochetes
• Spirochetes are long, thin, spiral shaped bacteria.
• They are gram- negative bacteria.
• They are known to cause sexual disease.
• They are distinct from the other types of bacteria due to
their helical shape and movement.
• Movement is made possible by the presence of an
internal flagellar filament.
• In nature, Spirochetes can be found in water bodies,
decaying organic matter, animals, plants and soil, etc.
• These group consists of both free-living and pathogenic
organisms that have been shown to cause diseases in
human beings and animals

12. Examples of Eubacteria
Escherichia coli:
 Belongs to the
Eubacteria domain.
 It is classified into the
Proteobacteria phylum.
 It is rod-shaped and Gram-
negative.
 E. coli is commonly found in
the gut of many different types
of warm-blooded hosts,
including humans.
 Most strains are harmless,
but some can cause food
poisoning and other illnesses.

13. Streptococcus pneumoniae:
 It is another common
eubacteria.
 It belongs to the Firmicutes
phylum.
 It is cocci shape, and it is
Gram-positive.
 S. pneumoniae can be found
on healthy hosts in the
respiratory tract, nasal
cavity, and sinuses.
 The bacteria can become
pathogenic and spread to
other parts of the body,
often causing pneumonia
and meningitis in
immunocompromised hosts.

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