What are the differences between Eubacteria and Archaebacteria?


Eubacteria and Archaebacteria are two major groups of prokaryotic microorganisms that play significant roles in various ecosystems. While they share some similarities, there are several key differences that distinguish them from each other. In this article, we will explore the characteristics, classification, habitats, metabolism, and other important aspects of both Eubacteria and Archaebacteria.


Eubacteria, also known as true bacteria, are the most abundant and diverse group of prokaryotes on Earth. They are found in almost every habitat, ranging from soil and water to the human body. Eubacteria have a cell wall composed of peptidoglycan, a unique molecule that provides structural support and protection.

Classification of Eubacteria

Eubacteria are classified into several phyla based on their morphology, metabolism, and other characteristics. Some of the prominent phyla include:

  • Proteobacteria: This is the largest and most diverse phylum of Eubacteria, containing many well-known groups such as Escherichia coli and Salmonella.
  • Firmicutes: This phylum includes bacteria with low G+C content in their DNA and consists of important groups like Bacillus and Clostridium.
  • Actinobacteria: Actinobacteria are known for their filamentous growth and include many antibiotic-producing bacteria like Streptomyces.
  • Bacteroidetes: These bacteria are often found in the human gut and play a crucial role in digestion and nutrient absorption.

Habitats of Eubacteria

Eubacteria have adapted to a wide range of environments due to their remarkable metabolic diversity. They can be found in soil, water, air, extreme habitats like hot springs and deep-sea hydrothermal vents, as well as in symbiotic relationships with plants and animals.

Metabolism of Eubacteria

Eubacteria exhibit various metabolic pathways, allowing them to utilize a wide range of energy sources. Some common metabolic strategies include:

  • Autotrophy: Autotrophic bacteria can synthesize organic molecules from inorganic compounds, such as carbon dioxide. Examples include cyanobacteria, which perform photosynthesis.
  • Heterotrophy: Heterotrophic bacteria obtain energy by breaking down organic compounds produced by other organisms. Most bacteria fall into this category.
  • Chemoautotrophy: Chemoautotrophic bacteria obtain energy from the oxidation of inorganic molecules, such as sulfur or iron compounds.


Archaebacteria, or Archaea, are a distinct group of prokaryotes that are often referred to as extremophiles due to their ability to thrive in extreme environments. They were initially classified as bacteria, but later studies revealed significant genetic and biochemical differences, leading to their classification as a separate domain.

Classification of Archaebacteria

Archaebacteria are classified into several phyla based on their unique characteristics. Some of the main phyla include:

  • Euryarchaeota: This phylum includes methane-producing archaea, known as methanogens, which are commonly found in anaerobic environments.
  • Crenarchaeota: Crenarchaeota are often found in extreme environments such as hot springs and acidic environments. Some species are also capable of oxidizing ammonia.
  • Thaumarchaeota: Thaumarchaeota are marine archaea that play a vital role in the global nitrogen cycle by oxidizing ammonia to nitrite.

Habitats of Archaebacteria

Archaebacteria can be found in various extreme environments, including:

  • Thermal springs: Some archaea thrive in hot springs with high temperatures and acidic conditions.
  • Hydrothermal vents: Archaea can withstand the high pressure and temperature variations found near deep-sea hydrothermal vents.
  • Saline environments: Certain archaea, known as halophiles, can survive in highly saline environments such as salt flats and salt lakes.

Metabolism of Archaebacteria

Archaebacteria exhibit diverse metabolic pathways, enabling them to survive in extreme conditions. Some examples include:

  • Methanogenesis: Methanogenic archaea produce methane as a byproduct of their metabolism and are often found in anaerobic environments.
  • Halophily: Halophilic archaea have adapted to high salt concentrations and possess specialized mechanisms to maintain osmotic balance.
  • Acidophily: Acidophilic archaea can tolerate extremely low pH levels and are often found in acidic environments like sulfuric springs.


1. Are Eubacteria and Archaebacteria considered prokaryotes?

Yes, both Eubacteria and Archaebacteria are classified as prokaryotes, meaning they lack a nucleus and membrane-bound organelles.

2. What is the main difference between the cell walls of Eubacteria and Archaebacteria?

Eubacteria have cell walls made of peptidoglycan, while Archaebacteria have cell walls made of different materials, such as pseudopeptidoglycan or protein.

3. Can Eubacteria and Archaebacteria cause diseases in humans?

Yes, some species of Eubacteria can cause diseases in humans, such as Streptococcus pneumoniae, which causes pneumonia. Archaebacteria, however, are not known to be pathogenic to humans.

4. Can Archaebacteria survive in normal environmental conditions?

Yes, some species of Archaebacteria can survive in normal environmental conditions, although they are more commonly found in extreme environments.

5. Do Eubacteria and Archaebacteria reproduce sexually?

No, both Eubacteria and Archaebacteria reproduce asexually through processes like binary fission and budding.

6. Are there any commercial applications of Eubacteria and Archaebacteria?

Yes, both groups have several commercial applications. Eubacteria are used in the production of antibiotics, enzymes, and fermented foods. Archaebacteria are used in biotechnology for processes like DNA amplification and wastewater treatment.

7. Can Archaebacteria survive in the presence of oxygen?

While some species of Archaebacteria are strictly anaerobic, others can tolerate or even require the presence of oxygen.

8. Are there any Eubacteria that can perform photosynthesis?

Yes, cyanobacteria, a group of Eubacteria, are capable of performing photosynthesis and are considered primary producers in many ecosystems.

9. Are there any similarities between Eubacteria and Archaebacteria?

Both Eubacteria and Archaebacteria are single-celled organisms that lack a nucleus and membrane-bound organelles. Additionally, they both have circular DNA and reproduce asexually.

10. Can Eubacteria and Archaebacteria form colonies or biofilms?

Yes, both Eubacteria and Archaebacteria can form colonies or biofilms, which are complex communities of microorganisms attached to surfaces.


Eubacteria and Archaebacteria are two distinct groups of prokaryotic microorganisms that exhibit significant differences in their cell wall composition, habitats, metabolism, and classification. While Eubacteria are more diverse and can be found in various environments, Archaebacteria are known for their ability to thrive in extreme conditions. Understanding the characteristics and differences between these two groups is crucial for comprehending the immense microbial diversity on our planet.

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