Archaebacteria

Archaebacteria is a group of microorganisms that are distinct from bacteria and eukaryotes. They thrive in extreme environments, such as hot springs, salt lakes, and deep-sea hydrothermal vents. Studying the Archaebacteria characteristics and Archaebacteria classification helps in their unique adaptations to extreme environments and their evolutionary relationships with other life forms.

In this article, we will cover Archaebacteria in detail.

Kingdom Monera is the first kingdom in the 5-kingdom classification system. It includes prokaryotic organisms, lacks a nucleus, and most are composed of single-celled organisms. In 1866, Ernst Haeckel was the one who proposed the taxon Monera. There are two divisions of Monera, i.e., Archaebacteria and eubacteria.

This kingdom includes all types of bacteria. The first ever bacteria were discovered by Antonie van Leeuwenhoek in 1675. The oldest known microorganisms which are known on the earth are put under this kingdom. These species lack nuclei and due to this their genetic material is also not enclosed, but it is loose inside the cell of these species. Monera is classified into three subkingdoms which are:

• Archaebacteria
• Eubacteria
• Cyanobacteria

Let’s discuss Archaebacteria in detail.

Archaebacteria, now known as Archaea, are single-celled prokaryotes without a nucleus. Unlike the other two domains, Eubacteria and Cyanobacteria, Archaea possess unique properties that distinguish them from other subkingdoms. Many Archaea cannot be isolated in labs, making their classification challenging and primarily based on gene sequences from environmental samples.

While Archaea and bacteria share similar sizes and shapes, Archaea exhibit diverse forms, such as the flat, square cells of Haloquadratum walsbyi. Additionally, the enzymes involved in Archaea’s translation and transcription processes are more closely related to those of eukaryotes, and some of their metabolic activities also resemble those of eukaryotes.

Some of the important characteristics of Archaebacteria are given below:

• Archaebacteria Cell Walls: Their cell walls do not contain peptidoglycan, unlike bacteria. Instead, they have unique molecules like pseudopeptidoglycan.
• Extreme Environments: Archaebacteria can live in extreme conditions such as hot springs, salty lakes, and deep-sea hydrothermal vents.
• Diverse Metabolism: They can use a variety of energy sources, including hydrogen gas, carbon dioxide, sulfur, and even sunlight (for photosynthetic species).
• Methanogens: Some archaebacteria produce methane gas as a byproduct of their metabolism. These are called methanogens and are often found in anaerobic environments like swamps and the guts of ruminant animals.
• No True Nucleus: Like bacteria, archaebacteria are prokaryotes, meaning they lack a true nucleus. Their genetic material is not enclosed in a nuclear membrane.
• Different Membrane Lipids: Their cell membranes have lipids that are different from those found in bacteria and eukaryotes. These lipids help them survive extreme conditions.
• Genetic Similarities to Eukaryotes: Some of their genetic processes and enzymes are more similar to those found in eukaryotes than those in bacteria, suggesting a closer evolutionary relationship.
• Reproduction: Archaebacteria reproduce asexually through binary fission, budding, or fragmentation.
• Resistance to Antibiotics: Many archaebacteria are resistant to antibiotics that affect bacteria, due to differences in their ribosomes and enzymes.

On the basis of phylogenetic relationships, Archaebacteria is divided into 5 divisions which are as follows:

Crenarchaeota

The bacteria which can survive in a wide range of habitats is known as crenarchaeota. They can also survive in extremely high temperatures. To survive extremely high temperatures, there is a need for many special proteins which are present in these bacteria. These bacteria also survive in highly acidic environments.

The usual habitat of these bacteria is hot springs, deep-sea vents, and places where there is super-heated water All the hyperthermophiles, thermoacidophiles, and thermophiles are included in this category of Archaebacteria.

Euryarchaeota

This category is specialized in surviving extreme alkaline conditions. The only bacteria to perform cellular respiration using carbon as an electron receptor is Euryarchaeota. There are only very few bacteria that can produce methane, and those bacteria fall under this category of Archaebacteria. Methanogens and halophiles are included under euryarchaeota.

Korarchaeota

The common factors of crenarchaeota, euryarchaeota, and korarchaeota are their genes. Common ancestors are present in all three categories. Hyperthermophiles are included under this subcategory as they have the ability to survive extra extremely high temperatures and these bacteria are believed to be the oldest existing bacteria on the earth.

Thaumarchaeota

The bacteria which have the ability to oxidize ammonia are kept under this category.

Nanoarchaeota

Ignicoccus is the genus to which these bacteria belong. These are the obligate symbiont of archaea.

Archaebacteria thrives in diverse habitats.

• Archaebacteria thrive in extreme environments such as hot springs, acidic lakes, and deep-sea hydrothermal vents.
• They can withstand high temperatures, acidity, and salinity, making them well-suited for habitats that would be inhospitable to most other organisms.
• Some Archaebacteria species are found in more moderate environments like soils, marshes, and the digestive tracts of animals.
• Their ability to colonize such diverse habitats showcases their adaptability and resilience in a wide range of ecological niches.

Archaebacteria reproduce asexually through methods such as binary fission, budding, or fragmentation, where one parent cell divides to produce genetically identical daughter cells. Some species also exchange genetic material through horizontal gene transfer methods like conjugation, transformation, or transduction.

The importance of Archaebacteria are:

• Extreme Environment Adaptation: Archaebacteria thrive in extreme environments like hot springs, acidic lakes, and deep-sea hydrothermal vents, contributing to our understanding of life’s adaptability.
• Biotechnology Applications: Some archaebacteria produce enzymes and proteins with unique properties, valuable for industrial processes like DNA replication, PCR (polymerase chain reaction), and protein engineering.
• Bioremediation: Certain species of archaebacteria can degrade pollutants and toxins, offering potential solutions for environmental cleanup.
• Role in Symbiosis: Archaebacteria engage in symbiotic relationships with other organisms, such as methanogens in the gut of ruminant animals helping in digestion.
• Evolutionary Insights: Studying archaebacteria provides insights into early life forms and evolutionary relationships, shedding light on the origins of cellular life on Earth.

Some of the examples of Archaebacteria are:

• Lokiarchaeota: Found in deep-sea vents at “Loki’s Castle,” these thermophilic bacteria have a unique genome containing genes involved in phagocytosis and maintaining cell shape, suggesting a connection to the origin of eukaryotes.
• Methanobrevibacter Smithii: Located in the human gut, it produces methane and helps in breaking down complex sugars, playing a crucial role in energy extraction from food and potentially providing protection against colon cancer.
• Sulfolobus: Thriving in acidic hot springs, Sulfolobus species are known for their ability to withstand extreme temperatures and acidic conditions, contributing to biotechnology research and enzyme production.
• Methanosarcinales: These methanogenic archaea are found in anaerobic environments such as marshes, sewage sludge, and the digestive tracts of animals, playing a significant role in methane production and the carbon cycle.

The Kingdom Monera including prokaryotic organisms, stands as the first classification in the five-kingdom system, with Archaebacteria and eubacteria as its main divisions. Archaebacteria, also known as Archaea, are single-celled prokaryotes devoid of a nucleus, exhibiting unique genetic and biochemical characteristics. Understanding their distinct characteristics sheds light on early life forms and evolutionary relationships, offering insights into the origins of cellular life on Earth. These microorganisms thrive in extreme environments, contributing to biotechnology, symbiotic relationships, and environmental cleanup, showcasing their significance in various scientific domains.

Also Read:

• Gram Staining
• Cell Envelope
• Difference Between Archaea and Bacteria
• Characteristics and Classification of Monera
• Facts About Bacteria
• Bacteria Reproduction – Sexual and Asexual

What are Archaebacteria Class 11?

Archaebacteria are single-celled microorganisms that belong to the domain Archaea and exhibit characteristics different from both bacteria and eukaryotes.

What is the Simple Definition of Archaebacteria?

Archaebacteria, or archaea, are ancient single-celled microorganisms with unique genetic and biochemical properties.

What are 6 Facts about Archaebacteria?

Some facts about archaebacteria are: Archaebacteria thrive in extreme environments, contribute to biotechnology, helps in digestion, play a role in the carbon cycle, they produce methane and inhabit extreme environments like salt flats.

Can Archaebacteria Live in Water?

Yes, many Archaebacteria species can live in water, including extreme environments like hot springs and deep-sea hydrothermal vents.

Explain the Archaebacteria Cell Type?

Archaebacteria have prokaryotic cells lacking a nucleus and membrane-bound organelles, featuring unique cell walls and membranes adapted to extreme conditions.