Differences Between Archaea and Bacteria – Archaea vs Bacteria – Microbiology Note (2023)

What is Bacteria?

• Bacteria are primitive single-celled organisms which form a wide range of diverse organisms in terms of shape, size, and structure and even habitats.
• Bacteria are prokaryotes with a membrane-less nucleus, and are devoid of cell organelles, making their form and function.
• The domain Bacteria comprises organisms that can be found in a variety of types of life, from the highest mountains to within the bodies of other living organisms.
• Certain bacteria are beneficial and aid in many different purposes, such as the production of antibiotics, industrial use as well as biogeochemical cycle. Some are however pathogenic, causing mild to serious diseases.
• Bacteria are among the smallest living organisms that exist and are extremely microscopic. They can be observed under a microscope using several staining procedures.
• Based on the staining methods Based on the staining techniques, bacteria are separated into Gram-positive and Gram-negative bacteria.
• Nearly all species of bacteria possess a cell membrane made consisting of peptidoglycan which shields the bacteria from harmful chemicals. The cytoplasm contains a few cells with ribosomes, and an incipient membrane-less nucleus, which contains genetic material.
• The membrane lipids found in bacteria are made up of fatty acids that are bound to glycerol via ester bonds.
• Bacteria also possess a distinct transcript of RNA known as transfer-messenger (tmRNA).
• The genetic material found in bacteria is DNA. DNA can be transferred to offsprings through asexual reproduction.
• Reproduction occurs via budding, binary fission and fragmentation. However, diverse methods like transduction, transformation, and conjugation are used to facilitate transfers of genetic material.

Examples of Bacteria

Escherichia coli (E. coli)

E. Coli is a microorganism that is used in different research studies. The organisms can be found in many different environments, and most are located in the lower intestines of humans as well as the warm-blooded species of other animals. Most strains from E. coli are harmless however, a few could cause diarrhea that is mild to extreme. Some microbes create Vitamin K and Vitamin B-12.

E. Coli is a Gram-negative, facultative anaerobe that thrives at temperatures of room temperature. It’s rod-shaped, and has a shorter lifecycle, making it suitable to conduct research. E. bacteria are not spores and possess peritrichous flagella.

Lactobacilli

Lactobacillus is a genus of rod-shaped, Gram-positive non-spore-forming microorganisms that belong to the Lactobacilli family. The name is used to describe their ability to make lactose, a byproduct of glucose metabolism. The organisms are typically located in milk or dairy products.

There are many varieties of lactobacillus that are utilized commercially to make fermented milk products as well as other vegetables. Some of the most popular species in the genus include Lactobacillus Brevis as well as Lactobacillus casesi and Lactobacillus plantarum. They are even present in the bodies of living creatures, such as in the vagina and the intestine of human beings.

What is Archaea?

• Archaea is a class of primitive prokaryotes that, based on their distinctive characteristics, are distinct apart from eukaryotes and bacteria.
• The word ‘Archaea’ originated from the Greek word”archaios,” which means primitive or old which refers to the basic design of these organisms.
• They are typically found in extreme environments, such as deep-sea vents, saline water hot springs, even beneath petroleum deposits.
• They are mostly anaerobic and reside in low oxygen environments. The majority of archaea can’t be grown in labs and , therefore, must be identified using methods that are culture-independent.
• Organisms within this category could have similarities to bacteria and Eukaryotes. They possess a nucleus with no membrane, similar to bacteria, but have a number of metabolic pathways, genes and enzymes seen in eukaryotes.
• But, they also possess distinct features. The membrane lipids in archaea are made up of fat acids that are linked to Glycerol molecules by an ether bond, not an ester bond like in eukaryotes and bacteria.
• Since archaea are found in many different environments and environments they are likely to possess distinct pathways for metabolism, as well as genes that help them survive. Halophilic archaea possess a distinct set of genes that restrict the amount of osmosis that occurs which helps them survive.
• The archaea reproduces asexually through fission, budding and fragmentation. The normal division process of meiosis and mitosis is not observed.
• Many archaea assist in the biogeochemical cycle for various elements , including nitrogen, carbon and sulfur.
• There are many archaea that employ anaerobic cell respiration to create methane as the by-product.
• While oxygen-generating photosynthesis isn’t a feature that can occur in these species However, some (phototrophs) make use of sunlight to generate energy.

Examples of Archaea

Sulfolobus

Sulfolobus is an organism genus that are members of the domain of Archaea that are thermophilic and acidophilic in the natural world. They thrive at a pH of 3 to 4 and temperatures of around 80degC. They are most commonly found in springs that are volcanic. The proteins in Sulfolobus are crucial in biotechnology because they are thermostable and are able to function even in low pH. These microorganisms are unique due to the fact that they utilize sulfur as their final electron acceptor during respiration in cells.

This is why they are dependent on sulfur in the heterotrophic or autotrophic modes of nutrition. Sulfolobus was also utilized as a model in the investigation of replication of DNA. Multiple sources of replication were found when studying these organisms. A few species in this genus include Sulfolobus tokodaii as well as Sulfolobus metallicus.

Methanogens

Methanogens are prokaryotes of the domain Archaea that are named because they generate methane as a byproduct from metabolic processes. They are typically found in wetlands and within the digestive tracts of a variety of species of ruminants, and even humans. Certain methanogens are extremophiles. They can be found in hot springs as well as deep-sea vents. There are over 50 methanogens species that have been identified to date and many of them produce methane via different pathways to metabolism.

Certain methanogens lower carbon dioxide when they are in contact with hydrogen, resulting in methane. But, other methanogens create methanol through anaerobic fermentation. Methanogens are used for treating wastewater through biocomposition that is a more efficient and economical wastewater treatment method. The most common methanogen species include Methanosarcina bakeri Methanosarcina Acetivorans as well as Methanococcus maripaludis.

Archaea vs Bacteria