Domain bacteria

Bacteria are also prokaryotic; their domain comprises cells that have bacterial rRNA, lack a nuclear membrane, and have mostly diacyl glycerol diester lipids in their membranes. Historically categorised as bacteria, they flourish in the same surroundings as humans and were the first prokaryotes found; they were briefly referred to as the Eubacteria or “real” bacteria until the Archaea were recognised as a different group. The majority of known harmful prokaryotic species are bacteria. As a result of this, and since Archaea are notoriously difficult to cultivate in the laboratory, Bacteria are currently more thoroughly investigated than Archaea.

Characteristics of bacteria

Bacteria is a domain that contains the prokaryotes that people come into contact with on a daily basis. The vast majority of bacterial species are heterotrophic, which means that they obtain their sustenance from organic substances. Bacteria that are saprobic, or those feed on dead or decaying organic matter, constitute the majority of the population. A small number of bacterial species are parasitic, meaning that they dwell within host organisms and cause disease in those animals.

Certain bacteria are autotrophic, which means that they produce their own food from scratch. The photosynthesis process is carried out by bacteria like these. For photosynthetic reactions, they make use of pigments that are dissolved in their cytoplasm. The green sulphur bacteria and the purple bacteria are two types of photosynthetic bacteria that can be found in nature. The pigments found in these bacteria are similar to those found in plants. Chemosynthetic bacteria are found in several autotrophic microorganisms. These bacteria use chemical reactions as a source of energy, and they use this energy to create the meals that they consume.

Bacteria can survive in a wide range of temperature conditions. Bacteria that thrive at extremely low temperatures are known as psychrophilic bacteria, bacteria that thrive at human body temperatures are known as mesophilic bacteria, and bacteria that thrive at extremely high temperatures are known as thermophilic bacteria. Anaerobic bacteria, on the other hand, are those that do not require oxygen for their metabolism. 

Aerobic bacteria are those that require oxygen for their metabolism, while anaerobic bacteria do not. Some bacteria, known as facultative bacteria, may survive in either an oxygen-rich or an oxygen-depleted environment. Generally speaking, bacteria thrive in surroundings with a neutral (pH 7), but some bacteria can thrive in acidic environments (such as those found in yoghurt and sour cream), while others can thrive in alkaline environments. It is known that certain bacteria may survive at the pH of 2 that is found in the human stomach.

Activities of bacteria

Bacteria have a wide range of beneficial effects on the environment. In the case of legumes, for example, some bacteria species that reside on the roots of the plant’s “fix” nitrogen from the air into organic compounds that are subsequently available to the plants. The nitrogen compounds are utilised by the plants to produce amino acids and proteins, which are then provided to the animals that consume them. 

Decomposition in landfills and other environmental trash is caused by bacteria that are unrelated to the ones that cause rot. These bacteria recycle the key elements found in organic materials, allowing it to be recycled again.

Bacteria are employed in the food business to make items such as cheeses, fermented dairy products, sauerkraut, and pickles, among other things. Bacteria are also utilised in a variety of different businesses, including the production of antibiotics, chemicals, dyes, various vitamins and enzymes, and a variety of insecticides. Today, they are utilized in genetic engineering to synthesize some therapeutic compounds that would otherwise be impossible to obtain through conventional means.

Domain bacteria organism and its examples

Proteobacteria, chlamydia, spirochetes, cyanobacteria, and gram-positive bacteria comprise the Domain Bacteria.

Proteobacteria are classified into five groups: alpha, beta, pi, and epsilon. These groupings of species exhibit a wide variety of lifestyles. Some are symbiotic with plants, while others inhabit hot vents deep beneath the sea, while yet others cause human diseases such as stomach ulcers (Helicobacter pylori) and food poisoning (Salmonella).

The other four major bacterial groupings are also quite varied. Chlamydia are pathogens that dwell inside host cells, whereas cyanobacteria are photosynthesizers that produce the majority of the oxygen on Earth. Spirochetes include both benign and pathogenic bacteria, such as Borrelia burgdorferi, which causes Lyme disease. The same is true for Gram-positive bacteria, which include probiotic bacteria found in yoghurt and anthrax-causing Bacillus anthracis.

Domain Viruses

Viruses are the most perplexing organisms to comprehend in this procession of all life. The majority of them consist of a protein coat enclosing a nucleic acid. Even the most complicated viruses have a non-cellular structure and organisation. As a result, their ties with all other living groups are at best murky. Not only are their origins obscure, but they are unquestionably paraphyletic. At least three distinct scenarios exist for their genesis:

They may represent remains of the earliest forms of life, life prior to the development of cells. The scenario postulates that pre-cellular forms of life continued to exist as parasites following the appearance of cells.

Another possibility is that viruses originated as bits of normal cells that remained as parasites.

Thirdly, viruses may have originated as cellular parasites and became extremely rare as a result of their parasitic existence.

From these, it appears as though possibility 3 is the most plausible. However, each of the three scenarios allows for the possibility of viruses having many origins. As a result, every classification scheme is arbitrary. According to the widely accepted system proposed by The International Committee on Virus Taxonomy (ICTV 2005), viruses are classified into three basic categories based on their genomic types. A fourth classification comprises subviral structures (i.e., prions, satellites, and viroids).

• Viruses with DNA

• Viruses with Double-Stranded DNA (dsDNA, 22 families)
• Viruses with a Single-Stranded DNA (ssDNA, 6 families)

• Viruses with Reverse Transcriptase

• Viruses with Double-Stranded DNA Reverse Transcriptase (dsDNA-RT, 2 families)
• Viruses with Single-Stranded DNA Reverse Transcriptase (ssDNA-RT, 3 families)

• Viruses with RNA

• Viruses with Double-Stranded RNA (dsRNA, 7 families)
• Viruses with Negative-Stranded Single-Stranded RNA (-ssRNA, 7 families)
• Positive-Stranded Single-Stranded RNA Viruses (+ssRNA, 24 families) Positive-Stranded Single-Stranded RNA Viruses

• Agents Subviral

• Viruses (2 families)
• Aerial vehicles (2 families)1
• Viruses (1 family)

Conclusion 

Bacteria are single-celled prokaryotic bacteria that are abundant in both living and non-living hosts and across the world (e.g., soil, water). By their very nature, they can be either “beneficial” (beneficial) or “harmful” (damaging) to the health of plants, humans, and other creatures with which they come into contact. A virus is a single-celled organism that requires a living host to thrive; it causes sickness in its host, eliciting an immune response. Bacteria are living organisms; however, scientists are unsure whether viruses are life or non-living; they are generally regarded to be non-living.