Bacteria

Bacteria (common noun bacteria, singular bacterium) are a type of biological cell.

Organisms can be classified as unicellular (consisting of a single cell; including bacteria) or multicellular (including plants and animals).

Most bacteria have not been characterised, and only about half of the bacterial phyla have species that can be grown in the laboratory.

The bacterial phyla are the major lineages, known as phyla or divisions, of the domain Bacteria.

Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals.

Perhaps the most elemental structural property of bacteria is their morphology (shape).

Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals.

Spiral bacteria, bacteria of spiral (helical) shape, form the third major morphological category of prokaryotes along with the rod-shaped bacilli and round cocci.

Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals.

A bacillus (plural bacilli) or bacilliform bacterium is a rod-shaped bacterium or archaeon.

They constitute a large domain of prokaryotic microorganisms.

Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms.

Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals.

A coccus (plural cocci) is any bacterium or archaeon that has a spherical, ovoid, or generally round shape.

However several species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy, and bubonic plague.

Pathogenic bacteria are bacteria that can cause disease.

Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere.

Nitrogen fixation is carried out naturally in the soil by a wide range of microorganisms termed diazotrophs and include bacteria such as Azotobacter, and archaea.

However several species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy, and bubonic plague.

Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum.

However several species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy, and bubonic plague.

Cholera is an infection of the small intestine by some strains of the bacterium Vibrio cholerae.

The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial, particularly in the gut flora.

Probiotics are considered generally safe to consume, but may cause bacteria-host interactions and unwanted side effects in rare cases.

However several species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy, and bubonic plague.

Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacterium Mycobacterium leprae.

The most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year, mostly in sub-Saharan Africa.

Tuberculosis (TB) is an infectious disease usually caused by Mycobacterium tuberculosis (MTB) bacteria.

In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy.

Some bacteria were found living in the cold and dark in a lake buried a half-mile deep under the ice in Antarctica, and in the Marianas Trench, the deepest place in Earth's oceans.

In developed countries, antibiotics are used to treat bacterial infections and are also used in farming, making antibiotic resistance a growing problem.

An antibiotic is a type of antimicrobial substance active against bacteria and is the most important type of antibacterial agent for fighting bacterial infections.

The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial, particularly in the gut flora.

Even simple unicellular organisms such as bacteria possess a rudimentary immune system in the form of enzymes that protect against bacteriophage infections.

In developed countries, antibiotics are used to treat bacterial infections and are also used in farming, making antibiotic resistance a growing problem.

The term antibiotic resistance (AR or ABR) is a subset of AMR, as it applies only to bacteria becoming resistant to antibiotics.

The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process.

Decomposition begins at the moment of death, caused by two factors: 1.) autolysis, the breaking down of tissues by the body's own internal chemicals and enzymes, and 2.) putrefaction, the breakdown of tissues by bacteria.

In industry, bacteria are important in sewage treatment and the breakdown of oil spills, the production of cheese and yogurt through fermentation, the recovery of gold, palladium, copper and other metals in the mining sector, as well as in biotechnology, and the manufacture of antibiotics and other chemicals.

Yogurt, yoghurt or yoghourt ( or ; from yoğurt) is a food produced by bacterial fermentation of milk.

The largest number exist in the gut flora, and a large number on the skin.

Intestinal bacteria also play a role in synthesizing vitamin B and vitamin K as well as metabolizing bile acids, sterols, and xenobiotics.

In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy.

The first type of organism to take advantage of this deep-sea energy source is bacteria.

The study of bacteria is known as bacteriology, a branch of microbiology.

Eukaryotic microorganisms possess membrane-bound cell organelles and include fungi and protists, whereas prokaryotic organisms—all of which are microorganisms—are conventionally classified as lacking membrane-bound organelles and include Bacteria and Archaea.

Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes.

However, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria).

Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and rarely harbour membrane-bound organelles.

Eukaryotes are organisms whose cells have a nucleus enclosed within membranes, unlike prokaryotes (Bacteria and Archaea).