Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. A few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, are present in most of its habitats. Bacteria inhabit soil, acidic hot springs, radioactive waste, the deep biosphere of the earth's crust. Bacteria live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, only about 27 percent of the bacterial phyla have species that can be grown in the laboratory; the study of bacteria is known as a branch of microbiology. All animal life on earth is dependent on bacteria for their survival as only bacteria and some archea possess the genes and enzymes necessary to synthesize vitamin B12 known as cobalamin, provide it through the food chain. Vitamin B12 is a water-soluble vitamin, involved in the metabolism of every cell of the human body, it is a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism.
It is important in the normal functioning of the nervous system via its role in the synthesis of myelin. There are 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants and animals. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere; the nutrient cycle includes the decomposition of dead bodies. 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. In humans and most animals the largest number of bacteria exist in the gut, a large number on the skin; the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial in the gut flora.
However, several species of bacteria are pathogenic and cause infectious diseases, including cholera, anthrax and bubonic plague. The most common fatal bacterial diseases are respiratory infections. Tuberculosis alone kills about 2 million people per year in sub-Saharan Africa. Antibiotics are used to treat bacterial infections and are used in farming, making antibiotic resistance a growing problem. 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 and other metals in the mining sector, as well as in biotechnology, the manufacture of antibiotics and other chemicals. Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and harbour membrane-bound organelles. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two different groups of organisms that evolved from an ancient common ancestor.
These evolutionary domains are called Archaea. The word bacteria is the plural of the New Latin bacterium, the latinisation of the Greek βακτήριον, the diminutive of βακτηρία, meaning "staff, cane", because the first ones to be discovered were rod-shaped; the ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, about 4 billion years ago. For about 3 billion years, most organisms were microscopic, bacteria and archaea were the dominant forms of life. Although bacterial fossils exist, such as stromatolites, their lack of distinctive morphology prevents them from being used to examine the history of bacterial evolution, or to date the time of origin of a particular bacterial species. However, gene sequences can be used to reconstruct the bacterial phylogeny, these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage; the most recent common ancestor of bacteria and archaea was a hyperthermophile that lived about 2.5 billion–3.2 billion years ago.
The earliest life on land may have been bacteria some 3.22 billion years ago. Bacteria were involved in the second great evolutionary divergence, that of the archaea and eukaryotes. Here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves related to the Archaea; this involved the engulfment by proto-eukaryotic cells of alphaproteobacterial symbionts to form either mitochondria or hydrogenosomes, which are still found in all known Eukarya. Some eukaryotes that contained mitochondria engulfed cyanobacteria-like organisms, leading to the formation of chloroplasts in algae and plants; this is known as primary endosymbiosis. Bacteria display a wide diversity of sizes, called morphologies. Bacterial cells are about one-tenth the size of eukaryotic cells and are 0.5–5.0 micrometres in length. However, a few species are visible to the unaided eye—for example, Thiomargarita namibiensis is up to half a millimetre long and Epulopiscium fishelsoni reaches 0.7 mm.
The 2019 East Asian Youth Games were to be the first international multi-sport event for countries in East Asia. All eight countries whose National Olympic Committee is recognized by the East Asian Games Association and one country whose National Olympic Committee is recognized by the Oceania National Olympic Committees, would have participated had the games not been cancelled. 1Associate member Taichung, Taiwan was selected to be the host city for the first East Asian Youth Games on October 24, 2014 during the 32nd East Asian Games Association Council Meeting in Beijing, China. The Taichung City Government planned to establish a committee for the Games in December 2014, but this was postponed until June 26, 2015, when the 2019 East Asian Youth Games Organization Committee was set up; this was to be the first time Taichung City had organised an international multi-sport event, as well as being the first East Asian Youth Games. On July 31, 2018, Taichung was stripped of hosting rights after a vote by the East Asian Olympic Committee.
The cancellation was to due to Chinese anger over public calls in Taiwan for a referendum on whether Taiwan should be allowed to compete under the name "Taiwan" at the 2020 Summer Olympics and pro-independence campaign, or should continue to compete under the name "Chinese Taipei", as it has been forced to acquiesce to since the 1970s. There would have been be ten core sports events and two non-core sports events during the East Asian Youth Games; the core events were to be athletics, judo, three to three basketball, table tennis, badminton and beach volleyball. Cycling and canoeing were to be non-core events
The wife of Julius Nepos was the last empress of the Roman Empire in the West, whose husband reigned from 474 through 480, although he was in exile from his capital after 475. His surname, Nepos, he obtained through his marriage, his wife's given name is not in any primary source, all of which report her as the neptis of Leo I the Thracian of the Roman Empire in the East, his spouse Verina. The word neptis could translate as granddaughter, niece or relative, but it is assumed that Julius' wife was Leo's niece, more related by blood to Verina rather than Leo; the historian Malchus reports, "Verina joined in urging this, giving a helping hand to the wife of Nepos, her relative". Julius' marriage may have been part of a pattern of family patronage: "marriage into the imperial family was a advantegeous affair, marriage to an emperor's daughter allowed the son-in-law to hope for the purple". Both emperors and empresses once elevated to their position would attempt to promote relatives to high offices and help them marry into illustrious lineages.
While these extended families on occasion failed to succeed to the throne, they did manage to endure political upheavals and remain prominent for generations. Verina seems to have played her part in advancing relatives. Between 468 and 476, Basiliscus and Nepos assumed high-ranking military positions. All three were related to her by marriage. During the same period, Verina's daughters Ariadne and Leontia were married to Zeno and Marcian an emperor and a usurper, respectively, she may had something to do with the rise to prominence of the barbarian Odoacer, theorised to be her nephew. Cameron, Averil. Late Antiquity: empire and successors, A. D. 425 - 600, Cambridge University Press, ISBN 0-521-32591-9 Page in "The Cambridge ancient history 14" commenting on Verina and her relatives