Production
Penicillin is produced by the fermentation of various types of sugar by the fungus penicillium rubens. The fermentation process produces penicillin as a secondary metabolite when the growth of the fungus is inhibited by stress. It is not produced during active growth. Production is also limited by feedback in the synthesis pathway of penicillin. α-ketoglutarate + AcCoA → homocitrate → L-α-aminoadipic acid → L-lysine + β-lactamThe by-product, l-lysine, inhibits the production of homocitrate, so the presence of exogenous lysine should be avoided in penicillin production. The Penicillium cells are grown using a technique called fed-batch culture, in which the cells are constantly subject to stress, which is required for induction of penicillin production. The available carbon sources are also important: glucose inhibits penicillin production, whereas lactose does not. The pH and the levels of nitrogen, lysine, phosphate, and oxygen of the batches must also be carefully controlled.The biotechnological method of directed evolution has been applied to produce by mutation a large number of Penicillium strains. These techniques include error-prone PCR, DNA shuffling, ITCHY, and strand-overlap PCR. Semisynthetic penicillins are prepared to start from the penicillin nucleus 6-APA. Biosynthesis
Overall, there are three main and important steps to the biosynthesis of penicillin G (benzylpenicillin). The first step is the condensation of three amino acids—L-α-aminoadipic acid, L-cysteine, L-valine into a tripeptide. Before condensing into the tripeptide, the amino acid L-valine must undergo epimerization to become D-valine. The condensed tripeptide is named δ-(L-α-aminoadipyl)-L-cysteine-D-valine (ACV).
Ella may refer to:

Ella (name), most often a feminine given name, but also used as a surname

Places
United States
Ella, Kentucky, an unincorporated community
Ella, Oregon, an unincorporated community
Ella, Pennsylvania, an unincorporated community
Ella, Wisconsin, an unincorporated community
Lake Ella, Tallahassee, Florida

Greenland
Ella Island, an uninhabited island of the Greenland Sea, Greenland

Sri Lanka
Ella, Sri Lanka, a town in Uva, Sri Lanka

Arts and entertainment
Music
Ella (Ella Fitzgerald album), 1969
Ella (Juan Gabriel album), 1980
Ella (Malaysian singer) (born 1966)
"Ella" (Jack de Nijs song), by André Moss, Jack De Nijs, 1973
"Ella", song by Raphael (singer) L. Favio, 1969
"Ella" (José Alfredo Jiménez song)
"Ella", song by The Way (band) J. Hill, R. Hill, 1972
"Ella", song by Bebe from Pafuera Telarañas, 2004
"Ella" (Tan Biónica song), by Argentine group Tan Biónica, 2010

Other
Ella (2016), documentary film about Australian dancer Ella Havelka
Ella Martinez, a protagonist in the Maximum Ride fantasy novel series
Ella (novel), by Uri Geller
the title character of Ella the Elephant, a Canadian animated preschool series

Other uses
ELLA (programming language), hardware design language
435 Ella, a Main belt asteroid
Tropical Storm Ella (disambiguation), several tropical storms
USS Ella, various United States Navy ships
Ella, trade name in the US of ulipristal acetate, an emergency contraceptive

See also
All pages with titles beginning with Ella
"Ella, elle la", a 1987 song by France Gall
Several settlements near Kingston upon Hull, Yorkshire, England, United Kingdom:
East Ella
Kirk Ella
West Ella
Elah (disambiguation)
Aelle (disambiguation)