Editing Vitamin A (section)

===Industrial synthesis===
[[File:Ionone beta.svg|thumb|left|class=skin-invert-image|β-ionone ring]]
β-carotene can be extracted from fungus ''Blakeslea trispora'', marine algae ''Dunaliella salina'' or genetically modified yeast ''Saccharomyces cerevisiae'', starting with xylose as a substrate.<ref name="Sun2020">{{cite journal | vauthors = Sun L, Atkinson CA, Lee YG, Jin YS | title = High-level β-carotene production from xylose by engineered Saccharomyces cerevisiae without overexpression of a truncated HMG1 (tHMG1) | journal = Biotechnology and Bioengineering | volume = 117 | issue = 11 | pages = 3522–3532 | date = November 2020 | pmid = 33616900 | doi = 10.1002/bit.27508 | osti = 1651205 | s2cid = 222411819 }}</ref> Chemical synthesis uses either a method developed by [[BASF]]<ref name="β-Carotin-1">Wittig G.; Pommer H.: ''DBP 954247'', 1956</ref><ref name="β-Carotin-2">Wittig G.; Pommer H. (1959). ''Chem. Abstr''. 53: 2279</ref> or a [[Grignard reaction]] utilized by [[Hoffman-La Roche]].<ref>{{cite patent|country = US |number = 2609396 |title = Compounds with the carbon skeleton of beta-carotene and process for the manufacture thereof |pubdate = 2 September 1952 |invent1 = Inhoffen Hans Herloff |invent2 = Pommer Horst }}</ref>

The world market for synthetic retinol is primarily for animal feed, leaving approximately 13% for a combination of food, prescription medication and dietary supplement use.<ref name="Parker2016"/> Industrial methods for the production of retinol rely on chemical synthesis. The first industrialized synthesis of retinol was achieved by the company Hoffmann-La Roche in 1947. In the following decades, eight other companies developed their own processes. β-ionone, synthesized from acetone, is the essential starting point for all industrial syntheses. Each process involves elongating the unsaturated carbon chain.<ref name="Parker2016">{{cite journal|vauthors=Parker GL, Smith LK, Baxendale IR |title=Development of the industrial synthesis of vitamin A |journal=Tetrahedron |volume=72 |issue= 13|pages=1645–1652 |date=February 2016 |doi=10.1016/j.tet.2016.02.029}}</ref> Pure retinol is extremely sensitive to oxidization and is prepared and transported at low temperatures and oxygen-free atmospheres. When prepared as a dietary supplement or food additive, retinol is stabilized as the ester derivatives [[retinyl acetate]] or [[retinyl palmitate]]. Prior to 1999, three companies, Roche, [[BASF]] and [[Rhone-Poulenc]] controlled 96% of global vitamin A sales. In 2001, the European Commission imposed total fines of 855.22 million [[euro]]s on these and five other companies for their participation in eight distinct market-sharing and price-fixing cartels that dated back to 1989.<ref>{{cite news |url=https://www.nytimes.com/2001/11/21/business/vitamin-makers-fined-record-7551-million-in-pricefixing-case.html#:~:text=BRUSSELS%20%2D%2D%20The%20European%20Commission,Holding%20AG's%20(RHHBY)%20F |author=<!--not stated--> |collaboration=Dow Jones Business News |title=Vitamin Makers Fined Record $755.1 Million in Price-Fixing Case |newspaper=The New York Times |date=21 November 2001 |access-date=24 March 2022 |archive-date=24 March 2022 |archive-url=https://web.archive.org/web/20220324195813/https://www.nytimes.com/2001/11/21/business/vitamin-makers-fined-record-7551-million-in-pricefixing-case.html#:~:text=BRUSSELS%20%2D%2D%20The%20European%20Commission,Holding%20AG's%20(RHHBY)%20F |url-status=live }}</ref> Roche sold its vitamin division to [[DSM (company)|DSM]] in 2003. DSM and BASF have the major share of industrial production.<ref name="Parker2016"/> A biosynthesis alternative utilizes genetically engineered yeast species ''Saccharomyces cerevisiae'' to synthesize retinal and retinol, using xylose as a starting substrate. This was accomplished by having the yeast first synthesize β-carotene and then the cleaving enzyme β-carotene 15,15'-dioxygenase to yield retinal.<ref name="Sun2019">{{cite journal | vauthors = Sun L, Kwak S, Jin YS | title = Vitamin A Production by Engineered ''Saccharomyces cerevisiae'' from Xylose ''via'' Two-Phase ''in Situ'' Extraction | journal = ACS Synthetic Biology | volume = 8 | issue = 9 | pages = 2131–2140 | date = September 2019 | pmid = 31374167 | doi = 10.1021/acssynbio.9b00217 | osti = 1547320 | s2cid = 199389319 }}</ref>