Editing Dextran (section)

==Occurrence==
Dextran was discovered by [[Louis Pasteur]] as a microbial product in wine,<ref name=pasteur>{{cite journal | last = Pasteur|first= L. | title = On the viscous fermentation and the butyrous fermentation | journal = [[Bulletin de la Société Chimique de France|Bull. Soc. Chim. Paris]] |issn= 	0037-8968|language = fr| volume = 11 | pages = 30–31 | year = 1861}}</ref> but mass production was only possible after the development by [[Allene Jeanes]] of a process using [[bacteria]].<ref name="Human"/> [[Dental plaque]] is rich in dextrans.<ref>{{cite journal | pmc = 422963 | pmid=4594114 | volume=8 | title=Detection and preliminary studies on dextranase-producing microorganisms from human dental plaque | year=1973 | journal=Infect. Immun. | pages=1009–16 |vauthors=Staat RH, Gawronski TH, Schachtele CF | issue=6 | doi=10.1128/IAI.8.6.1009-1016.1973 }}</ref>  Dextran is a complicating contaminant in the refining of sugar because it elevates the viscosity of [[sucrose]] solutions and fouls plumbing.<ref name=Sidebotham>{{cite journal|journal=Adv. Carbohydr. Chem. Biochem.|year=1974|volume=30|pages=371–444|title=Dextrans|author=Sidebotham, R. L.|series=Advances in Carbohydrate Chemistry and Biochemistry|doi=10.1016/s0065-2318(08)60268-1|pmid=4157174|isbn=9780120072309}}</ref>

Dextran is now produced from sucrose by certain [[lactic acid bacteria]] of the family lactobacillus.  Species include ''[[Leuconostoc mesenteroides]]'' and ''[[Streptococcus mutans]]''. The structure of dextran produced depends not only on the family and species of the bacterium but on the strain.  They are separated by fractional precipitation from protein-free extracts using [[ethanol]].  Some bacteria coproduce [[fructan]]s, which can complicate the isolation of the dextrans.<ref name=Sidebotham/>