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Pediococcus

1,131 bytes added, 19:23, 24 November 2015
updates to introduction, and started Hop Resistance section
[[File:Pedio.jpg|thumb|200px|right|Pediococcus - picture taken by Per Karlsson]]
'''Pediococcus''' (often referred to by brewers as "Pedio") are Gram-positive lactic acid bacteria (LAB) used in the production of Belgian style beers where additional acidity is desirable. They are native to plant material and fruits <ref name="ucdavis">[http://wineserver.ucdavis.edu/industry/enology/winemicro/winebacteria/pediococcus_damnosus.html Viticulture & Enology. UC Davis website. Pedioccous damnosus. Retreived 07/28/2015.]</ref>, and often found in spontaneously fermented beer as the primary source of lactic acid production (with ''P. damnosus'' being the only species identified in such beerslambic) <ref>[http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0095384 The Microbial Diversity of Traditional Spontaneously Fermented Lambic Beer. Freek Spitaels, Anneleen D. Wieme, Maarten Janssens, Maarten Aerts, Heide-Marie Daniel, Anita Van Landschoot, Luc De Vuyst, Peter Vandamme. April 18, 2014.]</ref><ref>[[Scientific_Publications#Lambic_and_Spontaneous_Fermentation |Multiple Scientific publications linked on MTF.]]</ref>. The ability to grow in beer is strain dependent rather than species dependent, however genetic differences indicate that ''P. damnosus'' and ''P. claussenii'' are better adapted to surviving in beer than ''P. pentosaceus'' <ref name="Snauwaert">[http://www.biomedcentral.com/content/pdf/s12864-015-1438-z.pdf Comparative genome analysis of Pediococcus damnosus LMG 28219, a strain well-adapted to the beer environment. Isabel Snauwaert, Pieter Stragier, Luc De Vuyst and Peter Vandamme. 2015.]</ref>. Like many bacteria, Pediococci have the ability to [https://en.wikipedia.org/wiki/Horizontal_gene_transfer transfer genes horizontally] without reproduction <ref name="Snauwaert"></ref>. They are aerotolerant facultative anaerobes, which means they grow anaerobically but can also grow in the presence of oxygen <ref>[http://textbookofbacteriology.net/lactics.html Lactic Acid Bacteria. Todar's Online Texbook of Bacteriology. Kenneth Todar, PhD. Pg 1. Retrieved 08/09/2015.]</ref>. Strains found in beer are hop tolerant <ref>[http://www.biomedcentral.com/1471-2164/16/267 Comparative genome analysis of Pediococcus damnosus LMG 28219, a strain well-adapted to the beer environment. Isabel Snauwaert, Pieter Stragier, Luc De Vuyst and Peter Vandamme. April 2015.]</ref>. Due to their continued metabolism of longer chain polysaccharides, acid production will increase with storage time. ''Pediococcus'' can form a [[pellicle]].
''Pediococcus'' may also cause “ropiness” (also called a "sick beer") due to the production of exopolysaccharides. "Ropy" or "sick" beer is more viscous and, in extreme circumstances, can form strands. Sickness effects mostly the mouthfeel and appearance of beer, and may have no influence on the flavor. ''Pediococcus'' species can also produce diacetyl with extended storage time. [[Brettanomyces]] can break down exopolysaccharides and diacetyl produced by ''Pediococcus'' and the two are often used together.
Of all the ''Lactobacillus'' species that have been studied for this behavior (''L. brevis'', ''L. hilgardii'', ''L. plantarum'', and ''L. kunkeei''), only ''L. kunkeei'' was shown to induce the GAF+ gene. Some species of bacteria from the genres ''Staphylococcus'', ''Micrococcus'', ''Bacillus'', ''Listeria'', ''Paenibacillus'', ''Gluconobacter'', ''Sinorhizobium'', ''Escherichia'', ''Serriatia'', and all ''Pediococcus'' species tested also influenced the GAF+ gene in ''Saccharomyces'' <ref name="cross-kingdom"></ref>.
===Hop Resistance===
It has been suggested by research that horizontal gene transfer (transfer of genetic material by means other than reproduction) allows ''Pediococcus'' species (and other LAB) to obtain the genes associated with resistance to hops (primarily multi-drug transporter "horA", along with "hitA" or "horC"). This has been thought to allow ''Pediococcus'' to adapt to living in beer <ref name="Snauwaert"></ref>.
==See Also==
===Additional Articles on MTF Wiki===

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