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[[File:Pedio.jpg|thumb|200px|right|[https://www.instagram.com/wildandsour/ 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 Retrieved 07/28/2015.]</ref>, and often found in [[Spontaneous_Fermentation|spontaneously fermented ]] beer as the primary source of lactic acid production (with ''P. damnosus'' being the only species identified in lambic[[Lambic]]) <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>. It is also seen as a major source of beer contamination in commercial breweries due to its ability to adapt to and survive in beer. 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 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 generally considered to be 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>. Some species/strains (including individual strains of ''P. damnosus'') can have their growth and acid production inhibited by oxygen <ref name="NAKAGAWA">[https://www.jstage.jst.go.jp/article/jgam1955/5/3/5_3_95/_article TAXONOMIC STUDIES ON THE GENUS PEDIOCOCCUS. ATSUSHI NAKAGAWA, KAKUO KITAHARA. 1959.]</ref>, while some will have better growth and produce more acid in the presence of oxygen (microaerophilic) <ref>[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC357257/ THE NUTRITION AND PHYSIOLOGY OF THE GENUS PEDIOCOCCUS. Erling M. Jensen and Harry W. Seeley. 1954.]</ref><ref>[http://www.microbialcellfactories.com/content/8/1/3#B5 Pediocins: The bacteriocins of pediococci. Sources, production, properties and applications. Maria Papagianni and Sofia Anastasiadou. 2009.]</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 exopolysaccharideswhen exposed to a fresh sugar source. "Ropy" or "sick" beer is more viscous and, in extreme circumstances, can form strands. Sickness effects mostly the mouthfeel and appearance of the beer, and may have no influence on the flavor. It is considered a temporary flaw in sour beer. Some brewers, including Vinnie Cilurzo from Russian River Brewing and some Belgian lambic producers, claim that after the ropiness goes away (generally in 3-6 months <ref name="ropy_time"></ref>) it produces a deeper acidity and mouthfeel, and is viewed as a positive process in the production of sour beer <ref>[http://www.xxlbrewing.com/hb/sour_beer/img_09.html Cilurzo, Vinnie. AHA Sour Beer presentation. 2007.]</ref>. For other brewers, ropy beer is seen as a nuisance due to the beer needing to be aged for a longer period of time, especially when it occurs shortly after bottling. ''Pediococcus'' species can also produce diacetyl with extended storage time<ref name="Garcia-Garcia" />. ''[[Brettanomyces]] '' can break down exopolysaccharides and diacetyl produced by ''Pediococcus'' and the two are often used together.

See ''[[Lactobacillus]]'', ''[[Brettanomyces]]'', ''[[Saccharomyces]]'', and [[Mixed Cultures]], [[Kveik#Commercial_Availability|Kveik]], and [[Nonconventional Yeasts and Bacteria]] charts for other commercially available cultures.  ==Introduction of Characteristics and Taxonomy==''Pediococcus'' can either improve or detract from fermented food products, including beer, wine, and cider. They play an important role in the fermentation of some meats and cheeses. They tend to be the primary souring microorganism in the production of [[Lambic|Belgian lambic]]. Some species have also been isolated from plants, fruit, and fermenting plant material. In wine, ''P. parvulus'' is the most common species found, and in beer ''P. damnosus'' is the most common. ''P. pentosaceus'' tends to be more hop sensitive than ''P. damnosus'' <ref name="Wade_2018">[https://onlinelibrary.wiley.com/doi/full/10.1111/ajgw.12366 Role of Pediococcus in winemaking. M.E. Wade, M.T. Strickland, J.P. Osborn, C.G. Edwards. 2018. DOI: https://doi.org/10.1111/ajgw.12366.]</ref>.  Currently, there are 11 recognized species of ''Pediococcus''. They are ''P. acidilactici'', ''P. argentinicus'', ''P. cellicola'', ''P. claussenii'', ''P. damnosus'', ''P. ethanolidurans'', ''P. inopinatus'', ''P. parvulus'', ''P. pentosaceus'' (subspecies ''pentosaceus'' and ''intermedius''), ''P. siamensis'', and ''P. stilesii''. ''P. cerevisiae'' was reclassified into either ''P. damnosus'' or ''P. pentosaceus''. Other species of ''Pediococcus'' have also been reclassified to other genera in the last couple of decades. ''P. dextrinicus'' is now classified as ''Lactobacillus dextrinicus'', ''P. urinae-equi'' is now classified as ''Aerococcus urinae‐equi'', and ''P. halophilis'' is now classified as ''Tetragenococcus halophilis'' <ref name="Wade_2018" />. Pediococci are described as coccoidal (spherical) or ovoid (egg-shaped) in shape. They are Gram-positive, non-motile (not capable of moving on their own), and non-spore forming. They are obligate homofermentive and typically do not produce CO₂, ethanol, or acetic acid, although there are a few exceptions to this in the literature. They do not produce [https://en.wikipedia.org/wiki/Catalase catalase] (except for some ''P. pentocaseus'' strains which were reported to have pseudo-catalase activity by Simpson and Taguchi 1995) or [https://en.wikipedia.org/wiki/Oxidase oxidase] enzymes. Because of the way that ''Pedioccous'' cells divide, they often appear stuck together in pairs or clumps. They are the only lactic acid bacteria found in wine and beer to do this, so they are easily identifiable at the genus level under a microscope based on their tendency to clump together. When grown on agar that is supplemented with 100 mg/L of pimaricin, the colonies are white-grey with a diameter of about 1 mm. Ropy strains have a high elasticity, and when touched with a needle, long threads can be drawn and sometimes the colonies completely stick to the needle. See [https://onlinelibrary.wiley.com/doi/full/10.1111/ajgw.12366 table 2 from Wade et al. (2018)] for more species identification indicators and what carbohydrates different species can ferment <ref name="Wade_2018" /><ref name="Oevelen_1979">[https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-37-0034 D. Van Oevelen & H. Verachtert (1979) Slime Production by Brewery Strains of Pediococcus Cerevisiae, Journal of the American Society of Brewing Chemists, 37:1, 34-37, DOI: 10.1094/ASBCJ-37-0034.]</ref>. See also:* [https://wol-prod-cdn.literatumonline.com/cms/attachment/fcb6edb6-00be-4757-822c-be0a341a4191/ajgw12366-fig-0001-m.jpg Microscopy image of ''Pediococcus''.]

| [[White LabsBootleg Biology]]/[[Spot Yeast]] || WLP661 Sour Weapon P (''Pediococcus pentosaceus'' Blend) || damnosus ''P. pentosaceus'' blend || High diacetyl producer Perfect for acidifying unhopped wort quickly for kettle or “quick” sours. At 98F, it’s capable of achieving a pH of 3.3 within 18 hours. At 84F, it can reach a pH of 3.5 within 24 hours. With more time, a terminal pH of 3.1 may be reached. ''P. pentosaceus'' can also be used for long-term sours. It is capable of growing and slow growingproducing lactic acid in worts with IBUs as high as 30, though it is recommended for unhopped worts as IBUs over 10 may prevent significant quick souring. Fermentation tempAt ~30 IBU, souring occurs in 2-3 months <ref>[https: 70//www.facebook.com/groups/MilkTheFunk/permalink/1302981419730069/?comment_id=1870460696315469&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Justin Amaral and Per Karlsson on Bootleg biology Sour Weapon hop tolerance. milk The Funk Facebook group. 11/2/2017.]</ref>. This culture may produce antimicrobials called bacteriocins or pediocins. These can inhibit and kill similar species of bacteria like Lactobacillus and other Pediococcus species in mixed-85°F culture fermentations. Read Bootleg Biology's [https://www.facebook.com/BootlegBiology/photos/a.148869931970401.1073741829.124634287727299/465185997005458/?type=1&theater Facebook post] regarding bacteriocins for more info. No signs of ropiness (21exopolysaccharides) have occurred in testing <ref>[http://bootlegbiology.com/product/sour-weapon-pediococcus-pentosaceus-29blend/ Bootleg Biology website.4° C) Retrieved 05/06/2016.]</ref>. Attenuation: 65% It is still unknown how hops will affect souring in a long term scenario. Cell countBootleg Biology is still researching long term effects and awaiting peoples feedback as of 5/23/2016.|- | [[East Coast Yeast]] || ECY33 || ''P. parvulus'' || Isolated from lambic which was refermented with grapes, this strain of ''Pediococcus'' produces lactic acid, diacetyl, and may cause ropiness in beer. Always add ''Brettanomyces'' where ''Pediococcus'' is used <ref name="ecy_website">[http: 50//www.eastcoastyeast.com/wild-80 million cellsstuff.html "Wild Yeast / Brettanomyces /mL Lactic Bacteria". East Coast Yeast website. Retrieved 04/27/2018.]</ref>. |-| [[Escarpment Laboratories]] || Pediococcus Blend || Two ''Pediococcus'' strains (''P. damnosus'' and ''P. pentosaceus'') || This blend of 2 hop-resistant Pediococcus strains (P. damnosus and P. pentosaceus) is intended for use in long-term souring. Neither strain has been observed to produce exopolysaccharides (EPS). We recommend 15 IBU or less in the first generation.|-| [[Inland Island Brewing & Consulting|Inland Island Yeast Laboratories]] || INISBC-998 || ''P. damnosus'' || Gram positive cocci that produces lactic acid. Also produces diacetyl and several proteins that may cause a "rope" to form in the beer. Rope will disappear with time. Oxygen and hop sensitive. 75-90°F Temperature Range. '''No longer available.'''|-| [[Mainiacal Yeast]] (CLOSED) || MYPP1 || ''P. pentocaceus'' || Isolated from a growing marijuana plant. No production of diacetyl or EPS, with a clean acidity. Ferment at 70-100°F <ref name="WL_cellcountsAmaral_Mainiacal">Private correspondence with White Labs Customer Service and Justin Amaral by Dan Pixley. 1001/2924/20152018.</ref>. Homebrew vials contain 35 mL Commercial pitches only.|-| [[Mainiacal Yeast]] (CLOSED) || MYPD1 || ''P. damnosus'' || Isolated from a bottle of slurrybelgian lambic. Produces diacetyl and EPS, and ~1so use in conjunction with ''Brettanomyces''.75 Ferment at 70-2.8 billion cells per vial 90°F <ref name="priess_pitchesAmaral_Mainiacal"/>. Commercial pitches only.|-| [[Omega Yeast Labs]] || OYL-606 || ''P. damnosus'' || This modestly hop tolerant Pedio strain produces a clean lactic tang over time. The strain can produce diacetyl so it is often paired with one or more Brett strains (to consume the diacetyl). While more hop tolerant than the Lacto Blend (OYL-605), IBUs over 5-10 IBU may inhibit souring. Souring time can vary depending on IBU level <ref>[https://omegayeast.com/yeast/bacterial-cultures/pediococcus Pediococcus OYL-606. Omega Yeast Labs website. Retrieved 06/11/2019.]</ref>. EPS production is unknown and has not been observed or reported <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/11709804795968312719576444737219/?comment_id=1171066879588191&reply_comment_id=1171595552868657&total_comments=62719963548031842&comment_tracking=%7B%22tn%22%3A%22R922R%22%7D Conversation with Richard Priess regarding WL Adi Hastings. Milk The Funk Facebook group on OYL Pediococcus EPS production. 06/11/2019.]</ref>. Commercial pitches only.|-| [[Propagate Lab]] || MIP-920 || ''P. damnosus'' || Will sour a finished beer over time to a pH of 3.5 - 3.1. It works well at room temperature and Wyeast homebrew pitchesis hop tolerant. It may produce ropiness <ref>[http://www.propagatelab.com/mip-920pediodamn Propagate Labs website. MIP-920. 10Retrieved 06/3020/20152020.]</ref>.

| [[WyeastRVA Yeast Labs]] || 5733 RVA 601 || ''P. damnosus '' || May cause “ropiness” Lactic acid bacteria used in souring Belgian-style beers such as gueze and produce low levels of diacetyl Lambic. Acid production increases with extended storage time. Temp Temperature range: is 60-95° F (15-35° C). Cell count: 1.0 x 10⁸ (100 million) cells/mL <ref>[https://drive.google.com/folderview?id=0B8CshC9nxYHdZmE4MmoyLXA2WVk&usp=sharing Wyeast Specifications 2015 Retail Products. 2015.]</ref>. Homebrew packs contain 100-125 mL of slurry, and ~10-12.5 billion cells <ref name="priess_pitches"></ref>95°F.

| [[RVA Yeast White Labs]] || RVA 601 WLP661 || ''P. damnosus '' || Lactic acid bacteria used in souring BelgianHigh diacetyl (a.k.a. butter) producer and slow growing. Fermentation temp: 70-style beers such as gueze 85°F (21-29.4° C). Attenuation: 65%. Cell count: 50-80 million cells/mL <ref name="WL_cellcounts">Private correspondence with White Labs Customer Service and LambicDan Pixley. Acid production increases 10/29/2015.</ref>. Homebrew vials contain 35 mL of slurry, and ~1.75-2.8 billion cells per vial <ref name="priess_pitches">[https://www.facebook.com/groups/MilkTheFunk/permalink/1170980479596831/?comment_id=1171066879588191&reply_comment_id=1171595552868657&total_comments=6&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation with storageRichard Priess regarding WL and Wyeast homebrew pitches. 10/30/2015. Temperature range is 60-95º F]</ref>.

| [[Inland Island Brewing & ConsultingWyeast]] || INISBC-998 5733 || ''P. damnosus '' (previously listed as ''P. cerevisiae'') || Gram positive cocci that produces lactic acid. Also produces May cause “ropiness” and produce low levels of diacetyl and several proteins that may cause a "rope" to form in the beer. Rope will disappear with extended storage time. Oxygen and hop sensitive Temp range: 60-95° F (15-35° C). Cell count: 1.0 x 10⁸ (100 million) cells/mL <ref>[https://drive.google.com/folderview?id=0B8CshC9nxYHdZmE4MmoyLXA2WVk&usp=sharing Wyeast Specifications 2015 Retail Products. 2015.]</ref>. 75Homebrew packs contain 100-125 mL of slurry, and ~10-90°F Temperature Range12.5 billion cells <ref name="priess_pitches"></ref>.

<blockquote>"If using 1 pack of 5733 per 5 gallon batch; and either adding to secondary after alcoholic fermentation is complete, or co-inoculating with a SacchSaccharomyces' strain, then a starter would not be necessary. If you did want or need to propagate, I'd recommend 2 liters of 1.030-1.040 wort per pack, incubated at 80-90*F, without agitation." - Michael Dawson, Wyeast.

<blockquote>"We just performed an interesting experiment at The Rare Barrel with pedio. Jay, our head brewer and blender, wanted a more acidic beer that we could use as a blending component while also growing up our diminishing pedio culture. So we racked 2 oak barrels of gold fermented with [[Brettanomyces|Brettanomyces claussenii]] and White Labs ''Pediococcus damnosus '' (WLP661) into one of our 30 bbl batches of 12*p gold wort that had been acidified to about 4.5 pH in the kettle using lactic acid (our first hot side experiment!). No oxygen, really wanted to encourage the bacteria. Within 10 days the pH was 3.6 and the gravity 10.7. We were all surprised how quickly the pedio was working. We eventually racked a "splash" of fermenting gold with BSI Brett D and BSI Lacto D to drop the gravity. The beer had a bright acidity quickly and I was surprised at how well rounded the flavors were when we racked into barrels after a month in the fermenting vessel. This might be a little harder to do at home, but I think there's potential for interesting results. ''Pediococcus'' shines long term traditionally so I agree with the posts above, if you're going for quick acidity I'd go lacto, but I plan on playing around with early ''Pediococcus'' fermentations at home." - Mike Makris from The Rare Barrel <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1041019779259569/?comment_id=1041073789254168&offset=0&total_comments=8 Conversation with Mike Makris on Milk The Funk.]</ref>.</blockquote>

This might be a little harder to do at home, but I think there's potential for interesting results. 'Pediococcus shines long term traditionally so I agree with the posts above, if you're going ' has a reputation for quick being a "slow worker", meaning that it produces acidity I'd go lacto, but I plan on playing around with early Pediococcus fermentations overtime. Staff at home." - Mike Makris from The Rare Barrel noticed that pitching on second generations of White Labs WLP661 ''Pediococcus'' might help the ''Pediococcus'' produce acidity very quickly <refname="SourHour29">[httpshttp://www.facebookthebrewingnetwork.com/groupsthe-sour-hour-episode-29/MilkTheFunkThe Sour Hour Episode 29 on The Brewing Network, interview with The Rare Barrel staff. 02/permalink19/10410197792595692016.]</?comment_id=1041073789254168&offset=0&total_comments=8 Conversation ref> (~19 minutes in). They speculate that oxygen exposure might inhibit acid production with Mike Makris on Milk The Funkthe White Labs WLP661 ''P.]damnosus'' strain, however this is purely speculative and anecdotal <ref name="SourHour29"></ref>(~32 minutes in).

[[File:Pedio sugarsEMP Pathway.JPGjpg|thumb|300200px|Pedio fermentables <ref>Wine Microbiologyright|[https://onlinelibrary. Practical Applications and Procedureswiley.com/doi/full/10. Kenneth C1111/ajgw. Fugelsang12366 Homofermentative Embden–Meyerhof–Parnas (EMP) pathway for the production of lactic acid, acetoin, Charles Gdiacetyl and 2,3‐butanediol and acetic acid production from citrate metabolism. EdwardsImage by Wade et al (2018).</ref>]]]

About 90% of sugar metabolized by ''Pediococcus'' produces both L- and D-lactic acid<ref name="Wade_2018" />. It does so by homolactic fermentation producing primarily lactic acid (same EMP pathway as [[Lactobacillus#Types_of_Metabolism|''Lactobacillus'' homolactic fermentation]]), although some species/strains can convert glycerol to lactic acid, acetic acid, acetoin, and CO2 under aerobic conditions (''P. damnosus'' is not in this category) <ref>[https://books.google.com/books?id=1b1CAgAAQBAJ&pg=RA2-PA1&lpg=RA2-PA1&dq=pediococcus+damnosus+homolactic&source=bl&ots=myI2alVB78&sig=cG-yWB4GuABQFEtqD2CAyKmU0TE&hl=en&sa=X&ved=0CEAQ6AEwBGoVChMI66C5593-xgIVCVKICh3Pcg7c#v=onepage&q=pediococcus%20damnosus%20homolactic&f=false Encyclopedia of Food Microbiology. Pediococcus. Carl A. Batt. Academic Press, Sep 28, 1999 .]</ref>. Some strains of ''P. damnosuspentosaceus'' can ferment glucose, sucrose, five-chain sugars such as xylose to produce acetic acid and galactoselactic acid. Some strains of ''P. damnosushalophilus'' (now reclassified as ''Tetragenococcus halophilis'' ) can ferment maltose convert citric acid into acetic acid and oxaloacetate (oxaloacetate is then further reduced to acetic acid and diacetyl, and the diacetyl is further reduced to acetoin, and 2,3-butanediol) by producing citrate lyase enzyme. This generally occurs at a slower rate than malolactic fermentation and depends on pH and sucrose temperature. However, all species in the ''Pediococcus'' genus are considered obligatory homofermentative because of the pathways that they use <ref name="ucdavis">[http://aem.asm.org/content/81/20/7233.full A Genomic View of Lactobacilli and pediococci Demonstrates that Phylogeny Matches Ecology and Physiology. Jinshui Zheng, Lifang Ruan, Ming Sun and Michael Gänzle. 2015.]</ref>. The disaccharide trehalose is the preferred carbon source for Pediococci <ref name="GeisslerWade_2018"/><ref>[https://aem.asm.org/content/53/6/1257.short Citrate Metabolism by Pediococcus halophilus. Chiyuki Kanbe, Kinji Uchida. 1987.]</ref>.

===Growth Diacetyl and EnvironmentAcetoin===''P. damnosus'' is sensitive to temperature can produce high amounts of diacetyl and pHacetoin during lactic acid production <ref>[http://onlinelibrary. It is unable to grow at a pH wiley.com/doi/10.1046/j.1365-2672.2000.00956.x/pdf Identification of 8 or higher or at 35°Cpediococci by ribotyping. The optimal growth occurs at 22°C R. Satokari, T. Mattila-Sandholm and 5M.5 pHL. ''PSuihko. damnosus'' is sensitive to environments that contain NaCl Journal of Applied Microbiology 2000, 88, and will not grow with concentrations of 4% NaCl 260–265.]</ref><ref name="ucdavis">[http://mmbr.asm.org/content/77/2/157.full The Microbiology of Malting and Brewing. Nicholas A. Bokulicha, and Charles W. Bamforth. June 2013.]</ref>. Most strains of Diacetyl is the 'buttery'P. claussenii'' can grow aroma and flavor found in beer(generally not favorable) and in wine (favorable in amounts between 1-4 mg/L). About half of the strains tested of ''P. damnosus'' can grow While other microbes found in beer, and none to very few strains of wine fermentation (namely ''P. acidilacticiSaccharomyces cerevisiae'') can also produce diacetyl, ''P. parvulusPediococcus'', and ''P. pentosaceus'' have been found other lactic acid bacteria are known to be able to grow in finished beerproduce much higher amounts <ref name="Wade_2018" />.

One study showed that optimal growth was observed in [http://www.neogen.com/Acumedia/pdf/ProdInfo/7406_PI.pdf MRS media] with an initial pH In lactic acid bacteria, diacetyl can be the byproduct of both homofermentative metabolism of sugars as well as the metabolism of 6.7citric acid, and it is a final pH way for the cells to regenerate NADP⁺. In either of 4.14these two pathways, extra pyruvate is turned into alpha-acetolactate which occurred naturally from fermentationthen undergoes an oxidative decarboxylation reaction to produce diacetyl. The addition of bacteriological peptoneDiacetyl is often reduced by yeast to acetoin and/or 2, MnSO43-butanediol, which have a higher threshold and Tween 80 also increased activityless of an impact on the finished beer/wine <ref name="Wade_2018" />. Maximum cell densities In mixed fermentation sour beer, the breakdown of diacetyl into acetoin and 2,3-butanediol is often thought to be carried out by ''Brettanomyces'' in a similar way to ''P. damnosusSaccharomyces'' species, but this has not been investigated that we are around 1-2 billion cells/mL in MRS media aware of . It has been reported that diacetyl reduction is faster at a lower pH of 6around 3.7 ''(editor's note: this number needs 5, which is a typical pH range for sour beer and might be one of the contributing factors to be verified)'' a lack of anecdotal reports of diacetyl in sour beer <ref>[httphttps://wwwonlinelibrary.wiley.com/doi/full/10.1002/jib.381 Michel, M.ncbi, Meier‐Dörnberg, T.nlm, Jacob, F.nih, Methner, F.gov/pubmed/11851822 Growth optimization of Pediococcus damnosus NCFB 1832 and the influence of pH and nutrients on the production of pediocin PD-1‐J. Nel HA, Bauer Wagner, R. S., and Hutzler, Vandamme EJM. (2016) Review: Pure non‐Saccharomyces starter cultures for beer fermentation with a focus on secondary metabolites and practical applications. J. Inst. Brew., Dicks LM122: 569– 587. 2001doi: 10.1002/jib.381.]</ref>, but this is only in optimal conditions. Maximum cell density varies based on the conditions of the propagation with pH and nutrient demands being two of the main limiting factors <refname="krogerus_2013">[https://www.redditresearchgate.comnet/rpublication/Homebrewing259331290_125th_Anniversary_Review_Diacetyl_and_its_control_during_brewery_fermentation Krogerus, K. and Gibson, B.R. (2013), 125th Anniversary Review: Diacetyl and its control during brewery fermentation. J. Inst. Brew., 119: 86-97. https:/comments/3qp7b7doi.org/advanced_brewers_round_table_neva_parker_white10.1002/cwh7iqq Neva Parker, Reddit threadjib. 10/29/201584.]</ref>.

Although more experiments are probably neededSeveral variables the affect diacetyl and acetoin production have been identified. First of all, agitation is believed to be an important factor for any some strains of ''Pediococcus'' species of microbe (yeast produce diacetyl, and bacteria)others do not. Gentle stirring on a stir plate or orbital shakerDuring malolactic fermentation (conversion of citric acid to lactic acid), the temperature at which MLF is conducted can influence whether or frequent gentle manual agitation leads to faster growth and a higher number of organismsnot diacetyl is produced. Agitation keeps For example, two studies reported that more diacetyl and acetoin were produced during the microbes MLF in solutionwine at 18°C compared at 25°C. It also maximizes The effect of temperature is not well understood, but it has been hypothesized that it could be that at lower temperature yeast is less active and thus cannot break the microbes' access diacetyl down to nutrients acetoin and disperses waste evenly2,3-butanediol (extended time exposed to active yeast or on lees can reduce diacetyl in wine and probably also beer). In If SO₂ is used, it can bind to diacetyl in a non-agitated starterform that cannot be tasted, although the microbes are limited to the diffusion rate of nutrients, leading to a slower and more stressful growth SO<refsub>[https://www.facebook.com/groups/MilkTheFunk/permalink/1168024059892473/?comment_id=1174865305875015&reply_comment_id=1176092372418975&total_comments=1&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation with Bryan Heit about starters and agitation. 11/09/2015.]2</refsub>can become unbound and release the diacetyl again. Although ''Pediococcus'' are aerotolerant and oxygen usually does not negatively affect their growth, it is An increase in citric acid can also generally lead to more diacetyl under semi-aerobic conditions but not neededanaerobic conditions. Therefore, it is generally best practice to seal the starter The presence of glucose has also been associated with an airlockhigher levels of diacetyl production in wine <ref name="Wade_2018" />.

Some strains of ''P. damnosus'' can cause a beer (or wine) to go "ropy". Reportedly, ropiness in beer that also has ''Brettanomyces'' (which is traditionally credited with breaking down the ropiness after a period of rest) usually lasts anywhere from 1 week to 3 months, although fewer reports claim that it has lasted as long as 7 months (see reference for different experiences of brewers) <ref>[https://www.facebooktandfonline.com/groups/MilkTheFunk/permalinkdoi/1132030550158491abs/ Poll on Milk The Funk regarding how long ropy beer has been observed10. 081094/20/2015.ASBCJ-37-0034 Oevelen and Verachtert (1979)]demonstrated that ''Brettanommyces bruxllensis'' reduces the viscosity of ropiness produced by ''Pediococcus'', but that at least one strain of ''Saccharomyces cerevisiae'' does not <ref name="Oevelen_1979" /ref>. This "ropiness" is actually caused by production The scientists tested two strains of exopolysaccharides (EPS) in the form ''B. bruxellensis'', and when either one of βthese strains were co-glucans pitched with a strain of ''P. damnosus'' (beta glucansformerly called ''P. cerevisiae''). A small amount , at two weeks there was the same level of β-glucan is adequate enough to affect the visible viscosity of beer or wine. The gene known as "dps" has been identified with when the production of β-glucan/EPS in ''P. damnosus''strain was pitched by itself, and but at 4 weeks the viscosity was greatly reduced (although the gene "gtf" in viscosity was still higher than when there was no ''P. clausseniiPediococcus'' <ref name="Snauwaert"></ref>present). Not all strains When they co-pitched a strain of ''P. damnosusSaccharomyces cerevisiae'' with the ''Pediococcus'' express , the geneviscosity remained high at 4 weeks, and only ones demonstrating that do will cause a beer this strain of ''S. cerervisiae'' was not able to go ropy. Although reduce the viscosity of the ropiness (it is not needed to survive in beer, EPS production is probably has importance in biofilm production <ref>[http://catknown if this strain of ''S.inistcerevisiae'' was diastatic or not).fr/?aModele=afficheN&cpsidt=23890699 Ethanol tolerance The scientists also attempted to stagger the pitch of lactic acid bacteria''Brettanomyces'', including relevance pitching it two weeks after the ''Pediococcus''. This resulted in very low growth of the exopolysaccharide gene gtf. Pittet V, Morrow K, Ziola B. 2011.]</ref>, and ''PediococciBrettanomyces'' and no reduction in viscosity due to that are ropy have been found limited growth. The limited growth was attributed to be more acid, alcohol, and SO2 tolerant than other the low pH that the ''PediococciBrettanomyces''yeast was exposed to at inoculation time. The thickness ''Brettanomyces'' was able to reduce the viscosity when the scientists add another 10 g/L of glucose, and buffered the ropiness pH to 4. The researchers also found that when ropy media was exposed to air, it immediately disappeared. However, exposing ropy beer to air is increased not an acceptable method for dealing with the presence of malic ropiness due to oxidation and acetic acid production in sour beer when it is exposed to oxygen <ref name="ESPOevelen_1979"></ref>. The exact enzymatic activity for how ''Brettanomyces'' (or other microorganisms) break down EPS from ''Pediococcus'' is not well characterized, but it could be due to alpha-glucosidase activity in those yeasts (see [[Brettanomyces#Carbohydrate_Metabolism_and_Fermentation_Temperature|''Brettanomyces'' metabolism]] and [[Pediococcus#Carbohydrate_Metabolism|Carbohydrate Metabolism]] above).

One study showed that This "ropiness" is caused by production of exopolysaccharides (EPS) in the production form of β-glucan coincided with the end of the growth phase of glucans (beta glucans) by some strains ''Pediococcus''and some other lactic acid bacteria species. While small amounts Ropiness also contains 4-15% proteins and nucleic acid in the form of RNA <ref name="Oevelen_1979" />. The β-glucan were produced during growthglucans are made up of beta 1, 3 linkages and beta 1, after 2 days branches composed of growth, β-glucan production increased as growth slowedsingle units <ref name="Wade_2018" />. A small amount (20-30 mg/L <ref name="Wade_2018" />) of β-glucan production stopped when growth stoppedis adequate enough to affect the visible viscosity of beer or wine. This study showed that The gene known as "dps" has been identified with the production of β-glucan production is linked to /EPS in ''PediococcousP. damnosus'' growth, producing more towards and the end of growthgene "gtf" in ''P. claussenii'' <ref name="Snauwaert"></ref>. This would explain why beer containing Not all strains of ''PediococcusP. damnosus'' often goes express the gene, and only ones that do will cause a beer to go ropy shortly after naturally carbonating in the bottle. This study found that other variables were Although it is not factors needed to survive in the beer, EPS production is probably has importance in biofilm production <ref>[http://cat.inist.fr/?aModele=afficheN&cpsidt=23890699 Ethanol tolerance of β-glucanlactic acid bacteria, such differing levels including relevance of alcohol (although alcohol interacts with the β-glucan in a way that makes the viscosity seem thicker)exopolysaccharide gene gtf. Pittet V, Morrow K, Ziola B. The study also found 2011.]</ref>, and pediococci that the lack of agitation increased the β-glucan production (wine makers will often agitate or aerate are ropy wine have been found to cure the wine from ropiness). A higher initial pH encourages higher growth (5.5+)be more acid, which increases β-glucan production. A lower initial pH (3.5)alcohol, decreases growth and β-glucan productionSO2 tolerant than other pediococci. A higher concentration The thickness of glucose the ropiness is increased growth and β-glucan productionwith the presence of malic acid <ref name="ESP"></ref>. A low starting pH decreases growth, While strains of ''P. damnosus'' and therefore decreases β-glucan production''P. Glocuse is needed for β-glucan production. While fructose alone is mostly insufficientparvulus'' are the ''Pediococcus'' species most associated with ropiness, a combination some strains of glucose and fructose was slightly more efficient than glucose alone ''P. pentosaceus'' have also been found to produce EPS <ref name="ESPWade_2018"></ref>.

It has been observed One study showed that the production of β-glucan coincided with the end of the growth phase of ''LactobacillusPediococcus'' species can produce EPS (. While small amounts of β-glucan were produced during growth, after 2 days of growth, β-glucan production increased as growth slowed. β-glucan production stopped when growth stopped. This study showed that β-glucan production is linked to ''Lactococcus lactisPediococcous''growth, ''Lactobacillus delbrueckii''producing more towards the end of growth. This study found that other variables were not factors in the production of β-glucan, such as differing levels of alcohol (although alcohol interacts with the β-glucan in a way that makes the viscosity seem thicker). The study also found that the lack of agitation increased the β-glucan production (wine makers will often agitate or aerate ropy wine to cure the wine from ropiness). A higher initial pH encourages higher growth (5.5+), which increases β-glucan production. A lower initial pH (3.5), ''Lactobacillus casei''decreases growth and β-glucan production. A higher concentration of glucose increased growth and β-glucan production. Glucose is needed for β-glucan production. While fructose alone is mostly insufficient to produce ropiness, a combination of glucose and ''Lactobacillus helveticus'') fructose was slightly more efficient than glucose alone <ref name="ESP"></ref>. The introduction of malic acid, glucose, fructose, and/or nitrogen from things like fruit that is added to sour beer or even sugar added for natural carbonation can trigger ''Pediococcus'' growth and EPS production.

Temperature and nitrogen levels also affect how much EPS is produced. One study found that at 12°C both growth and EPS production was much slower than at 25°C. After 29 days in agar media, the EPS in the 12°C samples tended to reach or slightly exceed the levels in the 25°C samples, which developed equivilant levels of EPS (or slightly less) within 7-13 days. Nitrogen levels also play a significant role, according to this study, particularly at lower fermentation temperatures. At 12°C, nitrogen was more important for the formation of EPS than glucose (although glucose was found to be the most important factor in EPS development overall, which is in agreement with the previously cited study). At 25°C nitrogen levels played a significant role in producing EPS, however less so than glucose levels. In general though, higher availability of nitrogen complimented higher levels of glucose to produce more EPS (and faster/higher cell growth) <ref>[https://www.sciencedirect.com/science/article/pii/S0168160503000606 Exopolysaccharide production by Pediococcus damnosus 2.6 in a semidefined medium under different growth conditions. Maite Dueñas, Arantza Munduate, Aidé Perea, Ana Irastorza. 2003.]</ref>. Stress in the environment such as ethanol and SO₂ has also been shown to induce EPS production, and a lack of available glucose has been associated with eliminating the production of EPS (e.g. malolactic fermentation by ''Pediococcus'' in wine tends not to produce EPS, perhaps due to the lack of glucose in the environment) <ref name="Wade_2018" />. The presence of beta-glucans from barley have been observed to extend both the growth and the viability of ''Lactobacillus'' species in probiotics, indicating that ropiness might be a stress response <ref>[http://www.mdpi.com/1422-0067/15/2/3025/htm Barley β-Glucans-Containing Food Enhances Probiotic Performances of Beneficial Bacteria. Mattia P. Arena, Graziano Caggianiello, Daniela Fiocco, Pasquale Russo, Michele Torelli, Giuseppe Spano, and Vittorio Capozzi. 2014.]</ref><ref>[Filehttp://www.mdpi.com/1422-0067/13/5/6026/htm Beta-Glucans Improve Growth, Viability and Colonization of Probiotic Microorganisms. Pasquale Russo, Paloma López, Vittorio Capozzi, Pilar Fernández de Palencia, María Teresa Dueñas, Giuseppe Spano, and Daniela Fiocco. 2012.]</ref>. One study looked at this effect in beta-glucans produced by ''Pediococcus parvulus'' and found that ''L. plantarum'' had a longer viability in a fermented medium with no additional food source when that medium was first fermented with ''P. parvulus'' and EPS was produced. The ''L. plantarum'' strain that was tested did not ferment the beta-glucans. This suggests that there is an interspecies simbiotic relationship between lactic acid bacteria that produce EPS and those that don't, and when EPS is produced (beta-glucans are present) the bacteria survive longer. The study also observed that more EPSwas produced in an oat based wort and a rice based wort, while no EPS was produced in a barley based wort, suggesting that different food sources influence whether or not EPS is produced <ref>[http://www.mdpi.gif|thumb|300com/1422-0067/18/7/1588/htm In Situ β-Glucan Fortification of Cereal-Based Matrices by Pediococcus parvulus. Adrián Pérez-Ramos, María Luz Mohedano, Paloma López, Giuseppe Spano, Daniela Fiocco, Pasquale Russo, and Vittorio Capozzi. 2017.]</ref>. Pittet et al. (2011) found that the presence of the EPS genes in lactic acid bacteria did not correspond with the ability to survive beer-level ethanol levels or higher, which led to the hypothesis that perhaps EPS provides LAB a way to assist in the formation of [[Quality_Assurance#Biofilms|biofilm]], although this has yet to be demonstrated scientifically <ref>[https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2011-0124-01 Ethanol Tolerance of Lactic Acid Bacteria, Including Relevance of the Exopolysaccharide pathway Gene Gtf. Vanessa Pittet and Kendra Morrow and Barry Ziola. 2011. DOI: https://doi.org/10.1094/ASBCJ-2011-0124-01.]</ref>. Along these same lines, [https://www.academia.edu/27927065/Lysozyme_resistance_of_the_ropy_strain_Pediococcus_parvulus_IOEB_8801_is_correlated_with_beta_glucan_accumulation_around_the_cell Coulon et al. (2012)] reported that an EPS producing strain of ''Pediococcus parvulus'' was more resistant to the antimicrobial enzyme [https://en.wikipedia.org/wiki/Lysozyme lysozyme], which is often added to wine to kill lactic acid bacteria. The beta-glucan EPS formed a "coat" around the cells of the bacteria, thus protecting it from the lysozyme enzyme. When a beta-glucanase enzyme was added to break down the EPS produced by the bacteria, the beta-glucan "coat" disappeared from the cell walls and the lysozyme was once again effective at killing this strain of ''Pediococcus'' <ref>[https://www.academia.edu/27927065/Lysozyme_resistance_of_the_ropy_strain_Pediococcus_parvulus_IOEB_8801_is_correlated_with_beta_glucan_accumulation_around_the_cell Coulon, Joana et al. “Lysozyme Resistance of the Ropy Strain Pediococcus Parvulus IOEB 8801 Is Correlated with Beta-Glucan Accumulation around the Cell.” International Journal of Food Microbiology 159.1 (2012): 25–29. Web.]</ref>. It has been observed that ''Lactobacillus'' species can produce EPS (''Lactococcus lactis'', ''Lactobacillus delbrueckii'', ''Lactobacillus casei'', and ''Lactobacillus helveticus'') <ref name="ESP"></ref>. Some ''Oenococcus oeni'' strains can also produce EPS <ref>[https://pubmed.ncbi.nlm.nih.gov/19659698/ Ciezack G, Hazo L, Chambat G, Heyraud A, Lonvaud-Funel A, Dols-Lafargue M. Evidence for exopolysaccharide production by Oenococcus oeni strains isolated from non-ropy wines. J Appl Microbiol. 2010 Feb;108(2):499-509. doi: 10.1111/j.1365-2672.2009.04449.x. Epub 2009 Jun 30. PMID: 19659698.</ref>. Some species of yeast can also produce EPS, including ''Candida'', ''Cryptococcus'', ''Debaryomyces'', ''Lipomyces'', ''Pichia'' <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2465980936763439/ Zach Taggart. Milk the Funk Facebook group post on EPS from yeast. 01/16/2019.]</ref>, ''Pseudozyma'', ''Rhodotorula'' and ''Sporobolomyces'' <ref name="Gientka_2015">[https://www.researchgate.net/publication/283498621_Exopolysaccharides_from_yeast_insight_into_optimal_conditions_for_biosynthesis_chemical_composition_and_functional_properties_-_review?fbclid=IwAR1X6Y0rnquoF6SD-eH9m6EWpLIefgZJFUJK51NJYBooJWngxEVS2aR3PKE Exopolysaccharides from yeast: insight into optimal conditions for biosynthesis, chemical composition and functional properties - review. Iwona Gientka, Stanisław Błażejak, Stanisław Błażejak, Lidia Stasiak, Lidia Stasiak, Anna Chlebowska-Śmigiel, Anna Chlebowska-Śmigiel. 2015.]</ref>. ====Videos====* [https://www.facebook.com/groups/MilkTheFunk/permalink/4547361381958707/ Highly viscous ropy beer video posted in MTF by Roi Funk Krispen.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/3478055812222608/ Post on MTF by Brandon Jones showing initial ropiness of a beer, and then after aging the ropiness out for 8 weeks.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/1813022388725967/ Other videos on MTF of ropy beer.] ===Bacteriocins===Some strains of ''Pediococcus pentocaseus'' have been found to produce bacteriocins, which are toxins that are produced by the cells that inhibit the growth of other types of bacteria. For example, Bootleg Biology's "Sour Weapon" culture produces antimicrobials called bacteriocins or pediocins (see Bootleg Biology's [https://www.facebook.com/BootlegBiology/photos/a.148869931970401.1073741829.124634287727299/465185997005458/?type=1&theater Facebook post] regarding bacteriocins for more info). These can inhibit and kill similar species of bacteria like ''Lactobacillus'' and other ''Pediococcus'' species in mixed-culture fermentations. Bacteriocin production can be higher when ''Pediococcus pentocaseus'' is co-fermented with other bacteria than when it is fermented on its own <ref>[https://www.frontiersin.org/articles/10.3389/fmicb.2018.02952/abstract Enhanced Bacteriocin Production by Pediococcus pentosaceus 147 in Co-Culture with Lactobacillus plantarum LE27 on Cheese Whey Broth. Carolina Gutiérrez-Cortés, Héctor Suarez, Gustavo Buitrago, Luis A. Nero and Svetoslav D. Todorov. 2018. DOI: 10.3389/fmicb.2018.02952.]</ref>. A strain of ''Pediococcus pentocaseus'' was found to produce a "class II" enteriocin that inhibits the growth of ''E. coli'' and ''Staphylococcus aureus'' <ref>[httphttps://www.sciencedirect.com/science/article/pii/S0740002004000668 Glucose fermentation kinetics S0882401017314559 Antibacterial activity of Lactobacillus plantarum isolated from Tibetan yaks. Lei Wang, Hui Zhang, Mujeeb Ur Rehman, Khalid Mehmood, Xiong Jiang, Mujahid Iqbal, Xiaole Tong, Xing Gao, Jiakui Li. 2017.]</ref>. ''P. damnosus'' also produces an antimicrobial compound called pediocin PD-1, which can inhibit several bacteria spp including ''O. oeni'' <ref>[http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2672.2001.01486.x/full Growth optimization of Pediococcus damnosus NCFB 1832 and the influence of pH and exopolysaccharide nutrients on the production of pediocin PD-1. H.A. Nel1, R. Bauer, E.J. Vandamme and L.M.T. Dicks. Jan 2002.]</ref><ref>[http://www.ncbi.nlm.nih.gov/pubmed/15878403 Purification, partial amino acid sequence and mode of action of pediocin PD-1, a bacteriocin produced by Pediococcus damnosus NCFB 1832. Bauer R, Chikindas ML, Dicks LM. May 2005.]</ref>.  See also:* [[Lactobacillus#Bacteriocins|''Lactobacillus'' bacteriocins]].  ===Malolactic Fermentation===See the [[Cider#Microbes|Cider]] page. ===Biogenic Amines===Biogenic amines are produced by all living things and are present in many fermented beverages. High dosages can lead to health issues such as vomiting, headache, asthma, hypotension, and cardiac palpitation. Thus, biogenic amines have been studied intensely <ref name="Wade_2018" />. For more information on biogenic amines in beer in general, see [http://suigenerisbrewing.com/index.php/2019/01/22/biogenic-amines/ "Fact or Fiction – Biogenic Amines in Beer" by Dr. Bryan Heit]. Some strains of lactic acid bacteria, including ''Pediococcus'', can metabolize amino acids into biogenic amines, and potentially also degrade them <ref>[https://watermark.silverchair.com/0362-028x-60_7_831.pdf Tyramine Formation by ropy Pediococcus spp. during Beer Fermentation. MARIA IZQUlERDO-PULIDO, JOSEP-MIQUEL CARCELLER-ROSA, ABEL MARINE-FONT, and M. CARMEN VIDAL-CAROU. 1996.]</ref><ref>[https://www.researchgate.net/publication/240429641_Effect_of_tyrosin_on_tyramin_formation_during_beer_fermentation Effect of tyrosin on tyramin formation during beer fermentation. Maria Izquierdo-Pulido, M. Carmen Vidal-Carou. 2000.]</ref>. The number of strains capable of producing biogenic amines appears to be very low. [https://link.springer.com/pdf%2F10.1007%2FBF01105812 Weiller and Radler (1976)] found that only one out 28 strains of ''P. cerevisiae'' (later reclassified to ''P. damnosus IOEB8801'' and ''P. pentosaceus'') produced biogenic amines. [https://www.ncbi.nlm.nih.gov/pubmed/973463 Strickland et al. (2016)] found that out of multiple species of ''Pediococcus'', only one strain of ''P. inopinatus'' produced biogenic amines, and it only produced 3.3 mg/L of histamine. Emilie Walling[https://www.sciencedirect.com/science/article/pii/S0168160511002893 García‐Ruiz et al. (2011)] reported that 9 out of 85 strains of ''P. parvulus'' and ''P. pentosaceus'' were able to degrade some biogenic amines (histamine, tyrosine, and putrescine) in culture media, but were unable to do so in wine, indicating that any degradation of biogenic amines in wine that might occur is not likely due to lactic acid bacteria, but due to some other cause <ref name="Wade_2018" />.  Izquierdo-Pulido et al. (1995) found that out of 35 samples of Spanish lagers contaminated with ''Pediococcus'', Marguerite Dols21 of them had final tyramine levels between 5-Lafargue10 mg/l, 6 of them had no detected tyramine, and 8 of them had high levels around 25 mg/l, Aline Lonvaudwith higher levels being correlated to higher cell counts of ''Pediococcus''. higher levels of tyramine were associated with higher cell counts of the tyramine-producing strains during smaller bench test fermentations as well. There was no correlation between the presence of wild yeast and tyramine production. Filtration and pasteurization after fermentation had no effect on the levels of tyramine in the final beers <ref>[https://watermark.silverchair.com/0362-028x-Funel59_2_175.pdf Biogenic Amine Changes Related to Lactic Acid Bacteria During Brewing. Food Microbiology Volume 22MARIAI ZQUIERDO-PULIDO, JUDIT FONT-FABREGAS, Issue 1JOSEP-MIQUEL CARCELLER-ROSA, January 2005ABEL MARINE-FONT, Pages 71–78and CARMENVIDAL-CAROU. 1995.]</ref>. De Roos et al (2024) found the ''P. damnosus'' in two samples of lambic had the genetic capability to produce histamine. The total biogenic amine content of the lambic was at levels below that which has been deemed safe by European regulatory bodies <ref name="Roosa_2024"/>.  See also:* [[Spontaneous_Fermentation#Biogenic_Amines|Biogenic amines in spontaneously fermented beer.]]* [[Brettanomyces#Biogenic_Amines|Biogenic amine production by ''Brettanomyces''.]]* [[Wine#Biogenic_Amines|Biogenic amines in wine.]]* [http://www.horscategoriebrewing.com/2019/01/spontaneous-fermentation-and-biogenic.html "Spontaneous fermentation and biogenic amines" by Dr. Dave Janssen; review of several studies that looked at the levels of biogenic amines in different beers and their production, and their potential flavor contribution.]* [http://suigenerisbrewing.com/index.php/2019/01/22/biogenic-amines/ "Fact or Fiction – Biogenic Amines in Beer" by Dr. Bryan Heit; an analysis of biogenic amines in spontaneously fermented beer and associated health concerns.]** [https://www.facebook.com/groups/MilkTheFunk/permalink/2570617069633158/?comment_id=2570641549630710&reply_comment_id=2570664762961722&comment_tracking=%7B%22tn%22%3A%22R8%22%7D Follow up from Dr. Heit on MTF on "allergic-like" reactions to biogenic amines.]

''P. claussenii'' tends to produce a smaller amount of acetic acid than lactic acid in about a 1:3 ratio. ''P. damnosus'' can tends to produce high amounts of diacetyl during only lactic acid production and no acetic acid <refname="Geissler">[http://onlinelibrarywww.wileysciencedirect.com/doiscience/10.1046article/j.1365-2672.2000.00956.xpii/pdf Identification S0168160515301033 Metabolic strategies of pediococci by ribotypingbeer spoilage lactic acid bacteria in beer. RAndreas J. SatokariGeissler, TJürgen Behr, Kristina von Kamp, Rudi F. Mattila-Sandholm and M.L. SuihkoVogel. Journal of Applied Microbiology 2000, 88, 260–2652015.]</ref>, although some strains have been found to produce small amounts of acetic acid of around 100-300 ppm. This level is slightly below and above flavor thresholds in lager beer (but could be additive with other organisms) <ref>[http://mmbronlinelibrary.asmwiley.orgcom/contentdoi/7710.1002/2/157j.2050-0416.full The Microbiology of Malting and Brewing2010. Nicholas Atb00393. Bokulichax/abstract Isolation, Identification, and Charles WCharacterisation of Beer-Spoilage Lactic Acid Bacteria from Microbrewed Beer from Victoria, Australia. Bamforth Garry Menz, Christian Andrighetto, Angiolella Lombardi, Viviana Corich, Peter Aldred, Frank Vriesekoop. June 20132010.]</ref>. ''P. damnosus'' also produces an antimicrobial compound called pediocin PD, but significantly less than the total acetic acid often found in gueuze (around 700-1, which can inhibit several bacteria spp including ''O. oeni'' 2200 ppm <ref>[http://onlinelibrarywww.wileyhorscategoriebrewing.com/doi2016/10.104607/j.1365duivelsbier-2672.2001.01486.x/full Growth optimization of Pediococcus damnosus NCFB 1832 and the influence of pH and nutrients on the production of pediocin PD-1. Hhalle.A. Nel1html Jansen, RDave. Bauer, E Hors Category Blog.J "Duivelsbier of Halle". Vandamme and L.M.T. Dicks 07/30/2016. Jan 2002Retrieved 01/31/2018.]</ref>) and Flanders reds (300-2300 ppm <ref>[http://www.ncbisciencedirect.nlm.nih.govcom/science/article/pubmedpii/15878403 Purification, partial amino acid sequence S0168160515301896 Microbial diversity and mode metabolite composition of action of pediocin PDBelgian red-1brown acidic ales. Isabel Snauwaert, a bacteriocin produced by Pediococcus damnosus NCFB 1832Sanne P. Bauer RRoels, Filip Van Nieuwerburg, Anita Van Landschoot, Chikindas MLLuc De Vuyst, Dicks LMPeter Vandamme. May 20052015.]</ref>). ''P. clausseniiPediococcus'' tends to produce a smaller amount of acetic also carries the decarboxylase enzyme (PAD) which converts hydroxycinnamic acid than lactic acid in about a 1:3 ratio. ''P. damnosus'' tends to produce only lactic acid and no acetic (ferulic acid ) into phenols (4-vinyl guaiacol) <ref name="Geisslerlentz_2018">[http://www.sciencedirectmdpi.com/science2311-5637/4/article1/pii20/S0168160515301033 Metabolic strategies html#B13-fermentation-04-00020 The Impact of beer spoilage lactic acid bacteria in beerSimple Phenolic Compounds on Beer Aroma and Flavor. Andreas JMichael Lentz. Geissler, Jürgen Behr, Kristina von Kamp, Rudi F 2018. Vogel doi: 10. 20153390/fermentation4010020.]</ref>. ===Mixed Culture Influence===:''Editor's note: special thanks to Richard Preiss of [[Escarpment Yeast Laboratories]] for helping to interpret the science referenced this section.''

While ''P. damnosusPediococcus'', as well as some other bacteria, have has been shown linked to alter the expression creation of genes acrolein via the metabolism of glycerol, evidence supports that this is very rare in most, but not all, [[Saccharomyces]] cerevisiae strains (and other ''SacchPediococcus'' species and even perhaps [[Brettanomyces]]), in a way that changes how they ferment sugars. In wine, and essentially forms a symbiotic environment acrolein reacts with the yeast. Normally ''Saccharomyces'' will only ferment glucose when glucose is present anthocyanins and ignores other sugars such as maltose and maltotriose until the glucose is gonephenols to produce an intense bitterness. Biologically speaking, when the presence of glucose Acrolein production in the yeast's environment shuts down the yeast's ability wine has been linked to ferment any other types some strains of sugar besides glucose, this is called "glucose repression" <ref name="cross-kingdom">[http://weitzlab.seas.harvard.edu/files/weitzlab/files/2014_cell_jarosz.pdf Cross-Kingdom Chemical Communication Drives a Heritable, Mutually Beneficial Prion-Based Transformation of Metabolism. 2014. Daniel F. Jarosz, Jessica C.S. Brown, Gordon A. Walker, Manoshi S. Datta, W. Lloyd Ung, Alex K. Lancaster, Assaf Rotem, Amelia Chang, Gregory A. Newby,David A. Weitz, Linda F. Bisson, and Susan Lindquist. Cell. 2014 Aug 28;158(5):1083-93.]</ref>. ''SaccharomycesLactobacillus'' and '. Some strains of 'Brettanomyces bruxellensis'' (it is currently not known if other ''Brett'' species other than ''B. bruxellensisPediococcus'' have this ability) have a gene called "GAF+" that when expressed actually allows it been found to bypass this "glucose repression" metabolize gylcerol in beer and wine under aerobic and ferment semi-aerobic environments, but the metabolism of glycerol in the other sugars simultaneously. Normally this gene is not expressed except by a very small number presence of oxygen results in the production of cells <ref>[http://www.cell.com/cell/abstract/S0092-8674(14)00974-X An Evolutionarily Conserved Prion-like Element Converts Wild Fungi from Metabolic Specialists to Generalists. Daniel F. Jaroszlactic acid, Alex K. Lancasteracetic acid, Jessica C.S. Browndiacetyl, Susan Lindquist. Cell. Volume 158and 2, Issue 53-butanediol, p1072–1082, 28 August 2014]and not acrolein <ref name="Wade_2018" /ref>.

When ''P. damnosus'' lives together with ''Saccharomyces'', a chemical is produced by ''P. damnosus'' that essentially "turns ==Storage==For instructions on" the GAF+ gene in ''Saccharomyces''. Not only does ''Sacch'' then have the ability how to ferment other sugars make slants at the same time as glucose, but it produces less alcohol. Viability over time is also increased in ''Sacch'' cells that express this gene versus those that don't. In wild fermentation home capable of grapesstoring any microbe for potentially 2+ years, the wild GAF+ ''Sacch'' strains thrived over the other types of fungi that were found on the wild grapes[http://suigenerisbrewing. This led the researchers of the referenced study to speculate that the GAF+ gene may play a role in preventing other fungi from thrivingblogspot. It is thought that this benefits both microorganisms, which are often found together in the wild during fermentation of fruit; the bacteria isn't killed by higher alcohol levels, and the com/2015/11/easy-home-yeast has a broader food source. Furthermore, once a ''Saccharomyces'' cell expresses the gene, it will continue to pass this gene onto its offspring. In winemaking, this is the cause of arrested wine fermentations due to the lower amount of alcohol produced. For example in the referenced study, the GAF- ''Sacch'' cells fermented grape must into a 12% ABV wine, banking-and the GAF+ ''Sacch'' cells fermented the same wine must into an 8% ABV wine <ref name="cross-kingdom"></ref>video. However, the implications of this in sour beer brewing are much different and have yet to be explored scientificallyhtml see Bryan's video on Sui Generis Brewing (requires a pressure cooker)].

Of all the ''Lactobacillus'' species Justin Amaral recommends using isotonic sodium chloride and freezing media that have been studied is meant for this behavior 32°F freezers (''Llasts around 2 years) <ref>[https://www. brevis'', ''Lfacebook. hilgardii'', ''Lcom/groups/MilkTheFunk/permalink/1859788084049397/?comment_id=1859790364049169&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Justin Amaral. plantarum Milk The Funk Facebook comment on storing '', and Pediococcus''L. kunkeei''), only ''L 10/23/2017. 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>.