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'''''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. 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]]) <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 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 Pediococcipediococci. 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]].

See ''[[Lactobacillus]]'', ''[[Brettanomyces]]'', ''[[Saccharomyces]]'', [[Mixed Cultures]], [[Kveik#Commercial_Availability|Kveik]], and [[Nonconventional Yeasts and Bacteria]] charts for other commercially available cultures.

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>.

| [[Bootleg Biology]]/[[Spot Yeast]] || Sour Weapon P (''Pediococcus pentosaceus'' Blend) || ''P. pentosaceus'' blend || 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 producing 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. At ~30 IBU, souring occurs in 2-3 months <ref>[https://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-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 (exopolysaccharides) have occurred in testing <ref>[http://bootlegbiology.com/product/sour-weapon-pediococcus-pentosaceus-blend/ Bootleg Biology website. Retrieved 05/06/2016.]</ref>. It is still unknown how hops will affect souring in a long term scenario. Bootleg Biology is still researching long term effects and awaiting peoples feedback as of 5/23/2016.

| [[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="Amaral_Mainiacal">Private correspondence with Justin Amaral by Dan Pixley. 01/24/2018.]</ref>. Commercial pitches only.|-| [[Mainiacal Yeast]] (CLOSED) || MYPD1 || ''P. damnosus''|| Isolated from a bottle of belgian lambic. Produces diacetyl and EPS, so use in conjunction with ''Brettanomyces''. Ferment at 70-90°F <ref name="Amaral_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/2719576444737219/?comment_id=2719963548031842&comment_tracking=%7B%22tn%22%3A%22R%22%7D Adi Hastings. Milk The Funk Facebook group on OYL Pediococcus EPS production. 06/11/2019.]</ref>. Commercial pitches only.

| [[Mainiacal YeastPropagate Lab]] || MYPD1 MIP-920 || ''P. damnosus'' || Isolated from Will sour a bottle finished beer over time to a pH of belgian lambic3.5 - 3.1. Produces diacetyl It works well at room temperature and EPS, so use in conjunction with ''Brettanomyces''is hop tolerant. It may produce ropiness <ref>[http://www.propagatelab.com/mip-920pediodamn Propagate Labs website. Ferment at 70MIP-90°F 920. Retrieved 06/20/2020.]</ref name="Amaral_Mainiacal" />. '''Commercial pitches only'''.

====[[Bootleg Biology]] on Sour WeaponP====This product, which is a blend of ''Pediococcus pentosaceus'', can be used for a kettle souring process or a mixed fermentation process. Jeff reported good growth results using 2 grams of calcium carbonate (chalk; CaCO3) per liter of wort for starters of Sour Weapon <ref name="mello_starter">[https://www.facebook.com/groups/MilkTheFunk/permalink/1369904163037794/?comment_id=1370329352995275&reply_comment_id=1370751796286364&comment_tracking=%7B%22tn%22%3A%22R5%22%7D Conversation on MTF with Jeff Mello regarding starters for Pediococcus. 08/08/2016.]</ref>. This same formula might benefit other ''Pediococcus'' starters as well. The CaCO3 serves as a buffering agent that keeps the starter pH from getting too low too fast, and is similar to the concept of buffered growth media for ''Lactobacillus'' (see [[Lactobacillus#Samuel_Aeschlimann.27s_Starter_Procedures|''Lactobacillus'' Starter]]).

Although more experiments are probably needed, agitation is believed to be an important factor for any species of microbe (yeast and bacteria). Gentle stirring on a stir plate or orbital shaker, or frequent gentle manual agitation leads to faster growth and a higher number of organisms. Agitation keeps the microbes in solution. It also maximizes the microbes' access to nutrients and disperses waste evenly. In a non-agitated starter, the microbes are limited to the diffusion rate of nutrients, leading to a slower and more stressful growth <ref>[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 of Sui Generis Blog about starters and agitation. 11/09/2015.]</ref>. Although ''Pediococcus'' are generally considered facultative anaerobes and oxygen usually does not negatively affect their growth, some strains may show less growth in the presence of oxygen and are considered anaerophilic, meaning that the presence of oxygen inhibits their growth (and therefore their acid production) but they can still grow in the presence of O₂. The presence of CO₂ has a positive effect on acid production <ref name="NAKAGAWA"></ref><ref name="Oevelen_1979" /> . Therefore, it is generally best practice to seal the starter with an airlock.

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. pentosaceus'' can ferment five-chain sugars such as xylose to produce acetic acid and lactic acid. Some strains of ''P. halophilus'' (now reclassified as ''Tetragenococcus halophilis'') can 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 temperature. However, all species in the ''Pediococcus'' genus are considered obligatory homofermentative because of the pathways that they use <ref>[http://aem.asm.org/content/81/20/7233.full A Genomic View of Lactobacilli and Pediococci pediococci Demonstrates that Phylogeny Matches Ecology and Physiology. Jinshui Zheng, Lifang Ruan, Ming Sun and Michael Gänzle. 2015.]</ref><ref name="Wade_2018" /><ref>[https://aem.asm.org/content/53/6/1257.short Citrate Metabolism by Pediococcus halophilus. Chiyuki Kanbe, Kinji Uchida. 1987.]</ref>.

===Malolactic FermentationDiacetyl and Acetoin===See the ''P. damnosus'' can produce high amounts of diacetyl and acetoin during lactic acid production <ref>[http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2672.2000.00956.x/pdf Identification of pediococci by ribotyping. R. Satokari, T. Mattila-Sandholm and M.L. Suihko. Journal of Applied Microbiology 2000, 88, 260–265.]</ref><ref>[Cider#Microbes|Ciderhttp://mmbr.asm.org/content/77/2/157.full The Microbiology of Malting and Brewing. Nicholas A. Bokulicha, and Charles W. Bamforth. June 2013.]] page</ref>. Diacetyl is the 'buttery' aroma and flavor found in beer (generally not favorable) and in wine (favorable in amounts between 1-4 mg/L). While other microbes found in beer and wine fermentation (namely ''Saccharomyces cerevisiae'') can also produce diacetyl, ''Pediococcus'' and other lactic acid bacteria are known to be able to produce much higher amounts <ref name="Wade_2018" />.

===Carbohydrate Metabolism===''P. damnosus'' In lactic acid bacteria, diacetyl can ferment glucose, sucrosebe the byproduct of both homofermentative metabolism of sugars as well as the metabolism of citric acid, and galactose. Some strains of ''P. damnosus'' can ferment maltose and sucrose it is a way for the cells to regenerate NADP<ref name="ucdavis"sup>+</refsup>. The disaccharide trehalose In either of these two pathways, extra pyruvate is turned into alpha-acetolactate which then undergoes an oxidative decarboxylation reaction to produce diacetyl. Diacetyl is often reduced by yeast to acetoin and/or 2,3-butanediol, which have a higher threshold and less of an impact on the preferred carbon source for Pediococci finished beer/wine <ref name="GeisslerWade_2018"></ref>. While simple sugars are In mixed fermentation sour beer, the primary food source for ''Pediococcus'', many strains breakdown of ''P. damnosus'' have been observed to produce varying degrees of both alpha diacetyl into acetoin and beta2,3-glucosidase enzymes. Alpha-glucosidase enzymes have the ability butanediol is often thought to break down higher chain sugars, including dextrins, starches, and glucans (possibly even the glucans that are produced be carried out by ''P. damnosusBrettanomyces'' that result in ropy beer). The types of beta-glucosidase enzymes produced by a similar way to ''P. damnosusSaccharomyces'' are thought to perhaps play a role in breaking down monoglycosidic bonds (see [[Glycosides]])species, but cannot break down the more complex diglycosidic bonds which this has not been investigated that we are needed to break down many glycosides that would release flavor and aroma compoundsaware of. Compared to the microbe ''Oenococcus oeni'' which is often used in wine and cider fermentation (malolactic fermentation) and It has been shown to have more impactful beta-glucosidase activity, ''P. damnosus'' reported that diacetyl reduction is thought to be less impactful on glycosides. Unlike ''O. oeni'' which decreases its enzymatic activity in low pH conditions, enzymatic activity of ''P. damnosus'' is very stable faster at a lower pH of around 3-4. Very low concentrations of glucose or fructose (1 g/l) inhibit this enzymatic activity in ''P. damnosus''. The presence of alcohol inhibits the alpha-glucosidase activity in most strains5, which is a typical pH range for sour beer and might contribute be one of the contributing factors to longer lasting ropiness a lack of anecdotal reports of diacetyl in sour beer. The optimal temperature for enzymatic activity in ''P. damnosus'' is between 35-40°C (95-104°F) <ref>[httphttps://onlinelibrary.wiley.com/doi/full/10.11111002/jjib.381 Michel, M.1365-2672, Meier‐Dörnberg, T., Jacob, F., Methner, F.2005‐J.02707, Wagner, R.x/full Screening of Lactobacillus sppS. , and Pediococcus sppHutzler, M. (2016) Review: Pure non‐Saccharomyces starter cultures for glycosidase activities that are important in oenologybeer fermentation with a focus on secondary metabolites and practical applications. J. Inst. ABrew. Grimaldi, E122: 569– 587. doi: 10.1002/jib.381.]</ref><ref name="krogerus_2013">[https://www.researchgate. Bartowskynet/publication/259331290_125th_Anniversary_Review_Diacetyl_and_its_control_during_brewery_fermentation Krogerus, VK. Jiranekand Gibson, B. 2005R. DOI(2013), 125th Anniversary Review: 10Diacetyl and its control during brewery fermentation. J. Inst.1111/jBrew.1365, 119: 86-267297. https://doi.2005org/10.027071002/jib.x84.]</ref>.

[[File:Pedio sugarsSeveral variables the affect diacetyl and acetoin production have been identified.JPG|none|thumb|Pedio fermentables <ref>Wine Microbiology First of all, some strains of ''Pediococcus'' species produce diacetyl, and others do not. During malolactic fermentation (conversion of citric acid to lactic acid), the temperature at which MLF is conducted can influence whether or not diacetyl is produced. Practical Applications For example, two studies reported that more diacetyl and Proceduresacetoin were produced during the MLF in wine at 18°C compared at 25°C. Kenneth CThe 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 diacetyl down to acetoin and 2,3-butanediol (extended time exposed to active yeast or on lees can reduce diacetyl in wine and probably also beer). Fugelsang If SO₂ is used, it can bind to diacetyl in a form that cannot be tasted, Charles Galthough the SO₂ can become unbound and release the diacetyl again. Edwards An increase in citric acid can also lead to more diacetyl under semi-aerobic conditions but not anaerobic conditions. The presence of glucose has also been associated with higher levels of diacetyl production in wine <ref name="Wade_2018" /ref>]].

Some strains of ''P. damnosus'' (and other bacteria) can cause a beer (or wine) to go "ropy", also known as "sick" by [[lambic]] brewers (or more specifically as "the fat sickness, "; “la maladie de la graisse” in French <ref>[https://beerbybart.com/2011/04/03/true-lambic-jean-van-roy-cantillon-sick-beer/ True Lambic: Sick beers and the magic of Cantillon. Beer By Bart blog. Gail Ann Williams. 04/03/2011. Retrieved 04/23/2016.]</ref>). 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 name="ropy_time">[https://www.facebook.com/groups/MilkTheFunk/permalink/1132030550158491/ Poll on Milk The Funk regarding how long ropy beer has been observed. 08/20/2015.]</ref>. Some species of ''Pediococcus'' and other lactic acid bacteria have been reported to also be able to break down ropiness <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1670311836330357/?comment_id=1670331339661740&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Matt Humbard and Joe Idoni. Milk The Funk Facebook group. 04/29/2017.]</ref>. The viscosity of ropy beer has been reported to be higher at the bottom of wooden barrels than near the top, either due to sedimentation or perhaps more growth of ''Pediococcus'' near the bottom of wooden barrels due to yeast autolysis and/or less exposure to oxygen <ref name="Oevelen_1979" />. Despite the popularity of this talking point about ''Pediococcus'' in brewing, a lot of strains of ''Pediococcus'' used in brewing don't seem to produce ropiness, especially strains sourced from beer yeast labs. For example, Richard Preiss of [[Escarpment Laboratories]] reported only seeing ropiness from ''Pediococcus'' sourced from [[lambic]] <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2859721020722760/?comment_id=2859868767374652&comment_tracking=%7B%22tn%22%3A%22R%22%7D Richard Preiss. Milk The Funk Facebook group thread on the frequency of ''Pediococcus'' caused ropiness. 08/20/2019.]</ref>.  [https://www.tandfonline.com/doi/abs/10.1094/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" />. The scientists tested two strains of ''B. bruxellensis'', and when either one of these strains were co-pitched with a strain of ''P. damnosus'' (formerly called ''P. cerevisiae''), at two weeks there was the same level of viscosity as when the ''P. damnosus'' strain was pitched by itself, but at 4 weeks the viscosity was greatly reduced (although the viscosity was still higher than when there was no ''Pediococcus'' present). When they co-pitched a strain of ''Saccharomyces cerevisiae'' with the ''Pediococcus'', the viscosity remained high at 4 weeks, demonstrating that this strain of ''S. cerervisiae'' was not able to reduce the viscosity of the ropiness (it is not known if this strain of ''S. cerevisiae'' was diastatic or not). The scientists also attempted to stagger the pitch of ''Brettanomyces'', pitching it two weeks after the ''Pediococcus''. This resulted in very low growth of the ''Brettanomyces'' and no reduction in viscosity due to that limited growth. The limited growth was attributed to the low pH that the ''Brettanomyces'' yeast was exposed to at inoculation time. The ''Brettanomyces'' was able to reduce the viscosity when the scientists add another 10 g/L of glucose, and buffered the 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 not an acceptable method for dealing with ropiness due to oxidation and acetic acid production in sour beer when it is exposed to oxygen <ref name="Oevelen_1979" />. 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).

This "ropiness" is caused by production of exopolysaccharides (EPS) in the form of β-glucans (beta glucans) by some strains ''Pediococcus'' and some other lactic acid bacteria species. Ropiness also contains 4-15% proteins and nucleic acid in the form of RNA <ref name="Oevelen_1979" />. The β-glucans are made up of beta 1, 3 linkages and beta 1, 2 branches composed of single units <ref name="Wade_2018" />. A small amount (20-30 mg/L <ref name="Wade_2018" />) of β-glucan is adequate enough to affect the visible viscosity of beer or wine. The gene known as "dps" has been identified with the production of β-glucan/EPS in ''P. damnosus'', and the gene "gtf" in ''P. claussenii'' <ref name="Snauwaert"></ref>. Not all strains of ''P. damnosus'' express the gene, and only ones that do will cause a beer to go ropy. Although it is not needed to survive in beer, EPS production is probably has importance in biofilm production <ref>[http://cat.inist.fr/?aModele=afficheN&cpsidt=23890699 Ethanol tolerance of lactic acid bacteria, including relevance of the exopolysaccharide gene gtf. Pittet V, Morrow K, Ziola B. 2011.]</ref>, and ''Pediococci'' pediococci that are ropy have been found to be more acid, alcohol, and SO2 tolerant than other ''Pediococci''pediococci. The thickness of the ropiness is increased with the presence of malic acid <ref name="ESP"></ref>. While strains of ''P. damnosus'' and ''P. parvulus'' are the ''Pediococcus'' species most associated with ropiness, some strains of ''P. pentosaceus'' have also been found to produce EPS <ref name="Wade_2018" />.

One study showed that the production of β-glucan coincided with the end of the growth phase of ''Pediococcus''. 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 ''Pediococcous'' growth, producing more towards the end of growth. This would explain why beer containing ''Pediococcus'' often goes ropy shortly after naturally carbonating in the bottle. 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), 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 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 sited 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>[http://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 EPS was 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.com/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>. No studies have been done on Pittet et al. (2011) found that the growth or survivability 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 present 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 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 in beerproducing 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 more harsh environment than what "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 tested in these studiesonce 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/ Videos Other videos on MTF of ropy beer.]

See also:* [[Lactobacillus#Bacteriocins|''Lactobacillus'' bacteriocins]].  ===Malolactic Fermentation===See the [[Cider#Microbes|Cider]] page.

See also:===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 [[Lactobacillus#Bacteriocins|''Lactobacillus'' bacteriocins]http://suigenerisbrewing.com/index.php/2019/01/22/biogenic-amines/ "Fact or Fiction – Biogenic Amines in Beer" by Dr. Bryan Heit].

===Diacetyl===Some strains of lactic acid bacteria, including ''P. damnosusPediococcus'' , can produce high amounts of diacetyl during lactic acid production metabolize amino acids into biogenic amines, and potentially also degrade them <ref>[httphttps://onlinelibrarywatermark.wileysilverchair.com/doi/10.1046/j.13650362-028x-2672.200060_7_831.00956.x/pdf Identification of pediococci Tyramine Formation by ribotypingPediococcus spp. Rduring Beer Fermentation. SatokariMARIA IZQUlERDO-PULIDO, JOSEP-MIQUEL CARCELLER-ROSA, T. MattilaABEL MARINE-Sandholm FONT, and M.L. SuihkoCARMEN VIDAL-CAROU. Journal of Applied Microbiology 2000, 88, 260–2651996.]</ref><ref>[httphttps://mmbrwww.asmresearchgate.orgnet/contentpublication/77240429641_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.]</2/157ref>.full The Microbiology number of Malting strains capable of producing biogenic amines appears to be very low. [https://link.springer.com/pdf%2F10.1007%2FBF01105812 Weiller and BrewingRadler (1976)] found that only one out 28 strains of ''P. cerevisiae'' (later reclassified to ''P. damnosus'' and ''P. pentosaceus'') produced biogenic amines. Nicholas A[https://www. Bokulichancbi.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 Charles Wit only produced 3. Bamforth3 mg/L of histamine. June 2013[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" /ref>.

===Other Metabolites===''PIzquierdo-Pulido et al. claussenii'' tends to produce a smaller amount (1995) found that out of 35 samples of acetic acid than lactic acid in about a 1:3 ratio. Spanish lagers contaminated with ''P. damnosusPediococcus'' tends to produce only lactic acid and no acetic acid <ref name="Geissler">[http:, 21 of them had final tyramine levels between 5-10 mg//www.sciencedirect.com/science/article/pii/S0168160515301033 Metabolic strategies l, 6 of beer spoilage lactic acid bacteria in beer. Andreas J. Geisslerthem had no detected tyramine, Jürgen Behr, Kristina von Kamp, Rudi F. Vogel. 2015.]<and 8 of them had high levels around 25 mg/ref>l, although some strains have been found with higher levels being correlated to produce small amounts higher cell counts of acetic acid of around 100-300 ppm''Pediococcus''. This level is slightly below and above flavor thresholds in lager beer (but could be additive higher levels of tyramine were associated with other organisms) <ref>[http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.2010.tb00393.x/abstract Isolation, Identification, and Characterisation higher cell counts of Beerthe tyramine-Spoilage Lactic Acid Bacteria from Microbrewed Beer from Victoria, Australiaproducing strains during smaller bench test fermentations as well. Garry Menz, Christian Andrighetto, Angiolella Lombardi, Viviana Corich, Peter Aldred, Frank VriesekoopThere was no correlation between the presence of wild yeast and tyramine production. 2010.]</ref>, but significantly less than Filtration and pasteurization after fermentation had no effect on the total acetic acid often found levels of tyramine in gueuze (around 700-2200 ppm the final beers <ref>[httphttps://wwwwatermark.horscategoriebrewingsilverchair.com/2016/07/duivelsbier0362-of028x-halle59_2_175.html Jansen, Dave. Hors Category Blogpdf Biogenic Amine Changes Related to Lactic Acid Bacteria During Brewing. "Duivelsbier of Halle". 07/30/2016. Retrieved 01/31/2018.]</ref>) and Flanders reds (300MARIAI ZQUIERDO-2300 ppm <ref>[http://www.sciencedirect.com/science/article/pii/S0168160515301896 Microbial diversity and metabolite composition of Belgian redPULIDO, JUDIT FONT-brown acidic ales. Isabel Snauwaert, Sanne P. Roels, Filip Van Nieuwerburg, Anita Van Landschoot, Luc De VuystFABREGAS, Peter Vandamme. 2015.]</ref>). ''Pediococcus'' also carry the decarboxylase enzyme (PAD) which converts hydroxycinnamic acid (ferulic acid) into phenols (4JOSEP-vinyl guaiacol) <ref name="lentz_2018">[http://www.mdpi.com/2311MIQUEL CARCELLER-5637/4/1/20/html#B13ROSA, ABEL MARINE-fermentation-04FONT, and CARMENVIDAL-00020 The Impact of Simple Phenolic Compounds on Beer Aroma and Flavor. Michael Lentz. 2018CAROU. doi: 10.3390/fermentation40100201995.]</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===Mixed Culture Influence==="Roosa_2024"/>.

See also:* [[Lactic AcidSpontaneous_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.]

===Hop ResistanceOther Metabolites===''PediococcusP. claussenii'' tends to produce a smaller amount of acetic acid than lactic acid in about a 1:3 ratio. ''P. damnosus'' species and strains are generally resistant tends to hop compounds, produce only lactic acid and have been reported to grow in beer with at least 30 IBU no acetic acid <ref name="Geissler">[http://www.sciencedirect.com/science/article/pii/S0168160515301033 Metabolic strategies of beer spoilage lactic acid bacteria in beer. Andreas J. Geissler, Jürgen Behr, Kristina von Kamp, Rudi F. Vogel. 2015.]</ref>, and together with ''Lactobacillus'' are reported although some strains have been found to be responsible for ~70% produce small amounts of acetic acid of all around 100-300 ppm. This level is slightly below and above flavor thresholds in lager beer spoilage incidents caused by microbes (but could be additive with other organisms) <ref name="Garcia-Garcia">[http://onlinelibrary.wiley.com/doi/10.1002/jibj.2050-0416.3972010.tb00393.x/abstract Pediococcus damnosus strains isolated Isolation, Identification, and Characterisation of Beer-Spoilage Lactic Acid Bacteria from Microbrewed Beer from a brewery environment carry the horA geneVictoria, Australia. Garry Menz, Christian Andrighetto, Angiolella Lombardi, Viviana Corich, Peter Aldred, Frank Vriesekoop. Jorge Hugo Garcia-Garcia2010.]</ref>, Luis Cástulo Damasbut significantly less than the total acetic acid often found in gueuze (around 700-Buenrostro, Juan Carlos Cabada2200 ppm <ref>[http://www.horscategoriebrewing.com/2016/07/duivelsbier-Amaya, Myriam Eliasof-Santoshalle.html Jansen, Benito Pereyra-AlférezDave. 2017Hors Category Blog. DOI: 10"Duivelsbier of Halle".1002 07/30/jib2016.397 Retrieved 01/31/2018.]</ref>. It has been suggested by research that horizontal gene transfer (transfer of genetic material by means other than reproduction) allows ''Pediococcus'' species and Flanders reds (300-2300 ppm <ref>[http://www.sciencedirect.com/science/article/pii/S0168160515301896 Microbial diversity and other LAB) to obtain the genes associated with resistance to hops (primarily multimetabolite composition of Belgian red-drug transporter "horA"brown acidic ales. Isabel Snauwaert, Sanne P. Roels, Filip Van Nieuwerburg, along with "hitA"Anita Van Landschoot, "horC"Luc De Vuyst, and "horB" Peter Vandamme. 2015.]</ref name="Garcia-Garcia" />). This has been thought to allow ''Pediococcus'' to adapt to living in beer <ref name="Garciaalso carries the decarboxylase enzyme (PAD) which converts hydroxycinnamic acid (ferulic acid) into phenols (4-Garcia" />vinyl guaiacol) <ref name="Snauwaertlentz_2018">[http://www.mdpi.com/2311-5637/4/1/20/html#B13-fermentation-04-00020 The Impact of Simple Phenolic Compounds on Beer Aroma and Flavor. Michael Lentz. 2018. doi: 10.3390/fermentation4010020.]</ref>.

While able ''Pediococcus'' has been linked to grow in the presence creation of hops, acrolein via the presence metabolism of hops still inhibits glycerol, evidence supports that this is very rare in ''P. damnosusPediococcus''. For example, one study found that in the presence of 15 IBU, lactic acid production was reduced by ~82%species. Exposure to 15 IBU also increased diacetyl production by 350%, while 2,3-pentanedione (buttery, nutty, toastedIn wine, caramellic, diacetyl acrolein reacts with anthocyanins and acetoin notes <ref>[http://www.thegoodscentscompany.com/data/rw1003991.html "acetyl propionyl "other phenols to produce an intense bitterness. The Good Scents CompanyAcrolein production in wine has been linked to some strains of ''Lactobacillus''. Retrieved 01/18/2017.]</ref>) was decreased by 25%. Interestingly, exposure Some strains of ''Pediococcus'' have been found to 3% ABV metabolize gylcerol in beer and no hops reduced the production of diacetyl wine under aerobic and 2,3semi-pentanedione by about 20%. The addition of vitamins, specifically thiamine (vitamin B1) and riboflavin (vitamin B2)aerobic environments, increased but the production metabolism of lactic acid glycerol in the presence of 15 IBU or no hops by about 15-30%. However, thiamine also increased diacetyl oxygen results in the production by 100-125% and 2of lactic acid,3-pentadione production by 20-30% without the presence of hops. In the presence of 15 IBUacetic acid, thiamine and/or riboflavin increased diacetyl production by about 26-36% , and 2,3-pentadione by about 40-114% <ref>[http://onlinelibrary.wiley.com/doi/10.1002/jib.385/full The influence of thiamine and riboflavin on various spoilage microorganisms commonly found in beer. Barry Hucker, Melinda Christophersenbutanediol, Frank Vriesekoop. 2017.]</ref>. Strains that are grown exposed to small amounts of iso-alpha acids can be adapted to survive higher amounts up to ~150 μg mL¹. The implications of this in brewing mean that the bacteria can enter any stage of the process and remain in undetectable amounts until it adapts to higher IBU conditions and then potentially spoils beer not acrolein <ref name="Garcia-GarciaWade_2018" />.