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This variant of ''S. cerevisiae'' can produce extracellular glucoamylase (also called [https://en.wikipedia.org/wiki/Alpha-glucosidase alpha-glucosidase], which is the same enzyme that ''[[Brettanomyces]]'' produces to break down starches and dextrins). This enzyme is released outside of the cell and can break down the α-1,4 linkages of starches and dextrins releasing glucose that is then fermented by the yeast. The capability to produce this enzyme is encoded by the STA1, STA2, or STA3 genes. Not all strains containing one of these genes produces the glucoamylase enzyme, or are as effective as others at metabolizing dextrins <ref>[https://link.springer.com/article/10.1007%2FBF00365634 STA10: A gene involved in the control of starch utilization by Saccharomyces. Julio Polaina, Melanie Y. Wiggs. 1983.]]</ref><ref>[http://onlinelibrary.wiley.com/doi/10.1002/yea.1102/full Structural analysis of glucoamylase encoded by the STA1 gene of Saccharomyces cerevisiae (var. diastaticus). Ana Cristina Adam, Lorena Latorre-Garcia, Julio Polaina. 2004.]</ref>. It has been reported by some microbiologists that most brewing strains that contain STA1, STA2, or STA3 do produce the glucoamylase enzyme <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1935201836508021/?comment_id=1936604203034451&reply_comment_id=1937166892978182&comment_tracking=%7B%22tn%22%3A%22R7%22%7D Richard Preiss. Milk the Funk thread about STA1 gene correlation to glucoamylase production. 12/31/2017.]</ref><ref name="mbaa_diastaticus">[http://masterbrewerspodcast.com/068-diastaticus-part-1 Matthew Peetz of Inland Island and Tobias Fischborn of Lallemand. "Master Brewers Association Podcast" 12/25/2017.]</ref>(~16 mins). A study that surveyed 18 strains of ''diastaticus'' that contain the STA gene found that only one was not able to ferment dextrins <ref name="Meier-Dörnberg_2018" />. Richard Preiss has also reported that WLP351 has the STA gene, but is not able to ferment dextrins <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1888017211226484/?comment_id=2013050695389801&reply_comment_id=2013355312026006&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Richard Preiss. Milk The Funk Facebook group thread on diastaticus strains that do not ferment dextrins. March 2018.]</ref>. When beer containing this yeast is packaged too early, it will continue to slowly ferment dextrins and cause over-carbonation. When pitching a proper cell count or pitching rate of a ''diastaticus'' yeast strain into the wort, some strains will fully ferment as quickly or nearly as quickly as any other brewers yeast, while other strains may take as long as 16 days to fully ferment a simple 12.4°P (1.050 SG) wort. A highly dextrinous wort may take longer to fully ferment. The problem of slow fermentation in already packaged beer is usually only a concern when ''diastaticus'' is introduced as a very small cell count, for example as an accidental contamination <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1982499288444942/?comment_id=1983013578393513&comment_tracking=%7B%22tn%22%3A%22R1%22%7D Caroline Whalen Taggart. Milk The Facebook post on how quickly diastaticus ferments. 02/09/2018.]</ref>. The enzyme produced by these strains is heat stable and can continue to work on starches and dextrins even after the yeast is killed by heat pasteurization <ref>[https://www.mbaa.com/publications/tq/tqPastIssues/1983/Abstracts/tq83ab19.htm Factors That Control the Utilization Of Wort Carbohydrates by Yeast. G. G. Stewart, I. Russell, and A. M. Sills. MBAA Technical Quarterly, Vol. 20, No. 1, 1983.] </ref>. Almost all strains of ''S. cerevisiae'' var. ''diastaticus'' are able to ulilize all of the sugars found in wort (e.g. glucose, fructose, sucrose, maltose, maltotriose), although one strain tested in a recent study could not efficiently ferment maltose or maltotriose <ref name="Meier-Dörnberg_2018" />. ''S. cerevisiae'' var ''diastaticus'' can grow at 37°C and can also remain viable at refrigeration temperatures <ref>[http://www.ebc2017.com/inhalt/uploads/P095_Begrow.pdf Wade Begrow. "Recent notable microbiological contaminations of craft beer in the United States". Presentation poster at EBC 2017. Retrieved 11/19/2017.]</ref>. Some strains of ''diastaticus'' are as flocculant as typical ale strains, while others are less flocculant <ref name="Meier-Dörnberg_2018" />. One strain of ''diastaticus'', the Belle Saison strain from Lallemand, is killer neutral, which means that killer wine strains will not kill it (it is not verified if Belle Saison is the same as WY3711, although it is suspected to be). Other strains of ''diastaticus'' may or may not be killer neutral (more data is needed; see [[Saccharomyces#Killer_Wine_Yeast|killer wine strains]] for more information on this topic).
Var. ''diastaticus'' contamination in breweries has been a recent hot topic. These strains are effectively eliminated by standard cleaning and sanitation practices, although inadequate cleaning hygiene can lead to biofilm formation which makes them more resistant to cleaning regiments <ref name="Meier-Dörnberg" />. The source of some contaminations has also been suspected to potentially come from yeast suppliers, although there is no known percentage of infections which originate from yeast suppliers versus poor hygiene in the brewery. For example, a lawsuit by Left Hand Brewing Co. accused White Labs as being the source for the brewery's ''diastaticus'' contamination issues (see also [https://www.whitelabs.com/diastaticus this statement by White Labs]) <ref>[https://www.courthousenews.com/wp-content/uploads/2017/11/Left-Hand-v-White-Labs-COMPLAINT.pdf District Court, Boulder County, Colorado. Case Number 2017CV31132. Filed 11/14/2017.]</ref>. Detection of ''S. cerevisiae'' var. ''diastaticus'' as a contaminant can be difficult. Contamination usually occurs as a secondary contaminant (meaning in the packaging system), and can come from contact with beer lines, by air circulation in the area of the packaging equipment, or by insufficient heat treatment of the packaging line. Since a very small number of cells is enough to contaminate beer, contaminations can be sporadic with only a percentage of bottles being contaminated <ref name="Meier-Dörnberg_2018" />. Documented attenuation percentages above 75% for any strain of ''S. cerevisiae'' is also an indicator that the strain could be ''diastaticus'', however, some non-diastaticus strains can also attenuate higher than 75%, so this indicator is not a reliable method to be sure that a given strain is ''diastaticus'' <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2004689559559248/?comment_id=2004695002892037&reply_comment_id=2005133672848170&comment_tracking=%7B%22tn%22%3A%22R1%22%7D Adi Hastings. Milk The Funk Facebook Group post on non-diastaticus strains with high attenuation. 02/27/2018.]</ref><ref name="mbaa_diastaticus" />. Often this contamination can only be detected by sensory testing weeks after packaging. This yeast has reportedly been detected using [http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1981.tb04005.x/pdf LCSM agar plates], although other species of wild ''Saccharomyces'' yeast can grow on this media <ref name="mbaa_diastaticus" />(~18 mins) and PCR DNA analysis is required to give a positive identification of ''diastaticus''. Adding p-coumaric acid or other cinnamic acids to the LCSM agar media which can then test for POF+ yeast and then confirmed for the presence of phenols via a gas chromatography or some other method can also be used to indicate that a yeast might be ''diastaticus'' since there is a high occurrence of ''diastaticus'' to produce phenols from these cinnamic acids <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2149139905114212/?comment_id=2150763631618506&reply_comment_id=2158975484130654&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Shawn Savuto and linked references. Milk The Funk Facebook book post on POF+ correlation with ''diastaticus''. July 2018.]</ref> (see also [https://www.facebook.com/groups/MilkTheFunk/permalink/1903290776365794/ this MTF thread] on using cinnamic acids to identify phenolic off flavor strains). Cheaper methods of doing PCR are recently becoming available, and could help breweries with smaller budgets sufficiently detect this as a contaminant (see [[Laboratory_Techniques#PCR.2FqPCR|PCR Lab Techniques]]). A recent study used agar plates with 15 g/L<sup>-1</sup> of starch as the only nutrient with 40 mg/L<sup>-1</sup> bromophenol blue in anaerobic conditions to detect the fermentation of starch (a pH drop from 5.2 to 4.6-3.0 will change the color of the agar plate to blue/violet). For some of the slower growing strains, 14 days were required to verify that they were ''diastaticus'' while other strains grew as quickly as two days and most strains grew after five days. The yeast cells had to be thoroughly washed of all other carbohydrate material and starved in order to avoid false positives. Using dextrin agar plates instead of starch also led to false positives <ref name="Meier-Dörnberg_2018" />. This starch media has been recommended by Richard Preiss from [[Escarpment Laboratories]] and Justin Amaral from [[Mainiacal Yeast]] <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2149139905114212/?comment_id=2150763631618506&comment_tracking=%7B%22tn%22%3A%22R%22%7D Richard Preiss and Justin Amaral. Milk The Funk Facebook thread on plate media for diastaticus. 06/26/2018.]</ref>. Note that ''diastaticus'' cells look the same under a microscope as regular ''S. cerevisiae'', so cell morphology is not an effective way to identify ''diastaticus'' strains <ref name="Begrow_MBAA">[https://www.mbaa.com/education/webinars/Pages/webcast.aspx?vid=diastaticus Wade Begrow. "S. cerevisiae var. diasttaicus". MBAA webinar. July 2018.]</ref>.
WY3711 saison yeast has been determined to be ''S. cerevisiae'' var. ''diastaticus'' <ref name="preiss_diastaticus" />. Since yeast cannot be patented, many yeast labs are thought to offer this strain to customers. In the [[Saccharomyces#Commercial_Farmhouse.2FBelgian_Strains_of_Saccharomyces|commercial culture]] lists below where we believe a lab is selling this strain or another strain of ''diastaticus'' yeast, we note that it is determined or suspected to be ''diastaticus''.