Changes

''Saccharomyces cerevisiae'' var. ''diastaticus'' is a variant of ''S. cerevisiae'' that can ferment certain types of starches and dextrins, and has been identified as a contaminant in breweries and is responsible for a few large recalls. This variant can produce extracellular glucoamylase that can break down starches into simpler sugars that are then fermented by the yeast and cause over-carbonation. 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, and it was found that STA10 is also required to produce the enzyme <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>. However, it has been reported by some microbiologists that most (if not all) brewing strains that contain STA1, STA2, or STA3 do produce the glucoamylase enzyme <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). This report is directly contradicted by White Labs regarding their strains with this gene [https://whitelabs.com/yeast-bank/wlp590-french-saison-ale-yeast WLP590], [https://www.whitelabs.com/yeast-bank/wlp099-super-high-gravity-ale-yeast WLP099], and [https://www.whitelabs.com/yeast-bank/wlp045-scotch-whisky-yeast WLP045] (it is likely that the strains reported by other microbiologists to be ''diastaticus '' are the same as these White Labs strains, but this has not been verified). This yeast has also 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''. Documented attenuation percentages above 75% for any strain of ''S. cerevisiae'' is also an indicator that the strain is ''diastaticus'' <ref name="mbaa_diastaticus" /> Diastaticus contamination in breweries has been a recent hot topic, and the source of some contaminations has been suspected to come from certain yeast suppliers <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>.