Changes

===Mixed Culture Influence===

''P. damnosus'', as well as some other bacteria, have been shown to alter the expression of genes in most, but not all, [[Saccharomyces]] cerevisiae strains (and other ''Sacch'' species and even perhaps [[Brettanomyces]]), in a way that changes how they ferment sugars, and essentially forms a symbiotic environment with the yeast. Normally ''Saccharomyces'' will only ferment glucose when glucose is present and ignores other sugars such as maltose and maltotriose until the glucose is gone. Biologically speaking, when the presence of glucose in the yeast's environment shuts down the yeast's ability to ferment any other types 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>. ''Saccharomyces'' and ''Brettanomyces bruxellensis'' (it is currently not known if other ''Brett'' species other than ''B. bruxellensis'' have this ability) have a gene called "GAF+" that when expressed actually allows it to bypass this "glucose repression" and ferment the other sugars simultaneously. Normally this gene is not expressed except by a very small number 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. Jarosz, Alex K. Lancaster, Jessica C.S. Brown, Susan Lindquist. Cell. Volume 158, Issue 5, p1072–1082, 28 August 2014]</ref>.