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''Brettanomyces'' is able to ferment a wide range of sugars. All strains may possess both alpha can ferment glucose, and beta glucosidases. These enzymes allow ''Brettanomyces'' many strains to break down longer chain carbohydrate molecules (including maltose, can ferment sucrose, starchfructose, and cellulose) and to liberate glycosidically bound sugars which are unfermentable to ''Saccharomyces'' yeasts <ref>[http://www.scribd.com/doc/277758178/Insight-into-the-Dekkera-anomala-YV396-genome Insight into the Dekkera anomala YV396 genomemaltose, although at a slower rate than glucose. Samuel Aeschlimann. Self published on Eureka Brewing Blog. Spet 2015.]</ref>. Extracellular and intracellular alpha-glucosidase activity has been shown to break down sugars up to 9 carbons in one strain of ''B. lambicus'', which is partly responsible for the over-attenuation of wort that some Some strains of ''Brettanomyces'' an achieve can also ferment galactose <ref name="yakobson_introductionSteensels"></ref>.

''Brettanomyces'' strains may possess both alpha and beta glucosidases. These enzymes allow ''Brettanomyces'' strains to break down a broad range of sugars, including longer chain carbohydrate molecules (starch, dextrins, and cellulose/cellobiose), and to liberate glycosidically bound sugars which are unfermentable to ''Saccharomyces'' yeasts. <ref name="Steensels"></ref><ref>[http://www.scribd.com/doc/277758178/Insight-into-the-Dekkera-anomala-YV396-genome Insight into the Dekkera anomala YV396 genome. Samuel Aeschlimann. Self published on Eureka Brewing Blog. Spet 2015.]</ref>.  Extracellular and intracellular alpha-glucosidase activity has been shown to break down sugars up to 9 carbons in one strain of ''B. lambicus'', which is partly responsible for the over-attenuation of wort that some strains of ''Brettanomyces'' an achieve <ref name="yakobson_introduction"></ref>. Alpha glucosidases are the enzymes that allow them to break down maltose and trehalose, as well as dextrins (examples of these dextrins are maltotetraose and maltopentaose). These dextrins are left over after a normal ''Saccharomyces'' fermentation <ref name="Steensels"></ref>.  Glycosides are sugar molecules (including cellobiose <ref>[http://chemwiki.ucdavis.edu/Core/Organic_Chemistry/Carbohydrates/Disaccharides "Disaccharides." UC Davis Chemwiki. Retrieved 05/15/2016.]</ref>) connected to other organic compounds such as acids, alcohols, and aldehydes which are flavor and aroma inactive due to the sugar molecule attached. By cleaving off the sugar molecule through beta-glucosidase activity, ''Brettanomyces'' species can liberate these compounds (called aglycones) into their aroma-active and flavor-active states, or states that may become flavor and aroma active through further modification<ref>Daenen et al., 2008. Evaluation of the glycoside hydrolase activity of a Brettanomyces strain on glycosides from sour cherry (Prunus cerasus L.) used in the production of special fruit beers. FEMS Yeast Res. 8, 1103-1114.</ref>. Therefore ''Brettanomyces'' strains are able to produce novel flavors and aromas from hops, fruits, and fruit pits that ''Saccharomyces'' yeasts cannot produce. In addition, the liberated aroma and flavor active compounds may be further processed by ''Brettanomyces'' through ester production or destruction pathways. See [[Brettanomyces#Glycosides_and_Beta-Glucosidase_Activity|Beta-Glucosidase Activity]] for more information.

Beta-glycosidase enzymes can be added artificially, however there has been much interest in the natural capability of microorganisms to produce beta-glycosidases<ref name="Winterhalter"></ref>. Microorganisms that can break down glycosides by using beta-glucosidases can then access the resulting sugars for fermentation (for example, cellulose and cellobiose) <ref name="Steensels"></ref>. There are two major categories of glucosidase activity: endogenous and exogenous. Endogenous enzymatic activity takes place inside of the cell, and exogenous enzymatic activity takes place outside of the cell. Bacteria and fungi that show endogenous glucosidase activity have been shown not to be effective in alcoholic fermentation due to not tolerating low pH (optimum pH of 5), glucose, and/or ethanol. Generally, the flavorless glycosides remain unaffected by yeast fermentation, leaving them unused as a potential source for flavor and aroma <ref name="Winterhalter"></ref>.

Exogenous beta-glycosidase activity has been shown to be much more effective at releasing aglycones from glycosides in bacteria and fungi. For glycosides which contain a glucose, which is the majority, beta-glucosidase cleaves the sugar, thus releasing the aglycone. For glycosides that contain disaccharides, usually another enzyme must be present to first break down the disaccharide before the beta-glucosidase can release the aglycone (beta-xylosidase, alpha-arabinosidase, alpha-rhamnosidase, or beta-apiosidase) <ref name="Winterhalter"></ref>. However, glycosides in tea leaves that contain disaccharide sugars (cellulose/cellobiose) have been observed to be broken down without the use of these other enzymes; the beta-glucosidase cleaves the aglycone from the disaccharide on its own. Some species of yeast (''Debaryomyces castelli'', ''D. hansenii'', ''D. polymorphus'', ''Kloeckera apiculata'', ''Hansenula anomala'', and ''Brettanomyces'' spp), bacteria (''Oenococcus oeni''), and fungi (''Aspergillus niger'') have been found to have strain dependent beta-glucosidase activity, however several inhibitors for glucosidase activity vary for different strains of microbes. These inhibitors include the presence of glucose, pH, temperature, ethanol, and phenols <ref name="Maicas"></ref><ref name="Mansfield">[https://theses.lib.vt.edu/theses/available/etd-07262001-172630/unrestricted/Mansfieldthesis.pdf Quantification of Glycosidase Activities in Selected Strains of Brettanomyces bruxellensis and Oenococcus oeni. A. K. Mansfield, B. W. Zoecklein and R. S. Whiton. 2001.]</ref>. For example, for some strains of ''O. oeni'', as little as 10mg/L of glucose is enough to inhibit beta-glucosidase activity, or the presence of alcohol or typical wine pH (3.0 - 4.0) was enough to inhibit. Other strains of ''O. oeni'' are not inhibited by some or all of these inhibitors <ref>[http://www.sciencedirect.com/science/article/pii/S0168160505003296 A survey of glycosidase activities of commercial wine strains of Oenococcus oeni. Antonio Grimaldi, Eveline Bartowsky, Vladimir Jiranek. 2005.]</ref>.