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===Carbohydrate Metabolism===
''Brettanomyces'' is able to ferment a wide range of sugars. All strains can ferment glucose, and many strains can ferment sucrose, fructose, and maltose, although at a slower rate than glucose. Some strains can also ferment galactose, mannose, ethanol, acetic acid, and glycerol, although there are some contradicting studies in science regarding the specifics, and many previously published studies do not specify whether testing conditions were aerobic or anaerobic even though the available availability of oxygen effects whether or not certain sugars can be fermented by a given strain of ''Brettanomyces'' <ref name="Steensels"></ref><ref name="smith_divol_2016"></ref>. Acetic acid, glycerol, succinic acid, and ethanol are only consumed if oxygen is present <ref name="smith_divol_2016"></ref>. The addition of small amounts of O2 stimulates glucose fermentation, as well as H+ acceptors such as acetaldehyde, acetone, pyruvic acid and other carbonyl compounds <ref name="yakobson_introduction">[http://www.brettanomycesproject.com/dissertation/introduction/ Yakobson, Chad. The Brettanomyces Project. Introduction. Retrieved 8/11/2015.]</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 long chain carbohydrate molecules (polysaccharides, 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 9-12 chain carbons in one strain of ''B. lambicus'' (now classified as ''B. bruxellensis''), which is partly responsible for the slow, over-attenuation of wort that some strains of ''Brettanomyces'' an achieve in beers such as lambic and American sour beers <ref name="yakobson_introduction"></ref><ref name="smith_divol_2016"></ref>. Alpha-glucosidases are the enzymes that allow them to break down maltose, turanose, melezitose, and trehalose, as well as dextrins such as maltotetraose and maltopentaose. These enzymes work by cleaving off glucose that can be directly consumed by the cell, leaving a shorter chain sugar behind which is then further broken down. In the case of extracellular alpha-glucosidase activity, this breakdown of complex sugars occurs outside of the cell and may benefit other microorganisms if present such as lactic acid bacteria. These dextrins are left over after a normal ''Saccharomyces'' fermentation <ref name="Steensels"></ref>. Some other polysaccharides can be fermented by ''Brettanomyces'', including starch, laminarin, and pectin <ref name="Crauwels1"></ref>. The more complex the starch or sugar, the slower it is hydrolyzed by the alpha-glucosidase enzymes. The optimal pH for the alpha-glucosidase enzyme produced by one strain of ''B. bruxellensis'' was 6 and at a temperature of 39-40°C (102-104°F), and its activity was greatly reduced below a pH of 4.5 and above 8 (although citric acid was used as a buffer, and its effects on the enzyme was not compared to other acids), which might contribute to slower ''Brettanomyces'' fermentation in acidic beers <ref name="Kumara_1993">[http://aem.asm.org/content/59/8/2352.short Localization and Characterization of α-Glucosidase Activity in Brettanomyces lambicus. H. M. C. Shantha Kumara, S. De Cort and H. Verachtert. 1993.]</ref>.
The ability of a given ''Brettanomyces'' strain to ferment different types of sugars might be at least partially linked to its source of isolation. For example, a strain of ''B. bruxellensis'' isolated from a soft drink could not ferment the disaccharides maltose, turanose, or the trisaccharide melezitose, whereas all of the other ''B. bruxellensis'' strains isolated from beer and wine could ferment these disaccharides/trisaccharide. The beer strains, however, were unable to ferment cellobiose or gentiobiose, as well as arbutin and methyl-glucoside. The wine strains were able to ferment these disaccharides, perhaps because they were adapted to the environment in which they were isolated from (wine barrels). Further studies are needed to see if this is a trend throughout the species <ref name="Crauwels1"></ref>.
Currently, research into how well ''Brettanomyces'' strains ferment the trisaccharide maltotriose has not been explored much by science, however , one study found that ''B. custersianus'' can ferment maltotriose. Another study found that all 7 strains of ''B. bruxellensis'' tested could ferment maltotriose, but not the trisaccharide raffinose. More investigation into this possibility is needed <ref>[http://www.asbcnet.org/events/archives/2015Meeting/proceedings/Pages/54.aspx Determination of sugar metabolism profiles of non-traditional yeasts in the Saccharomyces and Brettanomyces families. J. D. Cook, W. A. DEUTSCHMAN. ASBC Proceeding. 2015.]</ref><ref name="Crauwels1"></ref>.
Just like in other yeast species, the temperature has a direct effect on the rate of fermentation for ''Brettanomyces''. The optimal fermentation rate temperature range for ''Brettanomyces'' is between 25-32°C (77-90°F). Fermentation rate is about half as slow at 20°C (68°F). ''Brettanomyces'' will still grow at temperatures as low as (and maybe lower than) 15°C (59°F) and will be much slower, however one study showed a slightly higher viability during the full -time period of fermentation at 15°C as opposed to the optimal growth and fermentation temperature range of 20-32°C. At a temperature of 35°C (95°F), fermentation is greatly inhibited due to cell death. The primary byproducts of ''Brettanomyces'' fermentation, which are ethanol, acetic acid, and CO2, are produced both during growth but also during fermentation after growth has stopped. At the more optimal fermentation temperatures of 25-32°C, ethanol and acetic acid are produced faster from fermentation, but the amounts of ethanol and acetic acid produced from fermentation are not affected by temperature (i.e. higher temperatures do not produce more ethanol and acetic acid from the same amount of sugar, they are just produced faster at warmer temperatures because fermentation is faster) <ref name="Brandam_2008" />. The warmer temperature ranges that are ideal for ''Brettanomyces'' fermentation rates and growth rates may still produce unfavorable flavors such as higher alcohols, however , this has not been analyzed as far as we know <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1555689637792578/ MTF conversation with Richard Preiss of Escarpment Labs. 01/20/2017.]</ref>.
The below table is an example of the variety of sugar types that different strains/species of ''Brettanomyces'' banked at the [https://catalogue.ncyc.co.uk National Collection of Yeast Cultures] can ferment under semi-aerobic fermentation and aerobic growth (the '''semi-aerobic''' fermentation value is probably more useful for brewers since oxygen availability is limited during fermentation in normal brewing practices):
====Glycosides and Beta-Glucosidase Activity====
Glycosides are flavorless compounds often found in plants/fruits that are composed of a molecule (often a flavor active compound) bound to a sugar molecule. The glycosidic bond can be broken, releasing the sugar molecule and the potentially flavor active compound. These bonds can be broken with exposure to acid, as well as specific enzymes (beta-glucosidase) which can be added synthetically or produced naturally by some microorganisms, including some strains of ''Brettanomyces'' that have beta-glucosidase enzyme activity (mostly ''B. anomalus'' strains) <ref>[https://en.wikipedia.org/wiki/Glycoside "Glycoside." Wikipedia. Retrieved 06/27/2016.]</ref>. The release of flavor molecules from glycosides is thought to contribute to the flavor development of aging wines, as well as kriek (cherry) lambic <ref name="Daenen2">[http://onlinelibrary.wiley.com/doi/10.1111/j.1567-1364.2008.00421.x/pdf 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. Luk Daenen, Femke Sterckx, Freddy R. Delvaux, Hubert Verachtert & Guy Derdelinckx. 2007.]</ref>. It is speculated that flavor compounds from hops can also be released from glycosides <ref name="Daenen1">[http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2672.2007.03566.x/full Screening and evaluation of the glucoside hydrolase activity in Saccharomyces and Brettanomyces brewing yeasts. L. Daenen, D. Saison, F. Sterckx, F.R. Delvaux, H. Verachtert, G. Derdelinckx. 2007.]</ref>, however , at least one study has shown no significant difference in a blind taste test between hopped beer exposed to beta-glucosidase enzyme and hopped beer that was not exposed to the enzyme <ref name="Vervoort">[http://onlinelibrary.wiley.com/wol1/doi/10.1111/jam.13200/abstract Characterization of the recombinant Brettanomyces anomalus β-glucosidase and its potential for bioflavoring. Yannick Vervoort, Beatriz Herrera-Malaver, Stijn Mertens, Victor Guadalupe Medina, Jorge Duitama, Lotte Michiels, Guy Derdelinckx, Karin Voordeckers, and Kevin J. Verstrepen. 2016.]</ref>.
See the [[Glycosides]] page for more details.