The fermentation of beer and wine was originally caused by naturally occurring yeasts present in the environment. Some wineries still use natural yeast strains, however most modern brewers use highly cultured isolates, e.g. Saccharomyces carlsbergensis, named after the Carlsberg Brewery in Copenhagen. The bubbles in sparkling wines such as Champagne are trapped CO2, the result of yeast fermenting sugars in the grape juice. One yeast cell can ferment approximately its own weight of glucose per hour, giving rise to large volumes of CO2. The same process occurs in bread dough - as the CO2 from fermentation is trapped, the dough rises