The dominant types of yeast used to make beer are "Saccharomyces cerevisiae", known as ale yeast, and "Saccharomyces pastorianus", known as lager yeast; "Brettanomyces" ferments lambics, and "Torulaspora delbrueckii" ferments Bavarian weissbier. Before the role of yeast in fermentation was understood, fermentation involved wild or airborne yeasts, and a few styles such as lambics still use this method today. Emil Christian Hansen, a Danish biochemist employed by the Carlsberg Laboratory, developed pure yeast cultures which were introduced into the Carlsberg brewery in 1883, and pure yeast strains are now the main fermenting source used worldwide.