Which type of yeast is used to ferment lagers?

Bottom fermenting yeast, also known as Saccharomyces pastorianus or Saccharomyces carlsbergensis, is the type of yeast used to ferment lagers. This yeast operates at cooler fermentation temperatures, typically between 45°F and 55°F (7°C to 13°C), which allows for a slower fermentation process compared to the warmer temperatures favored by top fermenting yeast used in ales. The fermentation process with bottom fermenting yeast leads to beers that are generally cleaner and crisper in flavor, with fewer fruity esters and phenols, which is characteristic of lager styles. This distinct fermentation method develops the smooth character associated with lagers, making it essential for producing this type of beer.