History

• 5,000 years ago, ancient Egyptians used yeast and fermentation to produce alcohol and leaven bread
• Early mixtures contained wild yeasts and lactic acid bacteria as natural contaminants in cultivated grains and fruits
• Over time, cultures were started to help select superior yeasts, by saving a good batch of wine or dough to inoculate the next batch

Louis Pasteur

Science

• In the late 1860s, Louis Pasteur identified yeast as a living, microscopic, single celled organism, responsible for alcoholic fermentation and bread leavening
• As soon as yeast could be isolated in a pure culture form, scientists began identifying each strain and its capability
• Alternative uses were discovered for live yeast in other areas of nutrition, such as agriculture

Technology

• Certain yeasts are more suited to live in the rumen than others, due to the rumen conditions, substrate types and competition from other microorganisms
• By DNA fingerprinting, it is possible to identify each strain and compare the variation in the rumen
• The genetics of the various strains are highly variable, even though they are all
  in the same species group