In the germination of many seeds the starches contained therein are converted by enzymes into soluble starch or sugars, and thus nourish the young plant. Many bacteria are capable of breaking down starches, as well as proteids, and some moulds develop amylolytic, as well as proteolytic, enzymes of marked activity.

Of late years much use has been made of a number of these enzymes. That from grain - barley, malt - containing the enzyme diastase has been widely used, especially in proprietary medicines.