Instant dry yeast is used for manufacturing steamed bun, steamed roll, bread, pastry, cookies, fried dough twist, twisted cruller and other fermented food. There are many kinds of yeast cloning vectors.It is a single-celled fungus and a natural leavening agent.It is a commonly used eukaryotic receptor cell in gene cloning experiments. Yeast is widely distributed in nature, mainly growing in acidic moist environment containing sugar.