Many microorganisms produce the trehalose synthase. The trehalose synthase and the producer bacteria are overviewed in order to research them in the next step. Trehalose is composed of two glucose molecules and it is a disaccharide, bound the two units by alpha-1ÿ1 linkage. The trehalose has many properties and it is known to be one of the sources of energy in bacteria espically extremophiles. Microorganisms containing trehalose can live in cold or dry environment, so it is used widely in industrial. Trehalose is also used for various applications in the field of pharmacy. The producing of trehalose rely on the chemical synthesis and biosynthesis, the first method is worse than biosynthesis because of the too low productivitying. Then the industries usually use the biosynthesis to produce trehalose. Biosynthesis produces trehalose using enzyme. Now trehalose synthase is used widely to produce trehalose because of its high productivitying and simple process. The main source of the trehalose synthase is bacteria, but the trehalose also can be found in fungi, insects, invertebrates, and plants.