The disaccharide trehalose is widely distributed in nature and can be found
in many organisms, including bacteria, fungi, plants, invertebrates and ma
mmals. Due to its particular physical features, trehalose is able to protec
t the integrity of the cell against a variety of environmental injuries and
nutritional limitations. In addition, data available on several species of
bacteria and yeast suggest specific functions for trehalose in these organ
isms. Bacteria can use exogenous trehalose as the sole source of carbon and
energy as well as synthesize enormous amounts of the disaccharide as compa
tible solute. This ability to accumulate trehalose is the result of an elab
orate genetic system, which is regulated by osmolarity. Some mycobacteria c
ontain sterified trehalose as a structural component of the cell wall, wher
eas yeast cells are largely unable to grow on trehalose as carbon source. I
n these lower eukaryotes, trehalose appears to play a dual function: as a r
eserve compound, mainly stored in vegetative resting cells and reproductive
structures, and as a stress metabolite. Recent findings also point to impo
rtant biotechnological applications for trehalose.