Trehalose and Abiotic Stress in Biological Systems

Any non-living factors that affect negatively living organisms are reunited under the general term “abiotic stress” and its effects can be and are mitigated by a variety of defense mechanisms developed by the different biological systems in existence. Examples of abiotic stress are desiccation, salinity, high and low temperature. There are two general mechanisms used to counteract abiotic stress: avoidance and adaptation. In the case of avoidance, organisms migrate to deeper soil layers where temperatures are within tolerable range (Roelofs et al., 2008). Adaptation to stress is based on activation of stress defense gene pathways, which results in the production of heat shock proteins, LEA proteins, redox regulating proteins, different compatible solutes, cytochrome P450s (Roelofs et al., 2008). Trehalose, also known as tremalose or mycose, a non-reducing disaccharide, is widely spread in biological systems: bacteria, yeast, fungi, lower and higher plants, as well as insects and invertebrates (Elbein, 2003), and its function is associated with tolerance against multiple abiotic stresses. It was discovered in 1832 by H.A. Wiggers in the ergot of rye and later isolated from mooshrooms by Mitscherlich in 1858, who called it mycose (Richards et al., 2002). In the same year Berthelot isolated a novel sugar from trehala-manna, a secretion left by different insects on leaves on Middle East. He named this new sugar ‘‘trehalique glucose’’ or trehalose (Richards et al., 2002). Initially trehalose was considered to be a rare sugar because it could only be extracted from trehala manna or the resurrection plant. Later Koch and Koch in 1925 discovered it in yeast and established basic protocols for trehalose isolation from yeast (Richards et al., 2002). Still, the cost of trehalose production was high enough so that it limited its use for commercial exploitation. In 1990’s Hayashibara company in Japan discovered a method to mass-produce trehalose inexpensively from starch. The enzymes used in the process, maltooligosyl–trehalose synthase (MTSase) and maltooligosyl–trehalose trehalohydrolase (MTHase), are derived from a non-pathogenic soil bacteria, Arthrobacter sp. (Maruta et al., 1995). Trehalose has multiple functions, and some of them are species specific. In microorganisms trehalose appears to act as an energy source, during certain stages of development such as spore germination (Elbein, 2003). In anhydrobiotic organisms, trehalose is known to accumulate to high concentrations to survive complete dehydration (Drennan et al., 1993), by preserving the membranes during drought period (Crowe et al., 1984). Trehalose acts as a structural component in mycobacteria, being incorporated into glycolipids (Elbein, 1974). In Escherichia coli, trehalose protects against cold stress, presumably by stabilizing cell