Abstract：

 Deinococcus radiodurans is a microorganism that can adjust, survive or thrive in hostileconditions and has been described as “the strongest microorganism in the world”. The underlyingmechanism behind the exceptional resistance of this robust bacterium still remains unclear. Osmoticstress, caused by abiotic stresses such as desiccation, salt stress, high temperatures and freezing, isone of the main stresses suffered by microorganisms, and it is also the basic response pathway bywhich organisms cope with environmental stress. In this study, a unique trehalose synthesis-relatedgene, dogH (Deinococcus radiodurans orphan glycosyl hydrolase-like family 10), which encodes anovel glycoside hydrolase, was excavated using a multi-omics combination method. The contentaccumulation of trehalose and its precursors under hypertonic conditions was quantified by HPLCMS. Ours results showed that the dogH gene was strongly induced by sorbitol and desiccationstress in D. radiodurans. DogH glycoside hydrolase hydrolyzes _-1,4-glycosidic bonds by releasingmaltose from starch in the regulation of soluble sugars, thereby increasing the concentration of TreS(trehalose synthase) pathway precursors and trehalose biomass. The maltose and alginate content inD. radiodurans amounted to 48 μg mg protein−1 and 45 μg mg protein−1, respectively, which were9 and 28 times higher than those in E. coli, respectively. The accumulation of greater intracellularconcentrations of osmoprotectants may be the true reason for the higher osmotic stress tolerance ofD. radiodurans.

KeyWords:

Deinococcus radiodurans; osmotic stress; trehalose; novel glycoside hydrolase; DogH