ORGANIC SOLUTES IN HYPERTHERMOPHILIC ARCHAEA

We examined the accumulation of organic solutes under optimum growth c onditions in 12 species of thermophilic and hyperthermophilic Archaea belonging to the Crenarchaeota and Euryarchaeota. Pyrobaculum aerophil um, Thermoproteus tenax, Thermoplasma acidophilum, and members of the order Sulfolobales accumulated trehalose. Pyrococcus furiosus accumula ted di-myo-inositol 1,1' (3,3')-phosphate and beta-mannosylglycerate, Methanothermus fervidus accumulated cyclic-2,3-bisphosphoglycerate and beta-mannosylglycerate, while the only solute detected in Pyrodictium occultum was di-myo-inositol 1,1' (3,3') phosphate. Methanopyrus kand leri accumulated large concentrations of cyclic-2,3-bisphosphoglycerat e. On the other hand, Archaeoglobus fulgidus accumulated three phospho rylated solutes; prominent among them was a compound identified as di- glycerol-phosphate. This solute increased in concentration as the sali nity of the medium and the growth temperature were raised, suggesting that this compound sen es as a general stress solute. Di-myo-inositol- 1,1'(3,3')-phosphate accumulated at supraoptimal temperature only. The relationship between the accumulation of unusual solutes and high tem peratures is also discussed.