EFFECTS OF TEMPERATURE, SALINITY, AND MEDIUM COMPOSITION ON COMPATIBLE SOLUTE ACCUMULATION BY THERMOCOCCUS SPP

The effects of salinity and growth temperature on the accumulation of intracellular organic solutes were examined by nuclear magnetic resona nce spectroscopy (NMR) in Thermococcus litoralis, Thermococcus celer, Thermococcus stetteri, and Thermococcus zilligii (strain AN1). In addi tion, the effects of growth stage and composition of the medium were s tudied in T. litoralis. A novel compound identified as beta-galactopyr anosyl-5-hydroxylysine was detected in T. litoralis grown On peptone-c ontaining medium. Besides this newly discovered compound, T. litoralis accumulated mannosylglycerate, aspartate, alpha-glutamate, di-myo-ino sitol-1,1' (3,3')-phosphate, hydroxyproline, and trehalose. The hydrox yproline and beta-galactopyranosyl-5-hydroxylysine were probably deriv ed from peptone, while the trehalose was derived from yeast extract; n one of these three compounds was detected in the other Thermococcus st rains examined. Di myo-inositol-1,1'(3,3')-phosphate, aspartate, and m annosylglycerate were detected in T. celer and T. stetteri, and the la tter organism also accumulated alpha-glutamate. The only nonmarine spe cies studied, T. zilligii, accumulated very low levels of alpha-glutam ate and aspartate. The levels of mannosylglycerate and aspartate incre ased in T. litoralis, T. celer, and T. stetteri in response to salt st ress, while di-myo-inositol-1,1' (3,3')-phosphate was the major intrac ellular solute at supraoptimal growth temperatures. The phase of growt h had a strong influence on the types and levels of compatible solutes in T. litoralis; mannosylglycerate and aspartate were the major solut es during exponential growth, while di-myo-inositol-1,1'(3,3')-phospha te was the predominant organic solute during the stationary phase of g rowth. This work revealed an unexpected ability of T. litoralis to sca venge suitable components from the medium and to use them as compatibl e solutes.