NEW COMPATIBLE SOLUTES RELATED TO DI-MYO-INOSITOL-PHOSPHATE IN MEMBERS OF THE ORDER THERMOTOGALES

The accumulation of intracellular organic solutes was examined in six species of the order Thermotogales by nuclear magnetic resonance spect roscopy, The newly discovered compounds beta-mannosyl-di-myo-inositol- 1,1'(3,3')-phosphate and di-myo-inositol-1,3'-phosphate were identifie d in Thermotoga maritima and Thermotoga neapolitana, In the latter spe cies, at the optimum temperature and salinity the organic solute pool was composed of di-myo-inositol-1,1'(3,3')-phosphate, beta-glutamate, and alpha-glutamate in addition to di-myo-inositol-1,3'-phosphate and eta-mannosyl-di-myo-inositol-1,1'(3,3')-phosphate. The concentrations of the last two solutes increased dramatically at supraoptimal growth temperatures, whereas beta-glutamate increased mainly in response to a salinity stress, Nevertheless, di-myo-inositol-1,1'(3,3')-phosphate w as the major compatible solute at salinities above the optimum for gro wth, The amino acids alpha-glutamate and proline were identified under optimum growth conditions in Thermosipho africanus, and beta-mannosyl glycerate, trehalose, and glycine betaine were detected in Petrotoga m iotherma. Organic solutes were not detected, under optimum growth cond itions, in Thermotoga thermarum and Fervidobacterium islandicum, which have a low salt requirement or none.