The intracellular accumulation of low molecular mass organic compounds in response to stressful conditions was investigated in the thermophilic bacterium Petrotoga miotherma, a member of the order Thermotogales. This led to the discovery of a new solute, whose structure was established as a-d-mannopyranosyl-(1fi2)-a-d-glucopyranosyl-(1 fi2)-glycerate (MGG) by MMR spectroscopy and MS.