Thermoadaptation of methanogenic bacteria by intracellular ion concentration

Abstract

An inter- and intra-species correlation was found between the intracellular potassium concentration and growth temperature within the Methanobacteriales, comprising mesophiles as well as moderate (Methanobacterium thermoautotrophicum) and extreme thermophiles (Methanothermus fervidus, Mt. sociabilis). Potassium concentrations in different species were determined at optimal growth temperatures and for the same species cultured at different temperatures. The main anionic component was found to be the unusual trianionic cyclic 2,3-diphosphiglycerate. In vitro experiments with the thermolabile enzymes glyceraldehyde-3-phosphate dehydrogenase and malate dehydrogenase from Mt. fervidus indicated that the potassium salt of the cyclic diphosphoglycerate acts as potent thermostabilizer. Thus it appears that, for the methanogens, changes in the intracellular ion concentration are the basis of thermoadaptation. © 1988.