The ability of archaea to survive in extreme environments is primarily due to:
Ability of archaea to colonize boiling hot springs, saturated salt lakes, acidic solfataras, and pressurized deep-sea vents correlates strongly with membrane and envelope adaptations that maintain integrity where bacterial bilayers would disintegrate. Ether linkages between glycerol-1-phosphate and branched isoprenoid chains resist acid hydrolysis and oxidative cleavage that would disrupt ester bonds at high temperature. Tetraether monolayers spanning entire membrane reduce proton permeability by an order of magnitude, preserving chemiosmotic potential even at pH below 2. Cyclopentane rings formed in bipolar lipids tighten packing, increasing thermal stability, while extensive glycosylation of S-layer proteins shields against proteases. Intracellular adaptations include thermostable enzymes with increased ionic interactions, reverse gyrase introducing positive supercoiling to prevent DNA melting, and accumulation of compatible solutes like di-myo-inositol phosphate. Mutation rate alone does not explain survival; presence of nuclear membrane is not found in prokaryotes. Thus unique cell membrane composition, coupled with compatible wall polymers, remains primary determinant of extremophily, enabling archaea to exploit niches inaccessible to most life.
Ref: Albers & Meyer, Nature Rev Microbiol 2011, Extremophile Adaptations; Rothschild & Mancinelli, Nature 2001, Life in Extreme Environments.