Extreme Thermophiles

Abstract

Abstract Extreme thermophiles are microorganisms adapted to temperatures normally found only in hot springs, hydrothermal vents and similar sites of geothermal activity. These unicellular organisms include diverse archaea and bacteria, and they span a wide range of metabolic strategies. Various molecular features enable the cells of extreme thermophiles to function optimally at temperatures that kill other cells. These features include low‐molecular weight compounds that stabilise the conformations of proteins and nucleic acids, enzymes with intrinsically stable folding of the polypeptide and unusual lipids that form highly impermeable membranes. The intrinsically stable enzymes of extreme thermophiles offer advantages for industrial and diagnostic processes ranging from ore processing to molecular genotyping. Key Concepts: Bacteria and archaea consist of very simple (prokaryotic) cells but vary greatly with respect to metabolic capabilities, physiological limits and other fundamental properties. Diverse bacteria and archaea require the temperatures found in geothermal environments for optimal growth, and are classified as extreme thermophiles. Geothermal activity typically provides chemical energy and nutrients that microorganisms can utilise. Extreme thermophiles use two basic strategies to avoid thermal denaturation of their enzymes: extrinsic stabilisation, conferred by certain small molecules, and intrinsic stabilisation, conferred by the specific structure and conformation of the enzyme itself. Intrinsically thermostable enzymes of extreme thermophiles allow certain chemical reactions to be catalysed with high specificity at high temperatures or under other harsh conditions.