Enzymes from extremely thermophilic bacteria and archaea: current status and future prospects

Extremely thermophilic bacteria and archaea (Topt≥70°C) inhabit thermal biotopes that are distributed globally in both terrestrial and marine settings. As a group, these microorganisms utilize a very wide array of substrates to support their growth, ranging from lignocellulose to CO2. The enzymes produced by these microorganisms to process their energy and carbon sources are not only intrinsically thermostable and thermoactive, but they have novel characteristics that go beyond their unusually high functional temperature range. There are many potential applications of these enzymes as biocatalysts for biotechnology that go beyond the use of thermophilic DNA polymerases for the polymerase chain reaction. Here, we will consider the basic features of enzymes from extreme thermophiles with an eye toward their broader use as industrial biocatalysts as well as components in metabolic engineering pathways. Genome sequencing and availability of molecular genetic tools have impacted extreme thermophile biotechnology and will play important roles in future efforts to deploy and utilize the biocatalytic potential of these interesting enzymes.